JP6394364B2 - Fuel reformer for internal combustion engine - Google Patents

Description

  The present invention relates to a fuel reforming apparatus for an internal combustion engine provided with a fuel reforming catalyst for reforming the fuel of the internal combustion engine.

As a technique for improving the fuel consumption by reforming the fuel of the internal combustion engine, for example, there is one described in Patent Document 1 (Japanese Patent Laid-Open No. 2007-285157). This is a modification of the reforming fuel injection valve for injecting reforming fuel and the reforming fuel in the middle of the EGR passage for returning a part of the exhaust gas from the exhaust passage of the internal combustion engine to the intake passage as EGR gas. And a fuel reforming catalyst to be improved. The reforming fuel injected by the reforming fuel injection valve and the moisture (water vapor) in the EGR gas are reformed by the fuel reforming catalyst to generate hydrogen (H ₂ ) or carbon monoxide (CO). Thus, the reforming fuel is reformed to generate a reformed gas having high combustibility, and the reformed gas is supplied to the intake passage of the internal combustion engine. Further, in Patent Document 1, the fuel reforming catalyst is controlled by controlling the injection amount of the reforming fuel so as to be within the control region set based on the temperature and the reforming gas amount of the fuel reforming catalyst. The reforming performance is improved by suppressing deterioration of the resin.

JP 2007-285157 A

  By the way, the pressure of the EGR gas pulsates due to the influence of the exhaust pressure pulsation of the internal combustion engine, and the EGR gas flow rate fluctuates due to the pressure pulsation of the EGR gas. However, in the technique of the above-mentioned Patent Document 1, since the influence of the pressure pulsation of the EGR gas is not taken into consideration at all, the influence of the change in the EGR gas flow rate due to the pressure pulsation of the EGR gas causes the reforming fuel. There is a possibility that the mixing ratio of the EGR gas (water vapor) and the reforming fuel will fluctuate for each injection. When the mixing ratio of the EGR gas and the reforming fuel changes, the S / C (ratio of water vapor to carbon) of the gas supplied to the fuel reforming catalyst fluctuates, and the deterioration suppressing effect and reforming of the fuel reforming catalyst Performance may be degraded. For example, when the S / C is small (that is, carbon is increased with respect to water vapor), the amount of carbon deposited on the fuel reforming catalyst is increased, and the amount of carbon deposited on the fuel reforming catalyst is increased. The degree of deterioration of the reforming catalyst tends to increase and the reforming performance tends to decrease.

  Accordingly, the problem to be solved by the present invention is to provide a fuel reformer for an internal combustion engine that can suppress fluctuations in the mixing ratio of EGR gas and reforming fuel for each injection of reforming fuel. It is in.

In order to solve the above problems, the invention according to claim 1 is directed to a main fuel injection means (21) for injecting main fuel supplied to the internal combustion engine (11), and an exhaust passage (23) of the internal combustion engine (11). An EGR passage (32) that recirculates a part of the exhaust gas as EGR gas to the intake passage (12), reforming fuel injection means (35) that injects reforming fuel into the EGR passage (32), A fuel reformer for an internal combustion engine, comprising a fuel reforming catalyst (36) disposed in the EGR passage (32) and reforming the reforming fuel injected by the reforming fuel injection means (35). When a predetermined reforming control execution condition is satisfied, reforming fuel is injected by the reforming fuel injection means (35), and the reforming fuel is reformed by the fuel reforming catalyst (36), and reformed gas Reforming control means (37) for executing reforming control for generating reforming fuel and injection of reforming fuel Pressure information acquisition means (37, 38) for detecting or estimating the pressure of the EGR gas passing through the position or information correlated therewith (hereinafter collectively referred to as “pressure information of the EGR gas in the vicinity of the injection position”); The reforming control means (37) sets the injection condition of the reforming fuel based on the pressure information of the EGR gas near the injection position , and the reforming control means (37) is the EGR gas near the injection position. The reforming fuel injection timing is set in synchronization with the pulsation of the pressure information .

  In this way, the reforming fuel injection conditions (for example, the injection timing and the injection amount) are appropriately set in response to the change in the EGR gas flow rate in the vicinity of the injection position in accordance with the pressure of the EGR gas in the vicinity of the injection position. Thus, the mixing ratio of EGR gas and reforming fuel for each injection of reforming fuel can be made substantially constant. As a result, even if the EGR gas flow rate fluctuates due to the pressure pulsation of the EGR gas, the fluctuation (variation) in the mixing ratio of the EGR gas and the reforming fuel for each injection of the reforming fuel can be suppressed. As a result, the fluctuation (variation) in the S / C (ratio of water vapor and carbon) of the gas supplied to the fuel reforming catalyst can be suppressed, and the reforming performance can be improved by suppressing the deterioration of the fuel reforming catalyst. Can be made.

FIG. 1 is a diagram showing a schematic configuration of an engine control system in Embodiment 1 of the present invention. FIG. 2 is a time chart illustrating a method for setting the reforming fuel injection timing according to the first embodiment. FIG. 3 is a flowchart showing the flow of processing of the reforming control routine of the first embodiment. FIG. 4 is a time chart illustrating a method for setting the injection amount of the reforming fuel according to the second embodiment. FIG. 5 is a flowchart showing the flow of processing of the reforming control routine of the second embodiment.

  Hereinafter, some embodiments embodying the mode for carrying out the present invention will be described.

A first embodiment of the present invention will be described with reference to FIGS.
First, a schematic configuration of the entire engine control system will be described with reference to FIG.
An air cleaner 13 is provided at the most upstream portion of the intake pipe 12 (intake passage) of the engine 11 that is an internal combustion engine, and an air flow meter 14 that detects the intake air amount is provided downstream of the air cleaner 13. A throttle valve 16 whose opening is adjusted by a motor 15 and a throttle opening sensor 17 for detecting the opening (throttle opening) of the throttle valve 16 are provided on the downstream side of the air flow meter 14.

  Further, a surge tank 18 is provided on the downstream side of the throttle valve 16, and an intake pipe pressure sensor 19 for detecting the intake pipe pressure is provided in the surge tank 18. The surge tank 18 is provided with an intake manifold 20 for introducing air into each cylinder of the engine 11, and main fuel is injected into the intake port at or near the intake port connected to the intake manifold 20 of each cylinder. A main fuel injection valve 21 (main fuel injection means) is attached. An ignition plug 22 is attached to the cylinder head of the engine 11 for each cylinder, and the air-fuel mixture in each cylinder is ignited by spark discharge of the ignition plug 22 of each cylinder.

  On the other hand, the exhaust pipe 23 (exhaust passage) of the engine 11 is provided with a catalyst 24 such as a three-way catalyst for purifying exhaust gas, and the exhaust gas air-fuel ratio or rich gas is respectively provided upstream and downstream of the catalyst 24. / Exhaust gas sensors 25 and 26 (air-fuel ratio sensor, oxygen sensor, etc.) for detecting lean etc. are provided.

  A cooling water temperature sensor 27 that detects the cooling water temperature and a knock sensor 28 that detects knocking are attached to the cylinder block of the engine 11. A crank angle sensor 30 that outputs a pulse signal every time the crankshaft 29 rotates by a predetermined crank angle is attached to the outer peripheral side of the crankshaft 29. Based on the output signal of the crank angle sensor 30, the crank angle and engine The rotation speed is detected.

  The engine 11 is equipped with an EGR device 31 that recirculates a part of the exhaust gas from the exhaust pipe 23 to the intake pipe 12 as EGR gas. The EGR device 31 has an EGR pipe 32 (EGR passage) connected between the upstream side (or downstream side) of the catalyst 24 in the exhaust pipe 23 and the downstream side of the throttle valve 16 in the intake pipe 12. The EGR pipe 32 is provided with an EGR cooler 33 for cooling the EGR gas and an EGR valve 34 for adjusting the flow rate of the EGR gas. By opening the EGR valve 34, the EGR gas is recirculated from the exhaust pipe 23 to the intake pipe 12 through the EGR pipe 32.

A reforming fuel injection valve 35 (reforming fuel injection means) for injecting reforming fuel into the EGR pipe 32 is provided on the upstream side of the EGR cooler 33 in the EGR pipe 32. The main fuel injection valve 21 and the reforming fuel injection valve 35 are supplied with fuel from a common fuel tank (not shown). Further, a fuel reforming catalyst 36 for reforming the reforming fuel injected by the reforming fuel injection valve 35 is disposed on the downstream side of the reforming fuel injection valve 35 in the EGR pipe 32. . The fuel reforming catalyst 36 is configured to exchange heat with the exhaust gas flowing in the exhaust pipe 23, and reforms the reforming fuel and moisture (water vapor) in the EGR gas by using the heat of the exhaust gas. By reacting to generate hydrogen (H ₂ ) and carbon monoxide (CO), the reforming fuel is reformed to generate a reformed gas having high combustibility.

  Further, in the vicinity of the reforming fuel injection valve 35 in the EGR pipe 32, the pressure of the EGR gas passing through the reforming fuel injection position (hereinafter referred to as “the pressure of the EGR gas near the injection position”) is detected. A pressure sensor 38 (pressure information acquisition means) is provided.

  Outputs of the various sensors described above are input to an electronic control unit (hereinafter referred to as “ECU”) 37. The ECU 37 is mainly composed of a microcomputer, and executes various engine control programs stored in a built-in ROM (storage medium), so that the fuel injection amount and the ignition timing are determined according to the engine operating state. The throttle opening (intake air amount) and the like are controlled.

  At that time, the ECU 37 calculates a target EGR rate (target value of the EGR rate) based on the engine operating state when a predetermined EGR control execution condition is satisfied, and an EGR gas flow rate (target value) corresponding to the target EGR rate. EGR control for controlling the opening degree of the EGR valve 34 so as to realize (EGR gas flow rate) is executed. Here, the EGR rate is a ratio of the in-cylinder inflow EGR gas flow rate to the in-cylinder inflow total gas flow rate (= in-cylinder inflow EGR gas flow rate / in-cylinder inflow total gas flow rate).

  In the first embodiment, the ECU 37 executes a reforming control routine shown in FIG. 3 to be described later, thereby executing reforming control when a predetermined reforming control execution condition is satisfied. In this reforming control, reforming fuel is injected into the EGR pipe 32 by the reforming fuel injection valve 35, and the reforming fuel and moisture (water vapor) in the EGR gas are reformed by the fuel reforming catalyst 36. The reforming fuel is reformed to generate a reformed gas having high combustibility by generating hydrogen and carbon monoxide through a quality reaction, and the reformed gas is supplied to the intake pipe 12.

Incidentally, the EGR gas pressure pulsates due to the pulsation of the exhaust pressure of the engine 11 and the EGR gas flow rate fluctuates due to the pressure pulsation of the EGR gas (see FIGS. 2 and 4). Therefore, as shown by the broken line in FIG. 2, the injection timing of the reforming fuel is set without considering the influence of the pressure pulsation of the EGR gas, or as shown by the broken line in FIG. If the injection amount of the reforming fuel is set without considering the effect of the pressure pulsation of the EGR gas, the EGR gas flow is affected by the change in the EGR gas flow rate due to the pressure pulsation of the EGR gas. There is a possibility that the mixing ratio of (steam) and reforming fuel will fluctuate. When the mixing ratio of the EGR gas and the reforming fuel varies, the S / C (ratio of water vapor to carbon) of the gas supplied to the fuel reforming catalyst 36 varies, and the deterioration suppressing effect of the fuel reforming catalyst 36 There is a possibility that the reforming performance deteriorates. For example, when the S / C is small (that is, the amount of carbon is increased with respect to water vapor), the amount of carbon deposited on the fuel reforming catalyst 36 increases, and the amount of carbon deposited on the fuel reforming catalyst 36 increases. The deterioration degree of the fuel reforming catalyst 36 tends to increase and the reforming performance tends to decrease.
Therefore, the ECU 37 sets the injection condition of the reforming fuel based on the pressure of the EGR gas in the vicinity of the injection position (the pressure of the EGR gas passing through the injection position of the reforming fuel).

  In the first embodiment, the reforming control routine of FIG. 3 to be described later is executed by the ECU 37, so that the reforming fuel is synchronized with the pressure pulsation of the EGR gas in the vicinity of the injection position as shown by the solid line in FIG. Set the injection timing. As a result, the EGR gas pressure (EGR gas flow rate) near the injection position at each injection timing of the reforming fuel is made substantially constant, and the mixing ratio of the EGR gas and the reforming fuel for each injection of the reforming fuel. Can be made substantially constant, and the S / C of the gas supplied to the fuel reforming catalyst 36 can be made almost constant.

  At this time, in the first embodiment, the injection timing of the reforming fuel is set at the timing when the pressure of the EGR gas near the injection position becomes the peak value (for example, the pressure of the EGR gas near the injection position becomes the peak value). The injection timing of the reforming fuel is set so that the timing of the injection period of the reforming fuel straddles the timing).

Hereinafter, the processing content of the reforming control routine of FIG. 3 executed by the ECU 37 in the first embodiment will be described.
The reforming control routine shown in FIG. 3 is repeatedly executed at a predetermined cycle during the power-on period of the ECU 37, and plays a role as reforming control means in the claims.

When this routine is started, first, at step 101, it is determined whether or not the reforming control execution condition is satisfied. For example, the execution condition of EGR control is satisfied (that is, the EGR control is being executed). That is, the determination is made based on whether all the conditions such as the temperature of the fuel reforming catalyst 36 being equal to or higher than the activation temperature are satisfied.
If it is determined in step 101 that the reforming control execution condition is not satisfied, this routine is terminated without executing the processing from step 102 onward.

  On the other hand, if it is determined in step 101 that the reforming control execution condition is satisfied, the process proceeds to step 102 where the temperature of the fuel reforming catalyst 36, the degree of deterioration of the fuel reforming catalyst 36, and the target EGR rate. The target S / C is set (calculated) using a map or the like based on at least one of the above.

  Thereafter, the process proceeds to step 103, where the pressure sensor 38 detects the pressure of the EGR gas near the injection position, and detects the pressure pulsation (pressure waveform) of the EGR gas near the injection position. At this time, if the distance from the pressure sensor 38 to the reforming fuel injection position is relatively long, a map that takes into account the EGR gas transfer delay or a model (formula etc.) that simulates the behavior of the EGR gas is used. Based on the output of the pressure sensor 38, the pressure of the EGR gas near the injection position is calculated.

  It should be noted that EGR gas near the injection position based on the operation conditions using a map that defines the relationship between the operation conditions (for example, engine speed, engine load, target EGR rate, etc.) and the pressure of EGR gas near the injection position. The pressure pulsation of the EGR gas near the injection position may be estimated (calculated). In this case, the pressure sensor 38 may be omitted, and the ECU 37 serves as pressure information acquisition means in the scope of the claims.

  Thereafter, the process proceeds to step 104, and the EGR gas flow rate is calculated based on the target EGR rate and the like using a model (formula etc.) simulating the behavior of the EGR gas. Alternatively, the EGR gas flow rate is calculated by a map or the like based on the output of the pressure sensor 38. In this case, an average EGR gas flow rate in the vicinity of the injection position may be calculated, or an EGR gas flow rate in the vicinity of the injection position at the injection timing (for example, a timing at which the pressure of the EGR gas in the vicinity of the injection position becomes a peak value). May be calculated.

  Thereafter, the process proceeds to step 105, where the amount of water vapor in the EGR gas is calculated by a map or the like based on the EGR gas flow rate and operating conditions (for example, fuel type, air-fuel ratio, etc.), and the target S / C is revised. The injection quantity of quality fuel is calculated.

  Thereafter, the routine proceeds to step 106, where the injection timing of the reforming fuel is set at the EGR gas pressure peak timing (the timing at which the pressure of the EGR gas near the injection position reaches the peak value). Specifically, the reforming fuel injection timing is set such that the reforming fuel injection period straddles the EGR gas pressure peak timing (see FIG. 2). Alternatively, the reforming fuel injection timing may be set so that the reforming fuel injection start timing becomes the EGR gas pressure peak timing. Further, the reforming fuel injection timing may be set so that the reforming fuel injection end timing becomes the EGR gas pressure peak timing.

  Thereafter, the routine proceeds to step 107, where reforming fuel is injected by the reforming fuel injection valve 35 at the reforming fuel injection timing, and reforming control is executed. In this reforming control, reforming fuel is injected into the EGR pipe 32 by the reforming fuel injection valve 35, and the reforming fuel and moisture (water vapor) in the EGR gas are reformed by the fuel reforming catalyst 36. The reforming fuel is reformed to produce reformed gas with high combustibility by producing hydrogen and carbon monoxide through a quality reaction.

  In the first embodiment described above, the reforming fuel injection timing is set so as to be synchronized with the pressure pulsation of the EGR gas in the vicinity of the injection position. In this way, the EGR gas pressure (EGR gas flow rate) near the injection position at each injection timing of the reforming fuel is made substantially constant, and the EGR gas and the reforming fuel for each injection of the reforming fuel. The mixing ratio of can be made almost constant. As a result, even if the EGR gas flow rate fluctuates due to the pressure pulsation of the EGR gas, the fluctuation (variation) in the mixing ratio of the EGR gas and the reforming fuel for each injection of the reforming fuel can be suppressed. As a result, the S / C fluctuation (variation) of the gas supplied to the fuel reforming catalyst 36 can be suppressed, and the reforming performance can be improved by suppressing the deterioration of the fuel reforming catalyst 36.

  In the first embodiment, the reforming fuel injection timing is set to the EGR gas pressure peak timing (the timing at which the pressure of the EGR gas near the injection position reaches the peak value). Since the EGR gas pressure peak timing can be detected with relatively high accuracy, if the reforming fuel injection timing is set to the EGR gas pressure peak timing, the reforming fuel injection timing is set with high accuracy. be able to.

  In the first embodiment, the injection timing of the reforming fuel is set at the EGR gas pressure peak timing. However, the present invention is not limited to this. For example, the EGR gas pressure bottom timing (the EGR gas near the injection position) The injection timing of the reforming fuel may be set at the timing when the pressure reaches the bottom value. Specifically, the reforming fuel injection timing is set so that the reforming fuel injection period straddles the EGR gas pressure bottom timing. Alternatively, the reforming fuel injection timing may be set so that the reforming fuel injection start timing becomes the EGR gas pressure bottom timing. Further, the reforming fuel injection timing may be set so that the reforming fuel injection end timing becomes the EGR gas pressure bottom timing. Since the EGR gas pressure bottom timing can also be detected with relatively high accuracy, even when the reforming fuel injection timing is set at the EGR gas pressure bottom timing, the reforming fuel injection timing is set with high accuracy. be able to.

  Further, the timing is not limited to the EGR gas pressure peak timing or the EGR gas pressure bottom timing, but at a predetermined timing synchronized with the pressure pulsation of the EGR gas near the injection position (for example, the EGR gas pressure near the injection position has a peak value and a bottom value). The reforming fuel injection timing may be set at an intermediate value or the like.

  In the first embodiment, the reforming fuel injection timing is set so as to be synchronized with the pressure pulsation of the EGR gas near the injection position. The reforming fuel injection timing may be set so as to be synchronized with the pulsation of the flow rate (the flow rate of the EGR gas passing through the reforming fuel injection position).

  In this case, a flow rate sensor (pressure information acquisition means) for detecting the flow rate of EGR gas near the injection position is provided in the vicinity of the reforming fuel injection valve 35, and the flow rate of EGR gas near the injection position is detected by this flow rate sensor. The flow rate pulsation (flow rate waveform) of the EGR gas near the injection position may be detected. Alternatively, the flow rate pulsation of the EGR gas near the injection position may be estimated by calculating (calculating) the flow rate of the EGR gas near the injection position based on the output of the pressure sensor 38 or the operating condition.

  Then, the injection timing of the reforming fuel is set at the EGR gas flow rate peak timing (timing at which the EGR gas flow rate near the injection position reaches the peak value). Specifically, the reforming fuel injection timing is set so that the reforming fuel injection period straddles the EGR gas flow rate peak timing (see FIG. 2). Alternatively, the reforming fuel injection timing may be set so that the reforming fuel injection start timing becomes the EGR gas flow rate peak timing. Further, the reforming fuel injection timing may be set so that the reforming fuel injection end timing becomes the EGR gas flow rate peak timing.

  Alternatively, the reforming fuel injection timing may be set at the EGR gas flow bottom timing (timing at which the EGR gas flow rate near the injection position becomes the bottom value). Specifically, the reforming fuel injection timing is set so that the reforming fuel injection period straddles the EGR gas flow bottom timing. Alternatively, the reforming fuel injection timing may be set so that the reforming fuel injection start timing becomes the EGR gas flow bottom timing. Further, the reforming fuel injection timing may be set so that the reforming fuel injection end timing becomes the EGR gas flow rate bottom timing.

  The EGR gas flow rate peak timing and the EGR gas flow rate bottom timing are not limited to a predetermined timing synchronized with the EGR gas flow rate pulsation near the injection position (for example, the EGR gas flow rate near the injection position has a peak value and a bottom value). The reforming fuel injection timing may be set at an intermediate value or the like.

  Next, Embodiment 2 of the present invention will be described with reference to FIGS. However, description of substantially the same parts as those in the first embodiment will be omitted or simplified, and different parts from the first embodiment will be mainly described.

  In the second embodiment, the reforming control routine of FIG. 5 described later is executed by the ECU 37, and as shown by the solid line in FIG. 4, the pressure of the EGR gas near the injection position at the injection timing of the reforming fuel is determined. To set the injection amount of reforming fuel. Thus, even if the pressure of the EGR gas (EGR gas flow rate) near the injection position changes at each injection timing of the reforming fuel, the reforming fuel is changed according to the pressure of the EGR gas (EGR gas flow rate). By changing the injection amount, the mixing ratio of the EGR gas and the reforming fuel for each injection of the reforming fuel can be made substantially constant, and the S / C of the gas supplied to the fuel reforming catalyst 36 can be reduced. It can be made almost constant.

At this time, in the second embodiment, the injection amount of the reforming fuel is increased as the pressure of the EGR gas near the injection position at the reforming fuel injection timing is higher.
Hereinafter, the processing content of the reforming control routine of FIG. 5 executed by the ECU 37 in the second embodiment will be described.

  In the reforming control routine shown in FIG. 5, first, in step 201, it is determined whether or not the reforming control execution condition is satisfied by the same method as in step 101 of FIG. If it is determined, the process proceeds to step 202, where the target S / C is set (calculated) in the same manner as in step 102 of FIG.

  Thereafter, the process proceeds to step 203, and after detecting or estimating the pressure pulsation of the EGR gas in the vicinity of the injection position by the same method as in step 103 of FIG. 3, the process proceeds to step 204, and each injection timing of the reforming fuel is set to a predetermined crank angle. Set at a cycle or a predetermined time cycle.

  Thereafter, the routine proceeds to step 205, where the EGR gas flow rate near the injection position at each injection timing of the reforming fuel is mapped or EGR gas based on the pressure of the EGR gas near the injection position at each injection timing of the reforming fuel. This is calculated using a model (such as a mathematical formula) that simulates the behavior of

Thereafter, the routine proceeds to step 206, where the amount of water vapor in the EGR gas is mapped on the basis of the EGR gas flow rate near the injection position and the operating conditions (for example, fuel type, air-fuel ratio, etc.) for each injection timing of the reforming fuel. The injection amount of the reformed fuel at each injection timing is calculated by calculating the injection amount of the reformed fuel so that the target S / C is obtained. At this time, the injection amount of the reforming fuel is increased as the pressure of the EGR gas near the injection position at the reforming fuel injection timing is higher (that is, the EGR gas flow rate is higher).
Thereafter, the routine proceeds to step 207, where reforming fuel is injected by the reforming fuel injection valve 35 at the reforming fuel injection timing, and reforming control is executed.

  In the second embodiment described above, the injection amount of the reforming fuel is set according to the pressure of the EGR gas near the injection position at the reforming fuel injection timing. In this way, even if the pressure of the EGR gas (EGR gas flow rate) near the injection position changes at each injection timing of the reforming fuel, the reforming is performed according to the pressure of the EGR gas (EGR gas flow rate). The mixing ratio of the EGR gas and the reforming fuel for each injection of the reforming fuel can be made substantially constant by changing the injection amount of the reforming fuel. Thereby, substantially the same effect as the first embodiment can be obtained.

  In the second embodiment, the injection amount of the reforming fuel is increased as the pressure of the EGR gas near the injection position at the injection timing of the reforming fuel is higher. In this way, the higher the EGR gas pressure near the injection position at the reforming fuel injection timing, the higher the EGR gas flow rate near the injection position, and the higher the EGR gas flow rate near the injection position. As a result, the mixing ratio of the EGR gas and the reforming fuel can be made substantially constant.

  In the second embodiment, the EGR gas flow rate near the injection position at each injection timing is calculated based on the pressure of the EGR gas near the injection position at each injection timing of the reforming fuel, and the EGR gas flow rate is calculated as the EGR gas flow rate. Based on this, by calculating the injection amount at each injection timing, the injection amount is set according to the pressure of the EGR gas near the injection position at each injection timing. However, the present invention is not limited to this. For example, after uniformly calculating the injection amount at each injection timing based on the average EGR gas flow rate, the EGR gas in the vicinity of the injection position is changed at each injection timing of the reforming fuel. By correcting the injection amount in accordance with the pressure, the injection amount may be set in accordance with the pressure of the EGR gas near the injection position at each injection timing.

  In the second embodiment, the injection amount of the reforming fuel is set according to the pressure of the EGR gas near the injection position at the injection timing of the reforming fuel. However, the present invention is not limited to this. The reforming fuel injection amount may be set in accordance with the flow rate of EGR gas near the injection position at the fuel injection timing.

  In this case, a flow rate sensor (pressure information acquisition means) for detecting the flow rate of the EGR gas near the injection position is provided in the vicinity of the reforming fuel injection valve 35, and the EGR gas near the injection position at each injection timing by this flow rate sensor. May be detected, and the injection amount at each injection timing may be calculated based on these EGR gas flow rates (detected values). Alternatively, the flow rate of EGR gas in the vicinity of the injection position at each injection timing is estimated (calculated) based on operating conditions and the like, and the injection amount at each injection timing is calculated based on these EGR gas flow rates (estimated values). You may do it.

  Also, by combining the first embodiment and the second embodiment, the injection timing of the reforming fuel is set so as to synchronize with the pressure pulsation of the EGR gas near the injection position, and further, at the injection timing of the reforming fuel The amount of reforming fuel injection may be set according to the pressure of EGR gas near the injection position. For example, the injection timing of the reforming fuel is set at the EGR gas pressure peak timing and the EGR gas pressure bottom timing, and the injection amount at the EGR gas pressure peak timing according to the pressure of the EGR gas near the injection position at the EGR gas pressure peak timing And the injection amount at the EGR gas pressure bottom timing is set according to the pressure of the EGR gas near the injection position at the EGR gas pressure bottom timing.

  Alternatively, the reforming fuel injection timing is set so as to be synchronized with the flow rate pulsation of the EGR gas in the vicinity of the injection position, and further modified according to the EGR gas flow rate in the vicinity of the injection position at the reforming fuel injection timing. The injection amount of the quality fuel may be set. For example, the injection timing of the reforming fuel is set at the EGR gas flow rate peak timing and the EGR gas flow rate bottom timing, and the injection amount at the EGR gas flow rate peak timing according to the EGR gas flow rate near the injection position at the EGR gas flow rate peak timing And the injection amount at the EGR gas flow bottom timing is set according to the flow rate of the EGR gas near the injection position at the EGR gas flow bottom timing.

  In addition, the present invention is not limited to the intake port injection type engine as shown in FIG. 1, but includes an in-cylinder injection type engine, and both an intake port injection fuel injection valve and an in-cylinder injection fuel injection valve. It can also be applied to dual-injection engines.

  DESCRIPTION OF SYMBOLS 11 ... Engine (internal combustion engine), 12 ... Intake pipe (intake passage), 21 ... Main fuel injection valve (main fuel injection means), 23 ... Exhaust pipe (exhaust passage), 24 ... Catalyst, 32 ... EGR piping (EGR passage) ), 35 ... reforming fuel injection valve (reforming fuel injection means), 36 ... fuel reforming catalyst, 37 ... ECU (reforming control means, pressure information acquisition means), 38 ... pressure sensor (pressure information acquisition means) )

Claims (5)

A main fuel injection means (21) for injecting main fuel supplied to the internal combustion engine (11), and an intake passage (12) using EGR gas as a part of exhaust gas from the exhaust passage (23) of the internal combustion engine (11). An EGR passage (32) for recirculation, reforming fuel injection means (35) for injecting reforming fuel into the EGR passage (32), and the reforming fuel disposed in the EGR passage (32). A fuel reformer for an internal combustion engine, comprising a fuel reforming catalyst (36) for reforming the reforming fuel injected by the fuel injection means (35).
When a predetermined reforming control execution condition is satisfied, the reforming fuel is injected by the reforming fuel injection means (35), and the reforming fuel is reformed by the fuel reforming catalyst (36). Reforming control means (37) for executing reforming control to generate reformed gas
Pressure information acquisition for detecting or estimating the pressure of EGR gas passing through the injection position of the reforming fuel or information correlated therewith (hereinafter collectively referred to as “pressure information of EGR gas near the injection position”) Means (37, 38),
The reforming control means (37) sets injection conditions for the reforming fuel based on pressure information of EGR gas near the injection position ,
The reforming control means (37) sets an injection timing of the reforming fuel so as to synchronize with a pulsation of pressure information of EGR gas near the injection position. .   The fuel reformer for an internal combustion engine according to claim 1, wherein the pressure information acquisition means (37, 38) detects or estimates pressure or flow rate as pressure information of EGR gas in the vicinity of the injection position. The reforming control unit (37), according to claim 1, characterized in that the pressure information of the EGR gas in the vicinity of the ejection position to set the injection timing of fuel for the reforming in timing at which the peak value or the bottom value or 3. A fuel reformer for an internal combustion engine according to 2 . The reforming control means (37) sets the injection amount of the reforming fuel according to pressure information of EGR gas in the vicinity of the injection position at the injection timing of the reforming fuel. The fuel reformer for an internal combustion engine according to any one of 1 to 3 . The reforming control means (37) increases the injection amount of the reforming fuel as the pressure information of the EGR gas near the injection position at the injection timing of the reforming fuel becomes higher. The internal combustion engine fuel reformer according to claim 4 .

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