JP2002332824A - Regeneration control method for diesel particulate filter device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a regeneration control method of diesel particulate filters, capable of accurately detecting clogging state of the filters, in a simple control method. SOLUTION: A diesel particulate filter device 10A conducts determination of the start of regeneration treatment of the filters 6A and 6B for collecting particulate materials in an exhaust gas G, using exhaust pressures PI and PO on the upstream and downstream side; and in determining the clogged state of the filters 6A and 6B, a regeneration control device determines an operation region of an engine 1 and performs clogging determination using different types of clogging determining means, depending on the operation region.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a regeneration control method for a diesel particulate filter (DPF) that collects particulate matter (PM) in an internal combustion engine such as a diesel engine mounted on a vehicle.

[0002]

2. Description of the Related Art Exhaust gas discharged from a diesel engine mounted on a vehicle or the like contains particulate matter called particulate matter (PM), and a diesel particulate filter (DPF) is used to remove the particulate matter. Equipped devices have been attempted.

In this diesel particulate filter device, as shown in FIG. 1, filters 6A and 6B are formed by sandwiching a non-woven fabric made of ceramic fiber such as SiC between heat-resisting metal meshes on the exhaust gas downstream side of a diesel engine 1.
A plurality of types are attached, and the exhaust gas G is passed alternately, and the collection of the particulate matter and the regeneration of the filter are alternately repeated while being alternately collected to collect the particulate matter discharged from the engine 1. A single filter 6C and a bypass passage 12 that bypasses the filter 6C are provided on the exhaust downstream side of the diesel engine 1 as shown in FIG.
Is heated by a heater 7C to perform regeneration.

As shown in FIG. 3, even in a type in which one filter 6D is provided downstream of the exhaust of the diesel engine 1, an oxidation catalyst 9 may be provided upstream of the filter 6D without providing a bypass passage. Alternatively, a continuous regeneration type diesel that performs a regeneration process of the filter 6D by changing the temperature or composition of the exhaust gas G by carrying out regeneration control that changes the operating state of the engine 1 by carrying a catalyst on the filter 6D or the like. There is also a particulate filter device 10C.

[0005] In these filters, as the accumulation of the collected particulate matter progresses, clogging of the filter progresses and the exhaust pressure before and after the filter changes. Is determined using

Therefore, as shown in FIG. 1, in a diesel particulate filter device 10A having a plurality of filters 6A and 6B, the filters 6A and 6B are used.
On the upstream side of B, an inlet side pressure sensor (pre-pressure sensor) 51
However, on the downstream side, an outlet pressure sensor (back pressure sensor)
Numerals 52 are provided to detect the inlet-side exhaust pressure PI and the outlet-side exhaust pressure PO.

Further, as shown in FIGS. 2 and 3, a diesel particulate filter device 10B (10) of a type that repeats collection and regeneration with a single filter 6C (6D).
In C), an inlet-side pressure sensor 51 is disposed upstream of the filter 6C (6D), and an outlet-side pressure sensor 52 is disposed downstream of the filter 6C (6D). The inlet-side exhaust pressure PI and the outlet-side exhaust pressure PO Has been detected.

When the exhaust pressure PI on the inlet side of each of the filters 6A to 6D and the pressure ratio before and after (Rp = PI / PO) become larger than predetermined clogging state determination values PI0 and Rp0, the concentration of particulate matter is reduced. Filter 6A (or 6B),
6C and 6D determine that the filter is clogged, switch the path of the exhaust gas G, and change the other filter 6B (or 6C).
In A), the particulate matter is collected, the exhaust gas is released to the bypass passage, and the filters 6A (or 6B), 6C, and 6D that are determined to be in the clogged state are regenerated.

The regeneration process is performed by the diesel particulate filter devices 10A and 10B shown in FIGS.
The heaters 7A (or 7B) and 7C are energized and heated, and the collected particulate matter is incinerated.
B) and 6C are regenerated, and in the continuous regenerating type diesel particulate filter device 10C shown in FIG.
The exhaust gas G having a temperature and a component composition suitable for the regeneration of the filter 6D is generated to regenerate the filter 6D.

In any of these diesel particulate filter devices, the upstream exhaust pressure on the upstream side of the filter, or the upstream exhaust pressure on the upstream side and the downstream exhaust pressure on the downstream side, are used to filter the filter. The clogging state is determined to determine whether or not the regeneration process has started, and the collection and regeneration filters are switched by switching the exhaust gas passage, the collection and regeneration are switched, or the engine operating state is changed. Switching between collection and regeneration is performed to regenerate each filter.

[0011]

However, when the exhaust pressure on the upstream side of the filter is used for judging clogging, the exhaust pressure on the inlet side increases as the clogging of the filter increases. Is the engine speed,
In order to be affected by load, exhaust temperature, etc., it is necessary to set an inlet-side exhaust pressure determination value corresponding to the operating state of the engine in advance and store it in the regeneration control device in the form of map data or the like. .

At the time of clogging determination, an inlet-side exhaust pressure determination value corresponding to the operating state of the engine is calculated, and this inlet-side exhaust pressure determination value is compared with the measured inlet-side exhaust pressure. Therefore, there is a problem that complicated control is required in consideration of operating conditions such as the engine speed, load, and exhaust temperature.

Further, when the clogging is determined based on the exhaust pressure on the inlet side, as shown in the upper part of FIG. 6, the accuracy of the clogging determination is good in the high load operation region (solid line: H1). However, in the low load and middle load operation regions (dotted line: L1), there is a problem that the detection delay D1 occurs and the accuracy of the clogging determination is deteriorated.

On the other hand, when the pressure ratio, which is the ratio of the exhaust pressure on the inlet side to the exhaust pressure on the outlet side, is used for judging clogging, the influence of operating conditions such as engine speed and load is reduced, so that control is simplified. However, there is a problem that the accuracy of the pressure ratio is poor and calculation such as averaging of measurement data and noise removal is required, and a detection delay is caused.

In particular, when the clogging state is determined based on this pressure ratio, as shown in the lower diagram of FIG. 6, the clogging is performed in the low load and medium load operation regions (dotted line: L2). Although the accuracy of the determination is good, in the high-load operation region (solid line: H2), there is a problem that the detection delay D2 occurs and the accuracy of the clogging determination is deteriorated.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems of the prior art, and an object thereof is to provide an exhaust pressure on the inlet side or an exhaust pressure on the downstream side of a diesel particulate filter device. In the regeneration control method of the diesel particulate filter device that determines the start of the regeneration of the filter at the exhaust pressure of the diesel particulate filter device, the regeneration control of the diesel particulate filter device capable of accurately detecting the clogged state of the filter by a simple control method. It is to provide a method.

[0017]

SUMMARY OF THE INVENTION A method for controlling the regeneration of a diesel particulate filter device to achieve the above object is constituted as follows.

1) A filter connected to an exhaust passage of an engine for collecting particulate matter in the exhaust gas and a filter for oxidizing the collected particulate matter for regeneration processing are alternately switched. Having a plurality of filters for purifying particulate matter in the filter, a regeneration means for oxidizing and removing particulate matter collected by the filter, and an inlet pressure sensor for detecting an inlet exhaust pressure of the filter. An outlet-side pressure sensor for detecting the outlet-side exhaust pressure of the filter, and regeneration control for controlling the filter regeneration processing operation by inputting the inlet-side exhaust pressure and the outlet-side exhaust pressure, which are detection values of these exhaust pressure sensors. In a diesel particulate filter device provided with a device, the regeneration control device includes a plurality of different types of clogging determination means, When determining the clogging state, the operating area of the engine operating state is determined, the clogging determining means corresponding to the operating area is selected, and clogging is determined by the selected clogging determining means. Be composed.

The regenerating means includes an electric heater or the like for heating each filter during the regenerating process. In this case, the regenerating process includes switching of the filter, energizing the heater of the regenerating filter, and removing fine particles. There is an oxygen supply and the like for combustion of solid substances.

2) The exhaust gas is connected to the exhaust passage of the engine, and alternately repeats the collection of particulate matter in the exhaust gas and the regeneration process for oxidizing and removing the collected particulate matter. A filter for purifying the particulate matter, a regeneration unit for oxidizing and removing the particulate matter collected by the filter, an inlet pressure sensor for detecting an exhaust pressure on an inlet side of the filter, and an outlet of the filter. Outlet pressure sensor for detecting the side exhaust pressure, and a regeneration control device for inputting the exhaust gas pressure on the inlet side and the exhaust pressure on the exit side which are the detection values of these exhaust pressure sensors and controlling the regeneration processing operation of the filter. In the diesel particulate filter device, the regeneration control device includes a plurality of different types of clogging determination means, and determines a clogged state of the filter. When, to determine the operating region of the engine operating condition, and selects the clogging determination means corresponding to the operating region, configured to perform the clogging determination by said clogging determination means that the selected.

3) In the regeneration control method for a diesel particulate filter device, the regeneration control device determines a pressure ratio, which is a ratio between the inlet-side exhaust pressure and the outlet-side exhaust pressure, to a predetermined pressure ratio. By comparison with the value,
A first clogging determining means for determining a clogged state of the filter, and a second determining means for determining a clogged state of the filter by comparing the inlet side exhaust pressure with a predetermined inlet side exhaust pressure determination value. When the clogging state of the filter is determined, an operation area of the engine is determined, and when it is determined that the operation area of the engine is in the low load operation area and the medium load operation area, The first clogging determination means performs clogging determination, and if it is determined that the engine operating area is in the high load operation area, the second clogging determination means performs clogging determination. It is composed of

According to these configurations, when the regeneration control device determines the clogged state of the filter, it determines the operating region of the engine, and performs clogging determination by different types of determination methods depending on the operating region. In addition, clogging can be determined by a determination method most suitable for the operation region, and the accuracy of clogging determination can be improved.

In addition, each clogging determination method is not good,
In an operation region where complicated control is required, clogging determination is not performed and other clogging determination methods are used, so that control can be simplified and response delay can be avoided.

According to this configuration, as shown in FIG. 6, during low load and medium load operation, the filter clogging progresses during L1 and L2 because both the temperature and the flow rate of the exhaust gas are low. Also, the inlet-side exhaust pressure PI does not immediately reach the inlet exhaust-pressure limit value (inlet-side exhaust pressure determination value) PI0, and a detection delay D1 occurs. On the other hand, the pressure ratio Rp increases with the clogging of the filter. Since the pressure gradually increases and reaches the pressure ratio limit value (clogging state determination value) Rp0, the clogging state can be accurately determined based on the pressure ratio Rp.

In the high load operation H1 and H2, the detection delay D2 occurs at the pressure ratio Rp even if the filter clogging progresses, but the inlet side exhaust pressure PI is higher than the pressure ratio Rp. Since the pressure reaches the inlet exhaust pressure limit value PI0, the clogging state can be accurately determined based on the inlet-side exhaust pressure PI.

By combining a plurality of clogging determination methods in this manner, the mutual disadvantages of the respective determination methods can be compensated for, and the entire engine operating region can be covered while maintaining good clogging determination accuracy. It becomes possible.

[0027]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring to the drawings, a regeneration control method for a diesel particulate filter device (DPF device) according to an embodiment of the present invention will be described. A description will be given of a diesel particulate filter device of a type that alternately switches between a filter and a filter for regeneration processing.

FIGS. 1 to 3 show the configuration of a diesel particulate filter device according to the present invention, and FIG. 4 shows a control flow of a regeneration control method for the diesel particulate filter device according to the present invention. is there.

The diesel particulate filter device 10A shown in FIG. 1 has two filters 6A and 6B which are formed by sandwiching a non-woven fabric made of ceramic fiber such as SiC between two wire meshes. The passage of the exhaust gas G flowing from the exhaust passage 2 is changed from one filter 6A (or 6B) to the other filter 6B (or 6B).
A) A switching valve (passage switching means) 4 for switching to A), and heaters 7A, 7B for heating each of the filters 6A, 6B at the time of the regeneration processing, at least one of the above-mentioned holding wire meshes being configured to be able to conduct electricity. Formed.

An inlet pressure sensor 51 is provided in the exhaust passage 2 on the upstream side of the diesel particulate filter device 10A, and an outlet pressure sensor 52 is provided on the downstream side of each of the filters 6A and 6B.

Furthermore, regeneration control such as switching valve control and filter heating control is performed by inputting an inlet-side exhaust pressure PI detected by the inlet-side pressure sensor 51 and an outlet-side exhaust pressure PO detected by the outlet-side pressure sensor 52. A DPF control unit 80 for performing the control is provided in a controller (control unit: C / U) 8 called an engine control unit (ECU). More specifically, it is input as a control program.

The DPF control unit 80 includes an engine operating area determining unit 81, a first clogging determining unit (first regeneration start determining unit) 82, and a second clogging determining unit (second regeneration start determining unit) 83. Is included.

The engine operating region determining means 81 compares the engine load Q with a predetermined load determination value Q0, and if the engine load Q is smaller than the predetermined load determination value Q0, the engine load Q is determined to be low and medium. It is determined that the engine is in the load operation region, and clogging for starting regeneration is performed by the first clogging determining means 82, and the engine load Q is reduced to a predetermined load determination value Q0.
If it is larger, it is determined that it is in the high load operation region, and the clogging determination for starting regeneration is performed by the second clogging determination unit 83.

In the first clogging determining means 82, the pressure ratio calculated from these exhaust pressures PI and PO (Rp = P
When the I / PO) exceeds a pressure ratio determination value Rp0, which is a predetermined clogging state determination value, the particulate matter (P)
M) It is determined that the concentration filter 6A (or 6B) has become clogged. The pressure ratio is (P
(PO / PI) can be employed instead of (I / PO).

The second clogging judging means 83 detects particulate matter (PM) when the inlet-side exhaust pressure PI exceeds an inlet-side exhaust pressure judgment value PI0 which is a predetermined judgment value of the clogging state. Centralized filter 6A (or 6B)
Is determined to be in a clogged state.

The pressure ratio determination value Rp0 and the inlet-side exhaust pressure determination value PI0 are determined in consideration of the exhaust pressure loss allowable by the engine, the pressure resistance of the filter, and the like. Where P
Since the pressure ratio Rp at the time of collecting M becomes unstable, correction is performed.

In accordance with these determinations, the flow of the exhaust gas G is switched by the switching valve 4, and the other filter 6B (or 6A) is configured to collect particulate matter.

The control of the diesel particulate filter device 10A is performed according to the flow shown in FIGS. This flow is executed in parallel with the control of the engine 1, and is shown as a control flow focusing on one of the plurality of filters 6A and 6B for ease of explanation. In practice, a plurality of filters 6A,
6B are simultaneously controlled, so that the entire filter control is performed collectively, rather than the control for each of the filters 6A and 6B.

First, an outline of the flow of the entire reproduction control will be described with reference to FIG.

In the control flow of FIG. 4, when started, one of the filters 6A (or 6B) to be controlled collects particulate matter in the collection mode of step S10, and the next step In S20, the filter 6A
Is determined to be the start of reproduction, and if it is determined that the reproduction is not started, the process returns to the collection mode of step S10,
The collection is continued by the filter 6A.

If it is determined in step S20 that the regeneration has started, the flow shifts to the regeneration mode in step S30. In the regeneration processing in step S30, the switching valve 4 is controlled to switch the passage of the exhaust gas G. In the filter 6A, preheating of the filter by energizing the heater 7A, introduction of auxiliary air for supplying oxygen for oxidizing the collected particulate matter, cooling of the filter 6A, and the like are performed. During this time, the particulate matter is collected by the other filter 6B (or 6A).

After the regeneration process in step S30 is completed, the process enters the standby state in step 40, and the exhaust gas G passage is switched in accordance with the transition to the regeneration mode of the other filter 6B. Return to

Next, the control for judging the start of reproduction according to the present invention will be described with reference to FIG.

First, as shown in FIG.
First, in step S21, the engine operating area determining means 81 determines whether the operating state of the engine is in the low-load, medium-load operating area, or in the high-load operating area.

In determining the operating range of the engine, if the load Q detected by the load sensor is smaller than a predetermined load determination value Q0, it is determined that the engine is in the low load and medium load operating range, and if the load Q is larger than the predetermined load determining value Q0, the engine is in the high load operating range. .

If it is determined in step S21 that the operating state of the engine is in the low-load and medium-load operating ranges, the first of steps S22 and S23 is performed.
The procedure goes to the clogging determination means 82, and if it is determined that the vehicle is in the high-load operation range, Steps S24 and S24 are executed.
The 25th second clogging determination unit 83 determines the start of regeneration.

In step S22 of the first clogging determining means 82, the pressure ratio Rp is calculated based on the exhaust pressure values PI and PO.
= PI / PO, and in step S23, the pressure ratio Rp is determined to be a pressure ratio determination value R which is a predetermined clogging state determination value.
It is determined whether it is greater than p0.

In this determination, while the pressure ratio Rp is smaller than the predetermined clogging state determination value Rp0, it is determined that the progress of clogging is still small and collection is possible, and it is determined that regeneration has not started (step S26). If it becomes larger, it is determined that the filter 6A for trapping and collecting particulate matter is in a clogged state and the regeneration has started (step S27).

On the other hand, in step S25 of the second clogging judging means 83, the inlet side exhaust pressure PI is detected, and in step S25, the inlet side exhaust pressure PI is a predetermined clogging state judgment value. It is determined whether or not the value is larger than the determination value PI0.

In this determination, while the inlet-side exhaust pressure PI is smaller than the predetermined clogging state determination value PI0, it is determined that the progress of clogging is still small and collection is possible, and it is determined that regeneration is not to be started (step S26). Then, when it becomes larger, it is determined that the filter 6A for collecting and concentrating the particulate matter is in a clogged state and the regeneration is to be started (step S27).

According to the regeneration control method described above, when it is determined that the operating state of the engine is in the low-load and medium-load operating ranges, the pressure ratio RpA and the predetermined pressure ratio determination value Rp0 are determined.
Can be determined by comparison with the above, and when it is determined that the engine operation region is in the high load operation region, the inlet-side exhaust pressure PI and the predetermined inlet-side exhaust pressure determination value PI0 By comparing with, the clogging state of the filter can be determined.

By combining the two clogging judging means and methods in the above-described manner, the mutual disadvantages of the respective clogging judging means and methods can be compensated, and a wide operating range of the engine can be accurately covered. can do.

As another clogging judging means and method, instead of the pressure ratio (Rp), a pressure difference (ΔP = PI
When (PO) reaches a predetermined clogging state determination value ΔP0, there are means, a method, and the like for determining that a clogging state has occurred.

[0054]

As described above, according to the regeneration control method of the diesel particulate filter device according to the present invention, in the regeneration control, when the clogging state of the filter is judged as the start of the regeneration, the engine is stopped. The clogging can be determined by the clogging determination unit most suitable for the operation region by performing clogging determination by different types of clogging determination units according to the operation region, so that clogging can be efficiently performed. The determination can be performed, and the accuracy of the clogging determination can be improved.

In each of the clogging judging means and methods, clogging judgment is not performed in an engine operating region where accuracy and responsiveness are deteriorated or complicated control is required. Since other clogging determination means and methods with high accuracy and simple control are used, the regeneration control as a whole can be simplified and a response delay can be avoided.

[Brief description of the drawings]

FIG. 1 is a diagram showing an example of a configuration of a diesel particulate filter device having a plurality of filters.

FIG. 2 is a diagram showing an example of a configuration of a diesel particulate filter device having a single filter and a bypass passage.

FIG. 3 is a diagram illustrating an example of a configuration of a continuous regeneration type diesel particulate filter device.

FIG. 4 is a diagram showing a control flow of a regeneration control method for the diesel particulate filter device according to the embodiment of the present invention.

FIG. 5 is a diagram showing a control flow of a reproduction start determination according to the embodiment of the present invention.

FIG. 6 is a diagram showing the relationship between the progress of clogging of the filter and the inlet-side exhaust pressure and pressure ratio.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Engine 2 Exhaust passage 4 Switching valve 51 Inlet side pressure sensor 52 Outlet side pressure sensor 6A, 6B, 6C, 6D Filter 7A, 7B, 7C Heater 8 Controller 9 Oxidation catalyst 10A, 10B, 10C, 10D Diesel particulate filter device G Exhaust gas Gc Purified exhaust gas PI Inlet-side exhaust pressure PO Outlet-side exhaust pressure Rp Pressure ratio PI0 Inlet-side exhaust pressure judgment value (predetermined clogging state judgment value) Rp0 pressure ratio judgment value (predetermined clogging state judgment value )

Claims (3)

[Claims] An exhaust gas filter is connected to an exhaust passage of an engine and alternately switches between a filter for collecting particulate matter in the exhaust gas and a filter for oxidizing and regenerating the collected particulate matter. Having a plurality of filters for purifying particulate matter in the filter, a regeneration means for oxidizing and removing particulate matter collected by the filter, and an inlet pressure sensor for detecting an inlet exhaust pressure of the filter. An outlet-side pressure sensor for detecting the outlet-side exhaust pressure of the filter, and regeneration control for controlling the filter regeneration process operation by inputting the inlet-side exhaust pressure and the outlet-side exhaust pressure detected by these exhaust pressure sensors. In a diesel particulate filter device comprising a device, the regeneration control device comprises a plurality of different types of clogging determination means, In the determination of the clogging state, it is determined that the operating region of the engine operating state is determined, the clogging determination unit corresponding to the operation region is selected, and clogging determination is performed by the selected clogging determination unit. A regeneration control method for a diesel particulate filter device. 2. The method according to claim 1, wherein the exhaust gas is connected to an exhaust passage of the engine so as to alternately repeat collection of particulate matter in the exhaust gas and regeneration processing for oxidizing and removing the collected particulate matter. A filter for purifying the substance, a regenerating means for oxidizing and removing particulate matter trapped by the filter, an inlet pressure sensor for detecting an inlet exhaust pressure of the filter, and an outlet exhaust of the filter. A diesel part equipped with an outlet pressure sensor for detecting pressure, and a regeneration control device for inputting the exhaust pressure on the inlet side and the exhaust pressure on the outlet side, which are the detection values of these exhaust pressure sensors, and controlling the regeneration processing operation of the filter. In the curable filter device, the regeneration control device includes a plurality of different types of clogging determination means, and when determining the clogged state of the filter, A diesel particulate filter device that determines an operating region in an engine operating state, selects the clogging determining unit corresponding to the operating region, and performs clogging determination by the selected clogging determining unit. Playback control method. 3. The clogging state of the filter is determined by comparing a pressure ratio, which is a ratio of the inlet-side exhaust pressure to the outlet-side exhaust pressure, with a predetermined pressure ratio determination value. A first clogging judging means, and a second clogging judging means for judging a clogged state of the filter by comparing the inlet-side exhaust pressure with a predetermined inlet-side exhaust pressure judgment value; When the clogging state is determined, an operation region of the engine is determined, and when it is determined that the operation region of the engine is in the low load operation region and the medium load operation region, the first clogging determination unit is used. The clogging determination is made in step (1), and if it is determined that the operation region of the engine is in the high-load operation region, clogging determination is performed by the second clogging determination unit. Diesel patties described in Reproduction control method of the Interview filter device.