JP7209594B2 - Control device - Google Patents

Description

The present invention relates to control devices.

DPFs (Diesel Particulate Filters) and GPFs (Gasoline Particulate Filters) are known as filters for vehicles that remove particulate matter such as soot and oil-derived ash contained in exhaust gas discharged from an engine. In such a filter, particulate matter is removed from the exhaust gas by capturing the particulate matter with holes formed in the filter (eg, Patent Document 1).

JP 2015-222028 A

Such filters become clogged with particulate matter with continued use.

An object of the present invention is to provide a control device capable of suppressing clogging of a filter.

In order to solve the above problems, a control device according to the present invention includes a filter provided downstream of an engine and provided in an exhaust passage through which gas discharged from the engine flows, and a filter provided downstream of the filter. a throttle valve that is provided upstream of the engine and that variably adjusts the flow rate of intake air to the engine; and a valve that controls the opening and closing of the first valve and the throttle valve. and a control unit, wherein the valve control unit controls the first valve to a closed state to increase the pressure of the gas in the exhaust passage, and then controls the throttle valve to an open state. to reverse the gas in the exhaust passage.

The valve control unit may control the first valve to a closed state to increase the pressure of the gas in the exhaust passage based on the stop of fuel supply to the engine.

The valve control unit may control the throttle valve to an open state to cause the gas in the exhaust passage to flow backward based on the stop of the engine.

a return pipe having one end connected between the engine and the filter and the other end connected between the engine and the throttle valve; and a second valve, wherein the valve control unit controls the first valve and the second valve to a closed state to increase the pressure of the gas in the exhaust passage, The second valve and the throttle valve may be controlled to open to allow the gas in the exhaust passage to flow backward.

A reservoir may be provided on the upstream side of the filter to retain the particulate matter captured by the filter.

According to the present invention, filter clogging can be suppressed.

It is a schematic diagram for explaining a control device. 10 is a flowchart showing the flow of blow-off control processing;

Preferred embodiments of the present invention will be described in detail below with reference to the accompanying drawings. The dimensions, materials, and other specific numerical values shown in these embodiments are merely examples for facilitating understanding of the invention, and do not limit the invention unless otherwise specified. In the present specification and drawings, elements having substantially the same function and configuration are given the same reference numerals to omit redundant description, and elements that are not directly related to the present invention are omitted from the drawings. do.

FIG. 1 is a schematic diagram showing a control device 100. As shown in FIG. In FIG. 1, the flow of signals is indicated by dashed arrows. As shown in FIG. 1 , the control device 100 includes an engine 1 and an ECU (Engine Control Unit) 101 .

The engine 1 is a horizontally opposed engine in which a plurality of cylinders 2 are arranged to face each other. However, the engine 1 is not limited to a horizontally opposed engine. The ECU 101 is composed of a microcomputer including a central processing unit (CPU), a ROM storing programs and the like, a RAM as a work area, and the like, and controls the engine 1 as a whole. The ECU 101 also functions as a condition determination unit 103 that determines whether or not a fuel cut condition (to be described later) is satisfied, a fuel control unit 104 that controls fuel supply to the engine 1, and a valve control unit 105 that controls the opening and closing of each valve (to be described later). do. In addition, below, the configuration and processing related to the present embodiment will be described in detail, and the description of the configuration and processing irrelevant to the present embodiment will be omitted.

A piston 3 is arranged in the cylinder 2 . One end of a connecting rod 4 is connected to the piston 3 . The other end of connecting rod 4 is connected to crankshaft 5 . The crankshaft 5 is rotatably supported by bearings (not shown) in the crank chamber 6 .

A cylinder head 7 is provided at the end of the cylinder 2 opposite to the crankshaft 5 . An intake port and an exhaust port (not shown) are formed in the cylinder head 7 . The intake port and the exhaust port pass through the cylinder head 7 from the inside (combustion chamber 8 side) to the outside of the cylinder head 7 .

An intake passage 9 including an intake manifold communicates with the intake port. An air cleaner 10 and a throttle valve 11 are provided in the intake passage 9 in order from the upstream side.

An exhaust passage 12 including an exhaust manifold communicates with the exhaust port. The exhaust passage 12 is provided with a purification device 13, a first valve 14, and a muffler 15 in this order from upstream.

The purification device 13 also has a three-way catalyst 16 , a reservoir 17 and a filter 18 . The three-way catalyst 16 includes catalytic components such as platinum (Pt), palladium (Pd), rhodium (Rh), and the like. The three-way catalyst 16 removes hydrocarbons, carbon monoxide, and nitrogen oxides in the exhaust gas discharged from the exhaust port.

The filter 18 is provided downstream of the three-way catalyst 16 . Further, the filter 18 is, for example, a GPF (Gasoline Particulate Filter) that is configured by a particulate filter and collects soot and ash in the exhaust gas. Storage portion 17 is provided between three-way catalyst 16 and filter 18 . The reservoir 17 is provided vertically downward in the purification device 13 . Further, the bottom surface of the purifier 13 is formed to be deeper than the portion where the reservoir 17 is not provided.

Further, the purification device 13 is provided with a differential pressure sensor 19 . The differential pressure sensor 19 detects the pressure difference (differential pressure) between the upstream side and the downstream side of the filter 18 . Further, the controller 100 is provided with an accelerator opening sensor 102 . These differential pressure sensor 19 and accelerator opening sensor 102 are connected to the ECU 101 and output to the ECU 101 a signal indicating the detected value of the accelerator opening.

A high pressure EGR (HPEGR) flow path 21 communicates upstream of the purification device 13 in the exhaust passage 12 and downstream of the throttle valve 11 in the intake passage 9 . An HPEGR cooler 22 is provided in the HPEGR flow path (recirculation pipe) 21 , and the exhaust gas cooled by the HPEGR cooler 22 is recirculated to the combustion chamber 8 . The HPEGR valve (second valve) 23 is provided in the HPEGR flow path 21 and controls the flow rate of exhaust gas recirculated to the combustion chamber 8 by adjusting the width of the HPEGR flow path 21 . By recirculating the exhaust gas to the combustion chamber 8 in this way, it is possible to reduce the oxygen concentration of the intake air, lower the combustion temperature of the fuel, and suppress the generation of NOx (nitrogen oxides) and the like.

In this embodiment, when the condition determining unit 103 determines that a predetermined fuel cut condition is satisfied, the fuel control unit 104 stops the supply of fuel to the engine 1 (fuel cut). is executed. The predetermined condition is, for example, that the vehicle is decelerating (vehicle speed > 0) and the opening of the accelerator indicated by the accelerator opening signal obtained from the accelerator opening sensor 102 is zero.

By the way, when the filter 18 is clogged with soot or ash (hereinafter referred to as particulate matter 20), the pressure difference between the upstream side and the downstream side of the filter 18 increases. When the pressure difference between the upstream side and the downstream side of the filter 18 increases, it becomes difficult for the exhaust gas to flow into the exhaust passage 12, and the pressure in the combustion chamber 8 becomes difficult to decrease, and the performance of the engine 1 may deteriorate.

Therefore, in the present embodiment, blow-off control is performed to remove the particulate matter 20 deposited on the filter 18 . The blow-off process is executed when the engine 1 stops (when the vehicle stops) when the above-described fuel cut process is executed. Specifically, when the fuel cut process is executed, the valve control unit 105 controls the first valve 14 and the HPEGR valve 23 to be in a closed state (or to have a smaller opening degree). As a result, the pressure on the upstream side of the first valve 14 in the exhaust passage 12 and the pressure on the upstream side of the HPEGR valve 23 in the HPEGR flow path 21 are increased. At this time, the valve control unit 105 controls the throttle valve 11 so that the pressure upstream of the first valve 14 in the exhaust passage 12 and the pressure upstream of the HPEGR valve 23 in the HPEGR flow path 21 do not decrease. Adjust the opening. For example, the valve control unit 105 performs control so that the opening degree of the throttle valve 11 is reduced before the engine 1 stops. Then, based on the stop of the engine 1, the valve control unit 105 controls the HPEGR valve 23 and the throttle valve 11 to open (or to increase the degree of opening). As a result, the compressed gas on the upstream side of the first valve 14 in the exhaust passage 12 and on the upstream side of the HPEGR valve 23 in the HPEGR flow path 21 flows back toward the intake passage 9 side. . Then, the particulate matter 20 deposited on the filter 18 is blown away upstream of the filter 18 by the gas that flows back through the filter 18 .

FIG. 2 is a flow chart showing the flow of blow-off control processing. The ECU 101 executes a series of processes shown in FIG. 2 at predetermined interrupt timings.

First, the condition determination unit 103 determines whether a predetermined fuel cut condition is satisfied (S10). As a result, when it is determined that the predetermined fuel cut condition is satisfied, the process proceeds to S12, and when it is determined that the predetermined fuel cut condition is not satisfied, the process proceeds to S18. The predetermined fuel cut condition is, for example, during deceleration (vehicle speed > 0) as described above, and is satisfied when the accelerator opening indicated by the accelerator opening signal obtained from the accelerator opening sensor 102 is zero. can be done.

If the fuel cut condition is satisfied (YES in S10), the fuel control unit 104 executes fuel cut processing to stop the supply of fuel to the engine 1 (S12). The valve control unit 105 controls (S14) the first valve 14 and the HPEGR valve 23 to close (or reduce the degree of opening), and the ECU 101 controls the fuel flow indicating that the fuel cut is being executed. A cut flag is turned on (S16). Even during execution of the fuel cut process, the engine 1 is rotating due to the running of the vehicle. Therefore, the valve control unit 105 controls the first valve 14 and the HPEGR valve 23 to be in a closed state (or to reduce the opening degree), so that the pressure on the upstream side of the first valve 14 in the exhaust passage 12 , and the pressure on the upstream side of the HPEGR valve 23 in the HPEGR flow path 21 rises. Further, at this time, the valve control unit 105 controls the throttle valve so that the pressure on the upstream side of the first valve 14 in the exhaust passage 12 and the pressure on the upstream side of the HPEGR valve 23 in the HPEGR flow path 21 do not decrease. Adjust the opening of 11. For example, as described above, the valve control unit 105 controls the opening of the throttle valve 11 to be smaller before the engine 1 stops.

If the fuel cut condition is not satisfied (YES in S10), the ECU 101 determines to stop the engine 1 (S18). As a result, when it is determined that the engine 1 has stopped, the process proceeds to S20, and when it is determined that the engine 1 has not stopped, the blow-off control process ends.

If the engine 1 is stopped (YES in S18), the ECU 101 determines whether the fuel cut flag is ON (S20). As a result, when it is determined that the fuel cut flag is on, the process proceeds to S22, and when it is determined that the fuel cut flag is not on, the blow-off control process ends.

If the fuel cut flag is ON (YES in S20), the valve control unit 105 controls the HPEGR valve 23 and the throttle valve 11 to open (or to increase the degree of opening) (S22). As a result, the compressed gas on the upstream side of the first valve 14 in the exhaust passage 12 and on the upstream side of the HPEGR valve 23 in the HPEGR flow path 21 flows back toward the intake passage 9 side. . Then, the particulate matter 20 deposited on the filter 18 is blown away upstream of the filter 18 by the gas that flows back through the filter 18 . At least part of the blown particulate matter 20 falls into the storage section 17 and is stored. By blowing off the particulate matter 20 accumulated in the filter 18 from the filter 18 in this manner, clogging of the filter 18 is eliminated.

In this embodiment, the above-described blow-off process is executed each time the fuel cut condition is satisfied. Therefore, even if part of the particulate matter 20 stored in the storage part 17 flows downstream and accumulates on the filter 18, it can be removed from the filter 18 again by the subsequent blowing process. . In addition, the particulate matter 20 contained in the exhaust gas adheres to the particulate matter 20 stored in the storage portion 17, so that the particulate matter 20 stored in the storage portion 17 gradually increases over time. Become. Then, the particulate matter 20 stored in the storage portion 17 and grown to a size of a predetermined size or larger is less likely to be blown off to the filter 18 by the flow of the exhaust gas. Therefore, it becomes possible to use the filter 18 continuously for a long period of time.

Although the preferred embodiments of the present invention have been described above with reference to the accompanying drawings, it goes without saying that the present invention is not limited to such embodiments. It is obvious that a person skilled in the art can conceive of various modifications or modifications within the scope of the claims, and it should be understood that these also belong to the technical scope of the present invention. be done.

For example, an ECV (Exhaust Control Valve) provided between the purification device 13 and the muffler 15 may be applied as the first valve 14 provided downstream of the filter 18 in the above embodiment. When an ECV is provided, an LPEGR flow path having one end connected between the purification device 13 and the ECV and the other end connected between the air cleaner 10 and the throttle valve 11 is provided. An LPEGR cooler and an LPEGR valve may be provided from the side. The exhaust gas cooled by the LPEGR cooler is recirculated to the combustion chamber 8 together with the intake air that has passed through the air cleaner 10 . The LPEGR valve is provided in the LPEGR flow path, and controls the flow rate of the exhaust gas recirculated to the combustion chamber 8 by adjusting the width of the LPEGR flow path.

In this case, the valve control unit 105 controls the first valve 14, the HPEGR valve 23, and the LPEGR valve to the closed state (or to reduce the opening degree) in the fuel cut process, and then, in the blow-off process, The HPEGR valve 23 and the throttle valve 11 may be controlled to be in an open state (or so that the degree of opening is increased). By recirculating the exhaust gas to the combustion chamber 8 in this manner, as in the HPEGR flow path 21, it is possible to reduce the oxygen concentration and the combustion temperature of the fuel, thereby suppressing the generation of NOx and the like. In addition, although the LPGR flow path may have a delayed response compared to the HPEGR flow path 21, it can circulate a large amount of low-temperature exhaust gas. Alternatively, the engine 1 may be a diesel engine and the first valve 14 may be applied to an exhaust brake.

Also, in the above embodiment, the case where the reservoir 17 is provided has been shown, but the structure of the reservoir 17 is not essential. Further, in the above-described embodiment, the storage portion 17 is provided between the three-way catalyst 16 and the filter 18, but the present invention is not limited to this. That is, when the reservoir 17 is provided, the reservoir 17 may be provided at least upstream of the filter 18, and its position is not particularly limited. Further, for example, if the reservoir 17 is configured to be detachable, it becomes possible to easily discard the particulate matter 20 stored in the reservoir 17 .

Further, in the above-described embodiment, when the fuel cut process is executed, the first valve 14 and the HPEGR valve 23 are controlled to be in a closed state (or so that the degree of opening is reduced), and the first valve in the exhaust passage 12 is controlled. 1 and the pressure upstream of the HPEGR valve 23 in the HPEGR flow path 21 are respectively increased, but the present invention is not limited to this. That is, when the engine 1 is in operation (injecting and burning fuel), the valve control unit 105 causes the first valve 14 and the HPEGR valve 23 to close (or reduce the opening degree). ), and then control the HPEGR valve 23 and the throttle valve 11 to the open state (or to increase the degree of opening).

Further, in the above-described embodiment, the blow-off process is executed each time the fuel cut condition is satisfied and the engine 1 is stopped, but the present invention is not limited to this. For example, the ECU 101 may determine whether to execute the blow-off process based on the differential pressure detected by the differential pressure sensor 19 . That is, the ECU 101 may decide to execute the blow-off process when the differential pressure detected by the differential pressure sensor 19 exceeds a preset threshold value.

INDUSTRIAL APPLICABILITY The present invention can be used for vehicle control devices.

1 Engine 9 Intake Passage 11 Throttle Valve 12 Exhaust Passage 14 First Valve 17 Reservoir 18 Filter 20 Particulate Matter 21 HPEGR Flow Path (Return Pipe)
23 HPEGR valve (second valve)
100 control device 105 valve control unit

Claims (5)

a filter provided downstream of the engine and provided in an exhaust passage through which gas discharged from the engine flows;
a first valve provided downstream of the filter;
a throttle valve provided upstream of the engine and variably adjusting the flow rate of intake air to the engine;
a valve control unit that controls opening and closing of the first valve and the throttle valve;
with
The valve control unit is
A control device that controls the first valve to a closed state to increase the pressure of the gas in the exhaust passage, and then controls the throttle valve to an open state to reverse the flow of the gas in the exhaust passage. . 2. The valve control unit according to claim 1, wherein the valve control unit controls the first valve to a closed state to increase the pressure of the gas in the exhaust passage based on the stop of fuel supply to the engine. Control device as described. 3. The control device according to claim 1, wherein the valve control unit controls the throttle valve to an open state to cause the gas in the exhaust passage to flow backward based on the stop of the engine. a return pipe having one end connected between the engine and the filter and the other end connected between the engine and the throttle valve;
a second valve provided in the return pipe and controlled to open and close by the valve control unit;
with
The valve control unit closes the first valve and the second valve to increase the pressure of the gas in the exhaust passage, and then closes the second valve and the throttle valve. 4. The control device according to any one of claims 1 to 3, wherein the opening is controlled to cause the gas in the exhaust passage to flow backward. 5. The control device according to any one of claims 1 to 4, further comprising a reservoir provided on the upstream side of the filter to retain particulate matter trapped in the filter.

Images