Fuel reformer for internal combustion engine

Abstract

To provide a fuel reforming device for an internal combustion engine that effectively suppresses damage of a reforming catalyst due to condensation water generated in the internal combustion engine.SOLUTION: A fuel reforming device for an internal combustion engine includes: a fuel addition device 31 adding reforming fuel to exhaust gas discharged from a combustion chamber 11; and a fuel reformer 35 having a catalyst for decomposing hydrocarbon-based fuel to which the reforming fuel has been added into reformed gas containing hydrogen and carbon monoxide. An exhaust gas recirculation passage 23 for returning exhaust gas discharged from the fuel reformer 35 to intake air includes a cooling device 45. Exhaust gas recirculation passages 231, 232, 233 corresponding to condensation water holding means are disposed at a lower position in the gravity downward direction than a catalyst lower surface standard 100 of the catalyst of the fuel reformer 35 so as to prevent condensation water generated in the exhaust gas recirculation passage 23 from coming into contact with the catalyst. Thus this can prevent damage of a compressor blade in an intake passage due to condensation water and avoid contact of the condensation water with the reforming catalyst so as to prevent damage of the catalyst.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a fuel reformer for an internal combustion engine. [Background technology]

[0002] Conventionally, internal combustion engines are driven by burning a mixture of air and fuel supplied through an intake passage in a combustion chamber. A known technology involves adding fuel to the exhaust gas discharged from the combustion chamber, reforming the exhaust and fuel mixture with a reforming catalyst, and supplying the reformed gas to the intake passage.

[0003] The internal combustion engine of Patent Document 1 includes a reforming means that reforms a mixture of exhaust gas and fuel using a reforming catalyst to produce a reformed gas containing hydrogen, a supercharging means that is provided in the intake passage and pressurizes the air to be supplied to the internal combustion engine, an intake cooling means that is provided in the intake passage and cools the air discharged from the supercharging means, and a gas return passage in the intake passage that returns the reformed gas between the supercharging means and the intake cooling means, and the reformed gas obtained by reforming the mixture of exhaust gas and fuel is returned to the intake passage between the supercharging means and the intake cooling means.

[0004] Patent Document 2 discloses a water drainage device equipped with a condensed water removal passage that discharges air containing condensed water generated by an intercooler in an intake passage downstream of a turbocharger that supercharges the intake air of an internal combustion engine into the intake passage. This condensed water removal passage has a discharge passage cross-sectional area perpendicular to the discharge direction of the air containing condensed water that is narrower than the intake passage cross-sectional area perpendicular to the intake direction of the intake passage, and an orifice narrower than the discharge passage cross-sectional area is provided at the end of the passage. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] JP 2006-37745 A [Patent Document 2] JP 2019-35333 A Summary of the Invention [Problem to be solved by the invention]

[0006] In the fuel reforming system shown in Patent Document 1, when condensed water generated in the cooling device comes into contact with the reforming catalyst, there is a risk that the catalyst may be damaged due to thermal shock, etc., but no configuration for preventing damage to the catalyst is disclosed.

[0007] The internal combustion engine in Patent Document 2 does not disclose a fuel reformer that adds fuel to the exhaust gas, nor does it disclose a water drainage device that discharges condensed water generated in an intercooler that cools the intake air downstream of the turbocharger into the intake passage, but it does not disclose a configuration for preventing damage to the catalyst in the fuel reformer.

[0008] An object of the present invention is to provide a fuel reformer for an internal combustion engine that effectively prevents damage to a reforming catalyst caused by condensed water generated in the internal combustion engine. [Means for solving the problem]

[0009] The fuel reformer for an internal combustion engine of the present invention is an internal combustion engine that extracts external work by burning a mixture of air drawn in from the outside air and fuel in a combustion chamber, and is configured to include a fuel addition device (31) that adds reforming fuel to the exhaust gas discharged from the combustion chamber (11), a fuel reformer (35) having a catalyst that decomposes the hydrocarbon fuel to which the reforming fuel has been added into a reformed gas containing hydrogen and carbon monoxide, an exhaust gas recirculation passage (23) that returns the exhaust gas discharged from the fuel reformer to the intake air, a cooling device (45) installed in the piping of the exhaust gas recirculation passage, and condensed water retention means (33, 231, 232, 233, 234, 2341, 235, 236, 43, 39) that retains condensed water generated in the exhaust gas recirculation passage so that it does not come into contact with the catalyst.

[0010] According to the fuel reformer for an internal combustion engine of the present invention, the condensed water stored in the condensed water storage means is unlikely to come into contact with the catalyst in the portion of the exhaust gas recirculation passage connected to the catalyst outlet, so damage to the catalyst can be effectively suppressed.

[0011] By providing this condensed water retention means, damage to the catalyst can be effectively suppressed regardless of the catalyst shape of the fuel reformer, even in a reforming catalyst (made of a ceramic material) in which heat is exchanged between the exhaust gas and the gas flowing through the exhaust gas recirculation device. Also, if the shape of the exhaust pipe satisfies the requirements, the cooling device can be located below the gravity level of the lower surface of the catalyst of the fuel reformer.

[0012] INDUSTRIAL APPLICABILITY The present invention can improve the reliability of a catalyst in a fuel reforming system for an internal combustion engine having a catalyst for reforming a hydrocarbon fuel in an exhaust gas recirculation passage of the internal combustion engine. According to the fuel reformer for an internal combustion engine of the present invention, in a fuel reforming system equipped with a device for recirculating exhaust gas from an internal combustion engine, the fuel reformer has a configuration for suppressing contact between the catalyst and condensed water, thereby making it possible to suppress damage to the catalyst.

[0013] When a cooling device such as an EGR cooler is installed above the lower surface level of the reforming catalyst of the fuel reformer due to gravity, condensed water generated in the cooling device is stored in a condensed water holding means, thereby preventing damage to the catalyst due to condensed water. [Brief description of the drawings]

[0014] [Figure 1] 1 is a schematic diagram showing the configuration of a fuel reforming system according to a first embodiment. [Diagram 2] FIG. 11 is a schematic diagram showing a partial configuration of a fuel reforming system according to a second embodiment. [Diagram 3] FIG. 2 is an explanatory diagram illustrating condensed water generated in an EGR cooler. [Figure 4] FIG. 11 is a schematic diagram showing a partial configuration of a fuel reforming system according to a third embodiment. [Diagram 5] FIG. 11 is a schematic diagram showing a partial configuration of a fuel reforming system according to a fourth embodiment. [Figure 6] FIG. 11 is a schematic diagram showing a partial configuration of a fuel reforming system according to a fifth embodiment. [Figure 7]FIG. 13 is a schematic diagram showing a partial configuration of a fuel reforming system according to a sixth embodiment. [Figure 8] FIG. 13 is a schematic diagram showing the configuration of a fuel reforming system according to a seventh embodiment. [Figure 9] 13 is a flowchart illustrating a condensed water discharge process according to the seventh embodiment. [Figure 10] FIG. 13 is a schematic diagram showing the configuration of a fuel reforming system according to an eighth embodiment. [Figure 11] FIG. 13 is a schematic diagram showing the configuration of a fuel reforming system according to a ninth embodiment. [Figure 12] FIG. 23 is a schematic diagram showing the configuration of a fuel reforming system according to a tenth embodiment. [Figure 13] FIG. 23 is a schematic diagram showing a partial configuration of a fuel reforming system according to an eleventh embodiment. [Figure 14] 23 is a flowchart illustrating a condensed water discharge process according to an eleventh embodiment. [Figure 15] FIG. 23 is a schematic diagram showing a partial configuration of a fuel reforming system according to a twelfth embodiment. [Figure 16] 16 is a schematic cross-sectional view showing the configuration of a portion XVI in FIG. 15. [Figure 17] A graph showing the NOx and SOx content before and after the catalyst. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0015] Hereinafter, a fuel reformer for an internal combustion engine according to an embodiment of the present invention will be described with reference to the drawings. Note that, in a plurality of embodiments, substantially the same components are given the same reference numerals, and the description thereof will be omitted.

[0016] (First embodiment) A first embodiment of the present invention will be described with reference to FIG. The first embodiment is shown in Fig. 1. As shown in Fig. 1, a fuel reforming system 1 adds fuel to exhaust gas discharged from an internal combustion engine (hereinafter referred to as "engine") 10 of a vehicle (not shown), and supplies the engine 10 with reformed fuel reformed by a reforming catalyst.

[0017] The vehicle includes an engine 10, an intake passage 21, an exhaust passage 22, an exhaust gas recirculation passage 23, a turbocharger 25, an intercooler 28, a fuel reformer 35, an EGR valve 41, an EGR cooler 45 which corresponds to a cooling device, and the like.

[0018] The engine 10 is a multi-cylinder engine, for example, four cylinders. FIG. 1 shows a schematic cross section of one cylinder. The injector 12 injects and supplies gasoline as fuel to a combustion chamber 11 of the engine 10. That is, the engine 10 of this embodiment is a gasoline engine. The engine 10 burns a mixture of intake air supplied from an intake passage 21 and fuel injected from the injector 12 in the combustion chamber 11, and causes a piston 13 to reciprocate by the energy generated during combustion. The reciprocating motion of the piston 13 is converted into the rotational motion of a crankshaft (not shown). The engine 10 of this embodiment is a spark ignition type, and the mixture is ignited by generating an electric discharge between the electrodes of the spark plug 15.

[0019] An intake valve 17 is provided at the connection between the combustion chamber 11 and the intake passage 21, and an exhaust valve 18 is provided at the connection between the combustion chamber 11 and the exhaust passage 22. The intake valve 17 and the exhaust valve 18 are driven to open and close by a valve drive mechanism (not shown).

[0020] The intake passage 21 is provided so that one end is open to the atmosphere and the other end is connected to the engine 10. The intake passage 21 guides the intake air that flows in via the air cleaner 19 to the engine 10. The exhaust passage 22 is provided so that one end is connected to the engine 10 and the other end is open to the atmosphere. The exhaust passage 22 guides exhaust gas generated by the combustion of fuel in the combustion chamber of the engine 10 from the engine 10 to the atmosphere. The exhaust recirculation passage 23 is provided so that one end is connected to the exhaust passage 22 and the other end is connected to the intake passage 21. The exhaust recirculation passage 23 recirculates the exhaust gas flowing in the exhaust passage 22 to the intake passage 21.

[0021] Hereinafter, in the intake passage 21, the side open to the atmosphere is referred to as the upstream side, and the engine 10 side is referred to as the downstream side. In the exhaust passage 22, the engine 10 side is referred to as the upstream side, and the side open to the atmosphere is referred to as the downstream side. In the exhaust recirculation passage 23, the exhaust passage 22 side is referred to as the upstream side, and the intake passage 21 side is referred to as the downstream side.

[0022] The supercharger 25 has a compressor 251 and a turbine 252, which are connected by a shaft 253 and rotate together. The compressor 251 is provided in the intake passage 21, and the turbine 252 is provided in the exhaust passage 22. The turbine 252 rotates by the kinetic energy of the exhaust gas flowing through the exhaust passage 22, which rotates the compressor 251, compressing the intake air in the intake passage 21 and supplying it to the engine 10. This enables supercharging.

[0023] The intercooler 28 is provided downstream of the compressor 251 in the intake passage 21, and cools the intake air whose temperature has increased as a result of being compressed by the compressor 251. This improves the fuel efficiency and output of the engine 10. A throttle valve 29 is provided downstream of the intercooler 28 in the intake passage 21. By adjusting the opening degree of the throttle valve 29, the intake air volume, which is the amount of intake air flowing through the intake passage 21, can be controlled.

[0024] A bypass passage 271 that communicates between the upstream side and downstream side of the turbine 252 is provided in the exhaust passage 22. A wastegate valve 272 is provided in the bypass passage 271. By adjusting the opening degree of the wastegate valve 272, the amount of exhaust gas flowing into the turbine 252 side can be adjusted.

[0025] A fuel reformer 35 is provided in the exhaust passage 22 downstream of the turbine 252. A fuel addition passage 225 branching off from the exhaust passage 22 is connected to the inlet side of the fuel reformer 35, and an upstream end of the exhaust recirculation passage 23 is connected to the outlet side. A fuel addition device 31 is provided in the fuel addition passage 225. The fuel addition device 31 adds fuel for reforming to the fuel addition passage 225. The fuel for reforming may be the same as that supplied to the engine 10, or may be different.

[0026] The fuel reformer 35 has a reforming catalyst and reforms the fuel that has flowed in, generating a reformed gas mainly composed of hydrogen and carbon monoxide. The recirculated gas containing the reformed gas is supplied to the engine 10 via the exhaust gas recirculation passage 23.

[0027] The EGR valve 41 is provided in the exhaust recirculation passage 23. The flow rate of recirculated gas flowing through the exhaust recirculation passage 23 can be adjusted by adjusting the opening degree of the EGR valve 41. A flow rate sensor 78 for detecting the flow rate of the recirculated gas is provided downstream of the EGR valve 41. The EGR cooler 45 is provided upstream of the EGR valve 41 in the exhaust recirculation passage 23, and cools the recirculated gas. In the drawings, the recirculated gas is referred to as "EGR" where appropriate.

[0028] In the first embodiment, a condensed water removal device is provided in the fuel reforming system 1 of the engine. With respect to the exhaust gas recirculation passage 23, an exhaust gas recirculation passage 231 extends in a direction below gravity lower than a catalyst lower surface level 100 where the catalyst of the fuel reformer 35 is located, and an inlet 451 and an outlet 452 of an EGR cooler 45 corresponding to a cooling device are provided at a position below the catalyst lower surface level 100 on the extension of the exhaust gas recirculation passage 231 in a direction below gravity lower than the catalyst lower surface level 100. An exhaust gas recirculation passage 232 connected to the inlet 451 of the EGR cooler 45 and an exhaust gas recirculation passage 233 connected to the outlet 452 are located at a lower position below the catalyst lower surface level 100 in the direction below gravity. As a result, the exhaust gas recirculation passages 231, 232, and 233 corresponding to the condensed water holding means are disposed at a lower position below the catalyst lower surface level 100 of the catalyst of the fuel reformer 35 in the direction below gravity.

[0029] Therefore, condensed water generated when the engine is started is retained in the exhaust gas recirculation passages 231, 232, 233 so that it does not come into contact with the catalyst of the fuel reformer 35. This prevents the condensed water from damaging the compressor blades in the intake passage, prevents the condensed water from coming into contact with the reforming catalyst, and suppresses the release of toxic and flammable gases into the exhaust gas or atmosphere. Second embodiment

[0030] In the second embodiment, as shown in FIG. 2, the condensed water removal device has an exhaust gas recirculation passage between an EGR cooler 45 corresponding to a cooling device and the fuel reformer 35 with a heat exchanger, so that the condensed water does not come into contact with the catalyst of the fuel reformer 35. The volume V of the exhaust gas recirculation passage 234 corresponding to the condensed water holding means surrounded by a dashed line 90 in the downward direction of gravity from the catalyst lower surface level 100 of the fuel reformer 35 is the piping volume of the exhaust gas recirculation passage in the downward direction of gravity from the lowermost surface of the catalyst of the fuel reformer 35, and has a piping structure having a volume larger than the volume W of condensed water generated in the EGR cooler 45. Other configurations of the second embodiment are similar to those shown in FIG.

[0031] FIG. 3 shows the amount of condensed water generated in the EGR cooler per second and the temperature T of the hottest point of the EGR cooler over time. The amount of condensed water dm / dc generated in the EGR cooler per second is expressed as the amount of water vapor S (g / sec) in the EGR minus the amount of saturated steam D (g / sec). According to the graph in FIG. 3, if the engine is started and then driven continuously, the temperature T of the EGR cooler gradually increases after the engine is started. It can be seen that after a certain time has passed, the increase in the amount of accumulated condensed water stops.

[0032] According to this embodiment, the volume V of the exhaust gas recirculation passage 234 is larger than the volume W of the condensed water generated in the EGR cooler 45. Fig. 3 shows an example, where V>M (=accumulated amount of condensed water M). The piping volume V in the exhaust gas recirculation passage located in the direction downward from the bottom surface of the catalyst of the fuel reformer 35 is larger than the volume W of condensed water generated in the EGR cooler. Third embodiment

[0033] In the third embodiment, the fuel reformer 36 without a heat exchanger is placed horizontally, as shown in Fig. 4. With respect to the exhaust gas recirculation passage 234 between the EGR cooler 45 and the fuel reformer 36 without a heat exchanger, the EGR cooler 45 and the horizontally placed fuel reformer 36 are located above the level 100 of the catalyst lower surface of the fuel reformer 36 under the force of gravity. The volume V of the exhaust gas recirculation passage 234, which corresponds to the condensed water holding means surrounded by the dashed line 90 below the level 100 of the catalyst under the force of gravity, is the piping volume of the exhaust gas recirculation passage 234 from the lowest surface of the catalyst downward by gravity, and has a volume larger than the volume W of the condensed water generated in the EGR cooler 45. Other configurations of the third embodiment are similar to those shown in FIG. (Fourth embodiment)

[0034] In the fourth embodiment, as shown in FIG. 5, the exhaust gas recirculation passage 234 connecting the EGR cooler 45 and the fuel reformer 35 with a heat exchanger is arranged so that the EGR cooler 45 and the fuel reformer 35 are located gravitationally above the catalyst underside level 100 of the fuel reformer 35. In the exhaust gas recirculation passage 234 connecting the EGR cooler 45 and the fuel reformer 35 with a heat exchanger, an enlarged volume portion 2341 for holding condensed water 4 is formed in the exhaust gas recirculation passage 234 in the direction downward of gravity from the catalyst lower surface level 100. The volume V of the exhaust gas recirculation passage 234 surrounded by the dashed line 90 in the direction downward of gravity from the catalyst lower surface level 100 is the piping volume of the exhaust gas recirculation passage in the direction downward of gravity from the bottommost surface of the catalyst, and has a volume larger than the volume W of condensed water generated in the EGR cooler 45. Fifth embodiment

[0035] 6, an exhaust gas recirculation passage 235 connects an EGR cooler 45 and a fuel reformer 35 with a heat exchanger. The EGR cooler 45 and the exhaust gas recirculation passage 235, which corresponds to a condensed water holding means, are located below the level 100 of the catalyst lower surface of the fuel reformer 36 in the direction of gravity. The piping volume V of the exhaust gas recirculation passage 235 surrounded by a dashed line 90 below the level 100 of the catalyst lower surface of the fuel reformer 35 in the direction of gravity is larger than the volume W of condensed water generated in the EGR cooler 45. Sixth embodiment

[0036] 7, in the sixth embodiment, an exhaust gas recirculation passage 235 corresponding to a condensed water holding means connects an EGR cooler 45 and a fuel reformer 36 without a heat exchanger. The EGR cooler 45 and the exhaust gas recirculation passage 235 are located below gravity below a catalyst lower surface level 100 of the horizontally placed fuel reformer 36 without a heat exchanger. The piping volume V of the exhaust gas recirculation passage 235 surrounded by a broken line 90 below gravity below the catalyst lower surface level 100 of the fuel reformer 36 is larger than the volume W of condensed water generated in the EGR cooler 45. Seventh embodiment

[0037] In the seventh embodiment, as shown in FIG. 8, an exhaust temperature sensor 46 is provided in the exhaust passage 22, and an exhaust purification catalyst 37 is provided on the exhaust discharge side of the exhaust temperature sensor 46. The exhaust EGR cooler 45 and the fuel reformer with a heat exchanger are connected by an exhaust gas recirculation passage 236, which corresponds to the condensed water retaining means. The exhaust gas recirculation passage 236 is located below the catalyst lower surface level 100 of the fuel reformer in the direction of gravity.

[0038] A condensed water reservoir chamber 33 corresponding to a condensed water holding means formed in the middle of the exhaust gas recirculation passage 236 in the downward direction of gravity of the EGR cooler 45 is formed. The piping volume V of the exhaust gas recirculation passage 236 in the direction below gravity below the catalyst lower surface level 100 is larger than the volume W of condensed water generated in the EGR cooler 45 .

[0039] Between the exhaust temperature sensor 46 in the exhaust passage 22 and the exhaust purification catalyst 37, one end 381 of a condensed water discharge pipe 38 is connected to the condensed water reservoir chamber 33, and the other end 382 of the condensed water discharge pipe 38 is connected. A condensed water retention weir 39, which corresponds to a condensed water retention means for retaining condensed water, is formed inside the exhaust pipe 22 on the exhaust discharge side of the other end 382 of the condensed water discharge pipe 38. The condensed water retention weir 39 is a blocking structure that prevents discharged condensed water from entering the exhaust purification catalyst 37. This prevents damage to the exhaust purification catalyst.

[0040] The condensed water discharge pipe 38 is provided with a condensed water discharge valve 40 for discharging the condensed water. The ECU 50 receives a catalyst temperature signal corresponding to the exhaust temperature signal detected by the exhaust temperature sensor 46, and a signal from the water detection sensor 42 that detects the presence or absence of condensed water in the condensed water reservoir chamber 33. The ECU 50 determines the presence or absence of the exhaust temperature signal (catalyst temperature signal) and the water detection signal, and controls the opening and closing of the condensed water drain valve 40 in accordance with the determination signal.

[0041] FIG. 9 shows an example of control of the condensed water drain valve 40. It is determined whether the engine is stopped (step S101), and when the engine stop state is detected, the catalyst temperature of the fuel reformer 35 is calculated from the detection signal of the exhaust temperature sensor 46 (step S102). When it is determined that the catalyst temperature is higher than the catalyst activation temperature (step S103), the condensed water drain valve 40 is opened (step S104), and the presence or absence of condensed water is detected (step S105). When it is determined that condensed water is present (step S106), if the catalyst temperature is higher than the catalyst activation temperature, the condensed water drain valve 40 is opened (step S104). If no condensed water is present, the condensed water drain valve 40 is closed (step S107).

[0042] After the engine is stopped, condensed water generated in the exhaust gas recirculation device is discharged into the exhaust pipe 22 in front of the exhaust gas purification catalyst 37. By discharging the steam before the exhaust purification catalyst 37, the steam of the condensed water (including fuel and acidic substances) and the EGR gas (H2, CO) discharged at the same time are rendered harmless by the exhaust purification catalyst 37 in an active state after the engine is stopped and released into the atmosphere. Eighth embodiment

[0043] In the eighth embodiment, as shown in FIG. 10, an exhaust temperature sensor 46 is provided in the exhaust passage 22, and an exhaust purification catalyst 37 is provided on the exhaust discharge side of the exhaust temperature sensor 46. The exhaust EGR cooler 45 and the fuel reformer with a heat exchanger are connected by an exhaust gas recirculation passage 236, which corresponds to the condensed water retaining means. The exhaust gas recirculation passage 236 is located below the catalyst lower surface level 100 of the fuel reformer in the direction of gravity.

[0044] A condensed water reservoir chamber 33 corresponding to the condensed water holding means is formed midway in the exhaust gas recirculation passage 236, below the gravity of the EGR cooler 45. The piping volume V of the exhaust gas recirculation passage 236 in the direction below gravity below the catalyst lower surface level 100 is larger than the volume W of condensed water generated in the EGR cooler 45 . One end 381 of a condensed water discharge pipe 38 is connected to the condensed water reservoir chamber 33 , and the other end 382 of the condensed water discharge pipe 38 is connected to a portion of the exhaust passage 22 between the exhaust temperature sensor 46 and the exhaust purification catalyst 37 .

[0045] A condensed water retaining recess 43 corresponding to a condensed water retaining means for retaining condensed water is formed inside the exhaust pipe 22 on the exhaust discharge side of the other end 382 of the condensed water drain pipe 38. The condensed water drain pipe 38 is provided with a condensed water drain valve 40 for draining condensed water. Ninth embodiment

[0046] As shown in FIG. 11, the ninth embodiment has a basic configuration similar to that of the seventh embodiment shown in FIG. The other end 383 of the condensed water discharge pipe 38 joins with the exhaust passage 22, and the joining point opens into the exhaust passage 22 in the opposite direction of the condensed water retention weir 39, which corresponds to the condensed water retention means, so that the gas flowing through the condensed water discharge pipe 38 flows in the opposite direction. Tenth embodiment

[0047] In the tenth embodiment, as shown in FIG. 12, an exhaust gas recirculation passage 231 extends downward in the direction of gravity below the catalyst of the fuel reformer 35, and an ultrasonic vibrator 47 corresponding to the atomization means for atomizing condensed water is provided on the extension of the exhaust gas recirculation passage 231 at a position below the catalyst lower surface level 100 in the direction of gravity. When the ultrasonic vibrator 47 is operated, it applies vibrations to the condensed water, atomizing the condensed water 4 accumulated in the exhaust gas recirculation passage.

[0048] As a result, by atomizing the condensed water 4 from the exhaust gas recirculation passage 23, which corresponds to the piping section that holds the condensed water, it is possible to discharge the condensed water into the intake port together with the exhaust gas without re-condensing it in the EGR cooler 45 and without placing stress on intake parts such as the turbocharger. The other configurations are similar to those of the first and second embodiments shown in FIGS. Eleventh embodiment

[0049] In the eleventh embodiment, as shown in FIG. 13, an enlarged volume section 2341 for holding condensed water is formed in the exhaust gas recirculation passage 234 that connects the EGR cooler 45 and the fuel reformer 35 with a heat exchanger, below the catalyst lower surface level 100 and in the direction downward of gravity.

[0050] A water sensor 51 that detects the presence or absence of condensed water is provided in the expanded volume portion 2341. A signal from the water sensor 51 is input to the ECU 50, and when water is detected, the ECU 50 commands the ultrasonic vibrator 47 to operate, vibrating the expanded volume portion 2341 and atomizing the condensed water, thereby making it possible to discharge the condensed water into the intake port together with the exhaust gas without re-condensing it in the EGR cooler 45 and without putting stress on intake parts such as a turbocharger. The other configurations of the eleventh embodiment are similar to those of the fourth embodiment shown in FIG.

[0051] FIG. 14 shows an example of control of an ultrasonic vibrator that corresponds to the atomization means. It is determined whether the engine is stopped (step S201), and when it is detected that the engine is stopped, the catalyst temperature of the fuel reformer 35 is calculated from the detection signal of the exhaust temperature sensor 46 (step S202), and when it is determined that the catalyst temperature is higher than the catalyst activation temperature (step S203), it determines whether or not condensed water is present (step S204). When the ECU 50 receives a signal from the water sensor 51 and determines that condensed water is present (step S205), it activates the ultrasonic vibrator 47, which corresponds to the atomization means (step S206). When it is determined that no condensed water is present, the operation of the ultrasonic vibrator 47 is stopped (step S207). Twelfth embodiment

[0052] The twelfth embodiment, as shown in Figs. 15 and 16, is an embodiment example in which corrosion resistant means is provided at the portions that come into contact with condensed water. 16 is a schematic diagram of the pipe 24 of the exhaust gas recirculation passage 234. FIG 17 shows an example of a graph of the amounts of NOx and SOx contained in the exhaust gas before and after passing through the catalyst of the fuel reformer 35.

[0053] A surface treatment layer 53 corresponding to the corrosion-resistant means is formed on the inner wall of the base material of the pipe 24 constituting the exhaust gas recirculation passage 234 for storing condensed water. Since there is a high possibility that NOx and carboxylic acids will be decomposed by the catalyst when fuel reforming is assumed, the surface treatment layer 53 is preferably a plating layer made of chromium or nickel, which has high corrosion resistance to sulfuric acid (SOx) and hydrochloric acid, which are not purified by the catalyst. Other configurations of this embodiment are similar to those of the second embodiment shown in Fig. 2. Furthermore, other basic configurations of the other embodiments are similar to those of the first embodiment.

[0054] In the present invention, a piping structure is provided for holding condensed water generated in a cooling device or the like when starting the engine, so that the condensed water does not come into contact with the catalyst of the fuel reformer or the catalyst of the exhaust purification catalyst. After the engine is stopped, the condensed water generated in the exhaust gas recirculation device can be discharged through a passage to the exhaust pipe to the exhaust pipe before the exhaust purification catalyst. By discharging the condensed water before the catalyst, the steam of the condensed water containing fuel or acidic substances and the EGR gas of H2 and CO2 generated at the same time are rendered harmless by the exhaust purification catalyst in an active state after the engine is stopped and released into the atmosphere. Moreover, by providing a shielding structure that prevents discharged condensed water from entering the exhaust purification catalyst, damage to the exhaust purification catalyst can also be prevented.

[0055] In the fuel reformer for an engine according to the present invention, the condensate retaining means described in the means for solving the problem is a pipe (23, 231, 232, 233) between the fuel reformer and the cooling device, and can be located below the gravity level (100) of the catalyst underside of the fuel reformer. Since the condensed water accumulates below the catalyst lower surface level 100 in the direction of gravity, it is possible to prevent the condensed water from coming into contact with the catalyst of the fuel reformer. The part of the exhaust gas recirculation passage that connects to the catalyst outlet is located at a position lower than the lower surface of the catalyst of the fuel reformer, so that the condensed water is less likely to come into contact with the catalyst.

[0056] In the fuel reformer for an engine according to the present invention, the condensed water holding means can set the volume V of the space inside the pipes (23, 231, 232, 233) to be larger than the volume W of condensed water generated in the cooling device. For example, the shape of the pipes forming the space inside the pipes is manufactured to have this setting. This makes it possible to hold the condensed water even when the volume W of condensed water generated in the cooling device reaches its maximum, and to avoid or suppress contact with the catalyst.

[0057] In the fuel reformer of the engine according to the present invention, the volume W of condensed water generated in the cooling device can be calculated using the maximum temperature Tmax in the cooling device, the saturated vapor pressure ew, the saturated vapor amount D, and the accumulated condensed water amount M. In the fuel reformer for an engine according to the present invention, the cooling device may be arranged to be located below the level of a lower surface of the catalyst of the fuel reformer in the direction of gravity.

[0058] The engine fuel reformer of the present invention may include means (50) for detecting engine stoppage, a condensed water discharge pipe (38) for discharging condensed water from the condensed water holding means into an exhaust pipe (22), the exhaust pipe having a structure (39) for holding the discharged condensed water, a control valve (40) for opening and closing an internal passage of the condensed water discharge pipe, a water sensor (42) for detecting the presence or absence of water in the condensed water holding means, an exhaust purification catalyst (37) provided on the exhaust outlet side of the structure, catalyst temperature detection means (36) for detecting the temperature of the exhaust purification catalyst, and control means (50) for controlling the opening and closing of the control valve based on a detection signal of the water sensor and a catalyst temperature signal of the exhaust purification catalyst.

[0059] The fuel reformer for an engine according to the present invention may be configured to include atomization means (47) for atomizing the condensed water stored in the condensed water storage means. In this case, a place for storing the condensed water is provided, and an atomization device is installed in that place, so that the condensed water can be efficiently discharged. In this case, by atomizing the condensed water from a condensed water holding means equivalent to a pipe or the like for holding the condensed water, in an exhaust cooling device such as an EGR cooler, the condensed water can be discharged into the intake port together with the exhaust gas without re-condensing and without placing stress on intake parts such as a turbocharger.

[0060] The engine fuel reformer of the present invention may be configured to include a water sensor (51) for detecting the presence or absence of water in the condensed water holding means (2341), a determination means (50) for determining the presence or absence of water based on a detection signal of the water sensor, and a control means (50) for operating the atomization means when the determination means determines the presence of water as a result.

[0061] In the fuel reformer for an engine according to the present invention, the condensed water in the condensed water holding means and the inner wall of the pipe in the exhaust gas recirculation passage which comes into contact with the condensed water may be provided with corrosion-resistant means (53).

[0062] In the fuel reformer for an engine according to the present invention, the corrosion-resistant means may be a means for adhering one or more transition metals selected from the group consisting of chromium, nickel, copper, zinc, silver, platinum, gold and rhodium to the metal surface. In the case of a fuel reformer, since there is a high possibility that NOx and carboxylic acids will be decomposed by the catalyst, a suitable corrosion-resistant means is surface treatment with chromium, nickel, etc., which have high corrosion resistance to SOx and hydrochloric acid that are not purified by the catalyst.

[0063] In the fuel reformer for an engine according to the present invention, the fuel reformer comprises a reforming catalyst that decomposes fuel, and a substrate that supports the catalyst, and the substrate may be made of Si-based ceramic.

[0064] As described above, the present invention is not limited to the above-described embodiment, and can be embodied in various forms without departing from the spirit and scope of the present invention. [Explanation of symbols]

[0065] 1 Fuel reforming system, 10 engines, 21 Intake passage, 22 Exhaust passage (exhaust pipe), 23, 231, 232, 233, 234, 235, 236 Exhaust recirculation passage (condensed water retention means), 24 Piping, 25 Supercharger, 28 Intercooler, 31 Fuel addition device, 33 Condensate reservoir (condensate storage means), 35 Fuel reformer, 36 Fuel reformer, 37 Exhaust gas purification catalyst, 38 Condensate drain piping, 39 Condensate retention weir (structure, condensate retention means); 40 Condensate drain valve (control valve), 41 EGR valve, 42, 51 Water sensor (means for detecting the presence or absence of condensed water), 43 Condensate retention recess, 45 EGR cooler (cooling device), 46 exhaust temperature sensor (catalyst temperature detection means), 47 Ultrasonic vibrator (atomization means), 50 ECU (control means), 53 Surface treatment layer (corrosion resistance means), 100 Catalyst bottom level, 2341 Volume expansion section (means for retaining condensate).

Claims

1. In an internal combustion engine, a mixture of air and fuel drawn from the outside is combusted in a combustion chamber to produce external work, a fuel addition device (31) that adds reforming fuel to the exhaust gas discharged from the combustion chamber (11); A fuel reformer (35) having a catalyst for decomposing a hydrocarbon fuel to which a reforming fuel has been added into a reformed gas containing hydrogen and carbon monoxide; an exhaust gas recirculation passage (23) for returning the exhaust gas discharged from the fuel reformer to the intake air; A cooling device (45) installed in the piping of the exhaust gas recirculation passage; and a condensed water retaining means (33, 231, 232, 233, 234, 2341, 235, 236, 43, 39) for retaining condensed water generated in the exhaust gas recirculation passage so as not to come into contact with the catalyst.

2. 2. A fuel reformer for an internal combustion engine according to claim 1, wherein said condensed water retaining means is a pipe (23, 231, 232, 233) between said fuel reformer and said cooling device, and is located in a direction below gravity below a lower surface level (100) of the catalyst of said fuel reformer.

3. 3. A fuel reforming device for an internal combustion engine according to claim 2, wherein the condensed water holding means has an internal space volume V of the piping (23, 231, 232, 233) larger than a volume W of condensed water generated in the cooling device.

4. 4. A fuel reforming device for an internal combustion engine according to claim 3, wherein the condensed water volume W is calculated using a saturated vapor pressure ew, a saturated vapor amount D, and an integrated condensed water amount M, using a maximum temperature T in the cooling device.

5. 2. A fuel reformer for an internal combustion engine according to claim 1, wherein said cooling device is positioned below the level of a lower surface of said catalyst of said fuel reformer in a direction below gravity.

6. 6. A fuel reforming device for an internal combustion engine according to claim 1, comprising: means (50) for detecting the stop of an internal combustion engine; a condensed water discharge pipe (38) for discharging condensed water from the condensed water holding means to an exhaust pipe (22); the exhaust pipe having a structure (39) for holding the discharged condensed water; a control valve (40) for opening and closing an internal passage of the condensed water discharge pipe; a water sensor (42) for detecting the presence or absence of water in the condensed water holding means; an exhaust purification catalyst (37) provided on the exhaust outlet side of the structure; catalyst temperature detection means (36) for detecting the temperature of the exhaust purification catalyst; and control means (50) for controlling the opening and closing of the control valve based on a detection signal of the water sensor and a catalyst temperature signal of the exhaust purification catalyst.

7. 6. A fuel reforming device for an internal combustion engine according to claim 1, further comprising atomizing means (47) for atomizing the condensed water stored in the condensed water storage means.

8. 8. A fuel reforming device for an internal combustion engine as described in claim 7, comprising a water sensor (51) for detecting the presence or absence of water in the condensed water holding means (2341), a discrimination means (50) for determining whether water is present based on a detection signal from the water sensor, and a control means (50) for operating the atomization means when the discrimination means determines the presence of water as a result.

9. 2. A fuel reforming device for an internal combustion engine according to claim 1, wherein an anti-corrosion means (53) is provided on inner walls of pipes which come into contact with the condensed water in said condensed water holding means and the condensed water in said exhaust gas recirculation passage.

10. 10. A fuel reformer for an internal combustion engine according to claim 9, wherein said corrosion-resistant means is a means for adhering one or more transition metals selected from the group consisting of chromium, nickel, copper, zinc, silver, platinum, gold and rhodium to a metal surface.

11. 2. A fuel reforming device for an internal combustion engine according to claim 1, wherein said fuel reformer comprises a reforming catalyst for decomposing fuel, and a substrate for supporting said reforming catalyst, said substrate being made of a silicon-based ceramic.

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