JP2005016384A - Exhaust emission control system of internal combustion engine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To solve such a problem that since a delivery function of a feed pump is low at starting of an engine, when a fuel is leaked from a reducing agent additive device (additive fuel supply passage or fuel additive injector) at starting of the engine, a common rail pressure cannot maintain a pressure sufficient for starting whereby starting failure occurs. <P>SOLUTION: In this exhaust emission control system of internal combustion engine, when ON time of a starter switch reaches a predetermined time, or when the number of ON of the starter switch reaches a predetermined number, ECU 5 determines that the starting failure occurs, whereby an FCV 58 arranged to an upstream side of the additive fuel supply passage 56 is forcedly closed. Accordingly, the starting failure in which the common rail pressure can not maintain the pressure sufficient for starting is prevented, whereby an engine 1 is normally operated. Since the starting failure is detected based on the ON time and the number of ON of the starter switch, even when an air-fuel ratio of an exhaust passage is unstable and an oxygen concentration level is high, the starting failure can be surely detected. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an exhaust gas purification system for an internal combustion engine (hereinafter referred to as an engine) in which a part of fuel pumped by a fuel injection device is added as a reducing agent upstream of a reduction purification device.
[0002]
BACKGROUND OF THE INVENTION
For example, when NOx is reduced by a reduction purification device (NOx reduction catalyst) disposed in the exhaust passage to purify exhaust gas, an additive serving as a reducing agent is required to make the reduction purification device function.
Therefore, a reducing agent addition device that injects fuel (for example, hydrocarbons such as light oil and gasoline) as a reducing agent into the exhaust passage upstream of the reduction purification device is known. The reducing agent addition device includes a fuel addition injector that adds fuel to the upstream side of the reduction purification device, and an added fuel supply passage that supplies fuel to the fuel addition injector.
[0003]
However, there is a possibility that fuel may leak from the reducing agent addition device (added fuel supply passage or fuel addition injector) due to some abnormality.
Therefore, if the pressure difference between the fuel inflow side and the outflow side exceeds the specified pressure, a flow limiter type shut-off valve that closes the added fuel supply passage with that pressure difference is arranged upstream of the added fuel supply passage. When a situation where fuel leaks from the apparatus occurs, a technique for cutting the fuel supplied to the reducing agent addition apparatus by closing the shut-off valve due to the differential pressure has been proposed (not a well-known technique, patent document 1).
[0004]
Also, in the unlikely event that fuel leaks from the reducing agent addition device into the exhaust passage due to some abnormality, a technique has been proposed for detecting the leakage by a change in the air-fuel ratio in the exhaust passage (not a well-known technique, Patent Document 2).
[0005]
[Patent Document 1]
Japanese Patent Application No. 2002-053510
[Patent Document 2]
Japanese Patent Application 2002-049533
[0006]
[Problems to be solved by the invention]
In a reducing agent addition device that injects a part of the fuel pumped by the fuel injection device to the upstream side of the reduction purification device (NOx reduction catalyst), in the unlikely event that the fuel leaks from the reducing agent addition device due to some abnormality In some cases, the capacity of the fuel injection device is reduced.
[0007]
The specific malfunction will be described with reference to FIG.
FIG. 6 shows a fuel that is mounted on a supply pump J1 of a common rail type fuel injection device and is regulated to a predetermined pressure on the low pressure side of a regulator valve J3 of a feed pump J2. What is supplied to J5 and the fuel addition injector J6).
When the engine is started (when the starter is operated and before the engine completes explosion), the discharge capacity of the feed pump J2 is low. For this reason, if the fuel leaks from the reducing agent addition device J4 (added fuel supply passage J5 or fuel addition injector J6) at the time of starting the engine, even if the common rail pressure cannot maintain the pressure sufficient for starting or is in a state where it can start. A start-up failure in which startability deteriorates due to a decrease in the common rail pressure occurs.
[0008]
This will be described with reference to FIG.
The discharge flow rate (total amount) of the feed pump J2 is: (1) “pump discharge flow rate” sent to the high pressure pump J7 + (2) “exhaust gas addition valve injection flow rate” sent to the reducing agent addition device J4 + (3) high pressure pump “Cam chamber circulation flow rate” sent to the cam chamber J8 of J7 + (4) “Circulation flow rate by the regulator valve J3” circulating through the regulator valve J3 for adjusting the discharge pressure of the feed pump J2.
Since the feed pump J2 is driven by the engine together with the high-pressure pump J7, the discharge flow rate (total amount) of the feed pump J2 increases as the rotational speed of the engine increases. That is, when starting the engine, the total amount of fuel discharged from the feed pump J2 is small.
[0009]
In the engine starting speed range (starting speed), as shown by a circle A in FIG. 7, the discharge flow rate (total amount) of the feed pump J2 is (2) “exhaust addition valve injection flow rate (maximum value)”. Below.
For this reason, if fuel leaks from the fuel addition injector J6, (1) “pump discharge flow rate” cannot be secured in the engine rotation speed range (starting speed) and the above-mentioned starting failure occurs. End up.
[0010]
In order to cope with such a problem, the technique disclosed in Patent Document 1 described above is a technique for shutting off the fuel supply to the reducing agent adding device with a flow limiter type shut-off valve. When the supply pressure of the fuel sent to the equipment is low, the flow rate through the flow limiter type shut-off valve is small, and even if leakage occurs in the reducing agent addition device, the shut-off function of the shut-off valve does not operate and a starting failure occurs Resulting in.
[0011]
On the other hand, the technique of Patent Document 2 described above is a technique for detecting fuel leakage by the reducing agent addition device based on a change in the air-fuel ratio in the exhaust passage. However, at the time of starting, combustion is not sufficiently performed, the change of the air-fuel ratio is unstable, and the oxygen concentration is at a high level. For this reason, at the time of start-up, it is difficult to detect fuel leakage by the reducing agent addition device from the air-fuel ratio.
[0012]
OBJECT OF THE INVENTION
The present invention has been made in view of the above circumstances, and its purpose is to prevent the leakage of fuel from the reducing agent addition device even in the event that fuel leaks from the reducing agent addition device due to any abnormality. The present invention provides an engine exhaust purification system that can start an engine.
[0013]
[Means for Solving the Problems]
[Means of Claim 1]
The exhaust gas purification system that employs the means of claim 1 electrically forcibly closes the fuel cutoff valve provided upstream of the added fuel supply passage when the engine start failure is detected.
By providing in this way, even if there is a situation where fuel leaks from the reducing agent addition device (added fuel supply passage or fuel addition injector) due to some abnormality, the fuel cutoff valve is forcedly closed to the reducing agent addition device. Since the fuel supply is stopped, it is possible to prevent a decrease in the fuel supply pressure in the fuel injection device, thereby avoiding a starting failure.
[0014]
[Means of claim 2]
The exhaust gas purification system employing the means of claim 2 detects a starting failure when the engine does not completely explode even when the starter switch has been on for a predetermined time.
As described above, since the start failure is detected by the on-time of the starter switch, the start failure can be reliably detected even when the air-fuel ratio in the exhaust passage is unstable and the oxygen concentration is at a high level. .
[0015]
[Means of claim 3]
The exhaust gas purification system employing the means of claim 3 detects a starting failure when the engine does not completely explode even if the starter switch has been turned on a predetermined number of times.
In this way, since the start failure is detected by the number of times the starter switch is turned on, the start failure is surely ensured even when the air-fuel ratio in the exhaust passage is unstable and the oxygen concentration is at a high level. It can be detected.
[0016]
[Means of claim 4]
The exhaust gas purification system adopting the means of claim 4 is an operation unnecessary region of the reducing agent addition device (for example, the engine speed) from the operating state of the engine (for example, the engine speed, the fuel injection amount to the engine, the throttle opening, etc.). When it is determined that the fuel cutoff valve is at the time of starting, etc., the fuel cutoff valve provided upstream of the added fuel supply passage is electrically forcibly closed.
When the engine is started (before the complete explosion of the engine), it is an operation unnecessary region of the reducing agent addition device in which the fuel addition injector is closed. For this reason, even if a situation occurs in which fuel leaks from the reducing agent addition device (added fuel supply passage or fuel addition injector), fuel leakage can be prevented when the engine is started, and starting failure due to fuel leakage can be avoided.
[0017]
DETAILED DESCRIPTION OF THE INVENTION
The embodiment of the present invention will be described using two examples and modifications. The first embodiment shows an embodiment to which the first invention (the invention according to claims 1 to 3) is applied, and the second embodiment is the second invention (the invention according to claim 4). The Example to which is applied is shown.
[0018]
[First embodiment]
A first embodiment will be described with reference to FIGS.
An exhaust purification system includes a fuel injection device that injects fuel into an engine, an exhaust purification device that includes a NOx reduction catalyst (which corresponds to a reduction purification device) that reduces and purifies exhaust gas, and an exhaust passage upstream of the NOx reduction catalyst. A reducing agent addition device for adding fuel as a reducing agent;
A fuel cutoff valve according to the present invention and a control device (ECU in this embodiment) for controlling the fuel cutoff valve will be described later.
Each of the above components will be sequentially described below.
[0019]
(Description of fuel injection device)
First, the fuel injection device of the present embodiment will be described with reference to FIG. The fuel injection device shown in this embodiment is a schematic view of a common rail fuel injection device.
A common rail type fuel injection device is a device that injects fuel into each cylinder of an engine (for example, a diesel engine) 1 and includes a common rail 2, an injector 3, a supply pump 4, an ECU 5 (engine control unit), and the like. In addition, although ECU5 shown in this Example is an example which incorporates EDU (drive unit) which drives each electrical component, it may arrange | position EDU outside ECU5.
[0020]
The common rail 2 is a pressure accumulating main body that accumulates high-pressure fuel supplied to the injector 3, and discharge of the supply pump 4 that pumps high-pressure fuel through the high-pressure pump pipe 6 so that the common rail pressure corresponding to the fuel injection pressure is accumulated. In addition to being connected to the outlet, a plurality of injector pipes 7 for supplying high-pressure fuel to each injector 3 are connected. The leak fuel from the injector 3 and the leak fuel from the supply pump 4 are returned to the fuel tank 9 via the leak pipe 8.
[0021]
A pressure limiter 11 is attached to a relief pipe 10 that returns fuel from the common rail 2 to the fuel tank 9. The pressure limiter 11 is a pressure safety valve, which opens when the fuel pressure in the common rail 2 exceeds the limit set pressure, and suppresses the fuel pressure in the common rail 2 below the limit set pressure.
Further, a pressure reducing valve (not shown) is attached to the common rail 2. This pressure reducing valve is opened by a valve opening instruction signal given from the ECU 5 and causes the high pressure fuel in the common rail 2 to overflow through the leak pipe 8 to rapidly reduce the common rail pressure. As described above, by mounting the pressure reducing valve on the common rail 2, the ECU 5 can quickly control the common rail pressure to a pressure corresponding to the vehicle running state.
[0022]
The injector 3 is mounted in each cylinder of the engine 1 and supplies fuel into each cylinder. The injector 3 is connected to the downstream ends of a plurality of injector pipes 7 branched from the common rail 2 and accumulated in the common rail 2. In addition, a fuel injection nozzle that injects the high-pressure fuel into each cylinder and an electromagnetic valve that performs lift control of the needle accommodated in the fuel injection nozzle are mounted.
[0023]
The configuration of the supply pump 4 will be described with reference to FIG.
The supply pump 4 sends fuel compressed to a high pressure to the common rail 2, and includes a feed pump 12 (disclosed in a state of 90 ° expansion in FIG. 4), a regulator valve 13, a fuel metering valve (hereinafter referred to as SCV). 14) It is constituted by a high-pressure pump 15.
[0024]
The feed pump 12 is a trochoid pump that is rotationally driven by the camshaft 16. When the trochoid pump is driven, the fuel sucked from the fuel inlet 17 is supplied to the high-pressure pump 15 via the SCV 14.
The camshaft 16 is rotationally driven by a crankshaft 18 of the engine 1 as shown in FIG.
[0025]
The regulator valve 13 is disposed in a fuel passage that communicates the discharge side (high pressure side) and the supply side (low pressure side) of the feed pump 12, and opens when the discharge pressure of the feed pump 12 rises to a predetermined pressure. This is to prevent the discharge pressure of the pump 12 from exceeding a predetermined pressure.
[0026]
The SCV 14 is a valve that adjusts the amount of fuel pumped to the common rail 2 by adjusting the amount of fuel sucked into the high-pressure pump 15 by being controlled by a pump drive signal from the ECU 5. The common rail pressure is adjusted by adjusting the discharge amount of the fuel pumped to the common rail 2. That is, the ECU 5 can control the common rail pressure to a pressure corresponding to the vehicle running state by controlling the SCV 14.
[0027]
The high-pressure pump 15 of this embodiment is composed of one or a plurality of (two in this embodiment) plunger pumps 19 that are reciprocally driven by a camshaft 16, and a pressurizing chamber 21 of the plunger pump 19. A suction valve 22 that supplies fuel to the pressure chamber 21 and a discharge valve 23 that discharges the fuel compressed in the pressurizing chamber 21 toward the common rail 2 are provided.
[0028]
The plunger pump 19 is pressed against the eccentric cam 24 that rotates eccentrically with the rotation of the camshaft 16, a cam ring 26 that is rotatably mounted around the eccentric cam 24 via a sliding bearing (bush) 25, and the cam ring 26. A plunger 27 that reciprocates and a spring 28 that presses the plunger 27 against the cam ring 26 are configured. The cam chamber 29 in which these are disposed is supplied with fuel from the feed pump 12 through a fuel passage 32 in which a throttle 31 is formed, so that the cam chamber 29 is filled with fuel. The surplus fuel in the cam chamber 29 is discharged from the fuel outlet 33 and returned to the fuel tank 9.
[0029]
The ECU 5 includes a CPU, a RAM, a ROM, and the like (not shown), and performs various arithmetic processes based on a program stored in the ROM and sensor signals (vehicle driving state) read into the RAM. I do.
An example of a specific calculation is as follows. For each fuel injection, the ECU 5 determines each cylinder based on a program stored in the ROM and a sensor signal (vehicle operating state) read into the RAM. The target injection amount, the injection mode, and the valve opening timing of the injector 3 are determined.
[0030]
The ECU 5 includes an accelerator opening sensor 41 for detecting the accelerator opening, a rotation speed sensor 42 for detecting the rotational speed of the engine 1, and a cooling water temperature for detecting the engine cooling water temperature as means for detecting the driving state of the vehicle. A sensor 43, a common rail pressure sensor 44 for detecting the common rail pressure, and other sensors 45 are connected.
[0031]
(Explanation of exhaust purification system)
The exhaust emission control device will be described with reference to FIG.
As shown in FIG. 1, an exhaust pipe 51 is connected to the engine 1, and an exhaust purification device is disposed in the middle of an exhaust passage formed in the exhaust pipe 51.
The exhaust purification device includes a NOx reduction catalyst 52 (corresponding to a reduction purification device) and a diesel particulate filter 53 disposed downstream thereof.
[0032]
The NOx reduction catalyst 52 includes a single component selected from an alkali metal such as potassium, sodium or lithium, an alkaline earth metal such as barium or calcium, or a rare earth such as cesium on a support such as alumina, and a noble metal such as platinum. It is supported.
The NOx reduction catalyst 52 stores NOx when the air-fuel ratio of the inflowing exhaust gas is lean, and reduces NOx when the oxygen concentration of the inflowing exhaust gas decreases.
On the other hand, the diesel particulate filter 53 is made of, for example, a filter made of metal ceramics or porous ceramics, and collects particulate matter contained in the exhaust gas.
[0033]
(Description of reducing agent addition device)
The reducing agent addition apparatus will be described with reference to FIG.
The reducing agent addition device supplies a fuel addition injector 55 that adds fuel as a reducing agent into the exhaust passage on the upstream side of the NOx reduction catalyst 52, and supplies a part of the fuel pressure-fed by the fuel injection device to the fuel addition injector 55. And an additional fuel supply passage 56.
[0034]
The fuel addition injector 55 is connected to the downstream end of the addition fuel supply passage 56, and injects the fuel supplied by the addition fuel supply passage 56 into the exhaust passage on the upstream side of the NOx reduction catalyst 52, and this It is equipped with a solenoid that performs lift control of the fuel injection nozzle. The fuel addition injector 55 is intermittently injected by a control signal from the ECU 5.
The ECU 5 calculates the drive timing for driving the fuel addition injector 55 based on the rotational speed signal of the engine 1 and the injection amount of fuel injected from the injector 3 into each cylinder. Then, according to the calculated drive timing, the solenoid of the fuel addition injector 55 is driven to control the fuel addition injector 55.
[0035]
The added fuel supply passage 56 is a fuel passage that connects the fuel addition injector 55 to the low pressure side of the regulator valve 13 that has been regulated to a predetermined pressure, and as shown in FIGS. 4 is formed by an added fuel upstream passage 56 a formed in the housing 4, an outflow port 57 provided at the outlet of the added fuel upstream passage 56 a, and an added fuel supply pipe 56 b that connects the fuel added injector 55.
[0036]
[Characteristics of the first embodiment]
In the above configuration, as described in the section “Problems to be Solved by the Invention”, if a fuel leakage occurs from the reducing agent addition device (the fuel addition injector 55 or the added fuel supply passage 56) due to some abnormality, by any chance. The common rail pressure cannot maintain a pressure sufficient for starting, or even if the common rail pressure is in a startable state, the startability is deteriorated due to a decrease in the common rail pressure.
[0037]
Therefore, in the exhaust purification system of this embodiment, a fuel cutoff valve (hereinafter referred to as FCV) 58 that can be electrically forcibly closed is disposed upstream of the added fuel supply passage 56, and when the ECU 5 detects a start failure, the FCV 58 Is forcibly closed. The ECU 5 corresponds to the control device of the present invention.
[0038]
As shown in FIG. 3, the FCV 58 of the present embodiment can open and close the added fuel upstream passage 56 a formed in the housing of the supply pump 4, and is assembled to the supply pump 4.
The FCV 58 includes a valve that opens and closes the added fuel upstream passage 56a and a solenoid that drives the valve.
[0039]
The FCV 58 can be forcibly closed regardless of the discharge pressure of the feed pump 12. However, the FCV 58 of this embodiment cannot be opened from the closed state when the engine 1 starts operation and the discharge pressure of the feed pump 12 increases, and the operation of the engine 1 starts. The valve is opened by previously turning on the FCV58 solenoid.
[0040]
The ECU 5 has means for detecting a start failure when the engine 1 is started, and is provided to forcibly close the FCV 58 when the start failure is detected.
The ECU 5 of this embodiment detects, as a means for detecting a start failure when the engine 1 is started, (1) a start failure when the engine 1 does not completely explode even when the starter switch ON time reaches a predetermined time. 2) It is provided to detect a starting failure when the engine 1 does not completely explode even if the starter switch has been turned ON a predetermined number of times. At least one of the above (1) and (2) causes a starting failure. Is detected, the FCV 58 is turned off to forcibly close the upstream side of the added fuel supply passage 56.
[0041]
Next, an example of control of the FCV 58 by the ECU 5 will be described with reference to the flowchart of FIG.
When the ignition key is turned on (start), it is determined whether or not the starter switch is turned on (step S1). If the determination result in step S1 is YES, it is determined whether or not there is an abnormality history in the storage device of the ECU 5 (step S2). If this determination is NO, FCV 58 is turned on (step S3). Note that once the FCV 58 is turned on, the ECU 5 keeps turning on the FCV 58 until it is determined to turn it off.
[0042]
Next, it is determined whether or not the starter switch has been ON for a predetermined time (for example, 20 seconds) or longer (step S4). The starter switch ON time starts counting when the starter switch is first turned on after the previous operation of the engine 1 is stopped, and integrates the starter switch ON time. It is reset when the engine 1 is completely detonated and operated. If the determination result in step S4 is YES, it is determined that a starting failure has occurred, and the FCV 58 is turned off (step S5). Subsequently, the abnormality history is stored in the ECU 5 (step S6), and then the process returns. Note that once the FCV 58 is turned off, the ECU 5 keeps turning off the FCV 58 until it is determined to turn it on.
[0043]
If the determination result in step S4 is NO, it is determined whether or not the starter switch has been turned ON a predetermined number of times (for example, 5 times) (step S7). The number of times the starter switch is turned on starts counting when the starter switch is first turned on after the operation of the engine 1 was stopped last time. Then it is reset. If the result of this determination is YES, it is determined that a starting failure has occurred, and as in the case of YES in step S4, FCV 58 is turned off in step S5, the abnormality history is stored in ECU 5 in step S6, and then the process returns.
[0044]
If the determination result in step S7 is NO, it is determined that no malfunction has occurred and the process returns.
On the other hand, if the determination result in step S1 is NO, it is determined whether or not the engine 1 is in operation (step S8). If the determination result is YES, it is determined that the engine 1 has started, the starter switch ON time and the starter switch ON count are reset (step S9), and then the process returns.
If the determination result in step S2 is YES and the determination result in step S8 is NO, FCV 58 is turned off (step S10), and then the process returns.
[0045]
[Effects of the first embodiment]
In the unlikely event that fuel leaks from the reducing agent addition device (added fuel supply passage 56 or fuel addition injector 55) due to some abnormality, a start failure of the engine 1 occurs. In the exhaust purification system of this embodiment, When the ECU 5 detects a start failure, the FCV 58 provided upstream of the added fuel supply passage 56 is forcibly closed electrically. For this reason, it is possible to avoid a starting failure in which the common rail pressure cannot maintain a pressure sufficient for starting, and the engine 1 can be operated normally.
[0046]
Further, the ECU 5 of the exhaust purification system of this embodiment detects a starting failure when the engine 1 does not completely explode even when the starter switch has been turned on for a predetermined time. Therefore, even if the air-fuel ratio in the exhaust passage is unstable and the oxygen concentration is at a high level, it is possible to reliably detect a starting failure.
Further, the ECU 5 of the exhaust purification system of this embodiment detects a starting failure when the engine 1 does not completely explode even when the starter switch has been turned ON a predetermined number of times. Therefore, even if the air-fuel ratio in the exhaust passage is unstable and the oxygen concentration is at a high level, it is possible to reliably detect a starting failure.
[0047]
[Second Embodiment]
The FCV 58 shown in the first embodiment cannot be opened from the closed state when the engine 1 starts operation and the discharge pressure of the feed pump 12 increases. Therefore, the opportunity to open the FCV 58 was only when the engine 1 was started.
On the other hand, the FCV 58 that can be opened from the closed state may be used even when the engine 1 starts operation and the discharge pressure of the feed pump 12 increases. That is, the FCV 58 that can be freely opened and closed regardless of the operating state of the feed pump 12 may be used.
[0048]
In this second embodiment, the FCV 58 that can be freely opened and closed is used, and the ECU 5 determines the reducing agent from the operating state of the engine 1 (for example, the engine speed, the amount of fuel injected into the engine 1 by the injector 3, the throttle opening, etc.). It is provided so as to determine the operation unnecessary region of the adding device, and the FCV 58 is forcibly closed when it is determined that the operation state of the engine 1 is in the operation unnecessary region.
Here, when the engine 1 is started (before the complete explosion of the engine 1), it is an operation unnecessary region of the reducing agent addition device in which the fuel addition injector 55 does not open. For this reason, even if a situation where fuel leaks from the reducing agent addition device (added fuel supply passage 56 or fuel addition injector 55) should occur, fuel leakage can be prevented when the engine 1 is started. For this reason, as in the first embodiment, it is possible to avoid a starting failure in which the common rail pressure cannot maintain a pressure sufficient for starting, and the engine 1 can be operated normally.
[0049]
Further, in the second embodiment, it is not necessary to determine whether or not the starting failure as shown in the first embodiment has occurred. For this reason, even if the situation where fuel leaks from the reducing agent addition device should occur, the ON time (cranking time) of the starter switch can be shortened and the number of ON times of the starter switch can be reduced.
[0050]
Further, even when the air-fuel ratio in the exhaust passage is unstable and the oxygen concentration is at a high level when the engine is started, in this embodiment, the reducing agent is added when the engine 1 is started (before the complete explosion of the engine 1). Since the FCV 58 is forcibly closed as an operation unnecessary region of the device, even if a situation where fuel leaks from the reducing agent addition device (added fuel supply passage 56 or fuel addition injector 55) should occur, the fuel leaks at the start of the engine 1 Can be prevented.
[0051]
[Modification]
In the above-described embodiment, a common rail type fuel injection device is shown as an example of the fuel injection device. However, other types of fuel injection devices other than the common rail type, such as a distributed fuel injection device, as well as a pressure accumulation type fuel injection device. You may apply to a fuel-injection apparatus.
In the above embodiment, the example in which the fuel on the low-pressure side of the regulator valve 13 is guided to the reducing agent adding device has been shown. However, any fuel can be used as long as part of the fuel pumped by the fuel injection device is guided to the reducing agent adding device. Alternatively, the fuel at a portion different from the low pressure side of the regulator valve 13 may be provided so as to be guided to the reducing agent addition device.
[0052]
In the above embodiment, the FCV 58 is forcibly closed when the engine 1 is started. However, even if the fuel addition injector 55 detects a fuel leak from the fuel addition injector 55 or the like, the FCV 58 may be forcibly closed. good. By providing in this way, fuel leakage can be prevented by the two valves of the fuel addition injector 55 and the FCV 58, so that the reliability can be improved by this double guarantee.
In the above embodiment, the example in which the present invention is applied to a diesel engine has been shown. However, the present invention can also be applied to other engines such as a gasoline engine. Further, the fuel used as the reducing agent is not limited to light oil, but fuel of the engine such as gasoline, LPG, DME or the like is used.
[Brief description of the drawings]
FIG. 1 is a schematic view of an exhaust purification system.
FIG. 2 is a schematic view of a fuel injection device.
FIG. 3 is a cross-sectional view of a fuel injection pump.
FIG. 4 is a cross-sectional view showing a configuration of a fuel injection pump.
FIG. 5 is a flowchart showing FCV open / close control.
FIG. 6 is an explanatory diagram of a main part of the exhaust purification system.
FIG. 7 is a graph showing the relationship between the rotation speed of the supply pump and the discharge flow rate of the feed pump.
[Explanation of symbols]
1 engine (internal combustion engine)
5 ECU (control device)
51 Exhaust pipe (pipe that forms the exhaust passage)
52 NOx reduction catalyst (reduction purification device)
55 Fuel injector
56 Additive fuel supply passage
58 FCV (fuel cutoff valve)

Claims (4)

A fuel injection device for injecting fuel into the internal combustion engine;
A reduction and purification device installed in the exhaust passage of the internal combustion engine for reducing and purifying exhaust;
A fuel addition injector for adding fuel as a reducing agent into the exhaust passage on the upstream side of the reduction purification device, and an addition fuel supply passage for supplying a part of the fuel pumped by the fuel injection device to the fuel addition injector A reducing agent addition device having
A fuel cutoff valve provided upstream of the additional fuel supply passage and capable of electrically closing the additional fuel supply passage;
A control device for detecting a start failure when starting the internal combustion engine, and forcibly closing the fuel cutoff valve when the start failure is detected;
An exhaust purification system for an internal combustion engine comprising: The exhaust gas purification system for an internal combustion engine according to claim 1,
The exhaust gas purification system for an internal combustion engine, wherein the control device detects a start failure when the internal combustion engine does not completely explode even when the starter switch has been turned on for a predetermined time. The exhaust gas purification system for an internal combustion engine according to claim 1 or 2,
The exhaust gas purification system for an internal combustion engine, wherein the control device detects a start failure when the internal combustion engine does not completely explode even if the starter switch is turned on a predetermined number of times. A fuel injection device for injecting fuel into the internal combustion engine;
A reduction and purification device installed in the exhaust passage of the internal combustion engine for reducing and purifying exhaust;
A fuel addition injector for adding fuel as a reducing agent into the exhaust passage on the upstream side of the reduction purification device, and an addition fuel supply passage for supplying a part of the fuel pumped by the fuel injection device to the fuel addition injector A reducing agent addition device having
A fuel cutoff valve provided upstream of the additional fuel supply passage and capable of electrically closing the additional fuel supply passage;
Means for determining an operation unnecessary region of the reducing agent addition device from an operating state of the internal combustion engine, and forcibly closing the fuel cutoff valve when it is determined that the operating state of the internal combustion engine is in an operation unnecessary region; A control device,
An exhaust purification system for an internal combustion engine comprising:

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