JP2008215322A - Engine system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To effectively use hydrocarbon included in water separated from reformed gas. <P>SOLUTION: This engine system is provided with a fuel reforming part 106 for heating and reforming hydrocarbon fuel and moisture; a condensation part 110 for producing moisture-separated reformed gas by condensing moisture included in reformed gas from the fuel reforming part 106 and removing the moisture as condensed water and for storing the condensed water in a condensed water tank 120; and a condensed water supply part 122 for feeding the condensed water from the condensed water tank 120 to a combustion chamber 10 to burn the condensed water together with the moisture-separated reformed gas. Based on the concentration of hydrocarbon dissolved in the condensed water stored in the condensed water tank 120, supply of the condensed water from the condensed water tank 120 to the combustion chamber 10 is controlled. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an engine system for burning a reformed gas obtained by reforming a hydrocarbon fuel.

  Engine systems have been developed in which moisture is added to hydrocarbon gas, which is heated and reformed before being burned.

  For example, Patent Document 1 discloses a fuel reformer that reforms fuel behind a turbocharger that is driven by exhaust gas, a heat exchanger that generates high-temperature steam, a separator that separates carbon dioxide from exhaust gas, And the engine system provided with the control valve which takes in a part of exhaust gas as EGR gas is disclosed.

  Patent Document 2 discloses a gas engine system in which a hydrogen separator is attached to a fuel reformer, and hydrogen gas generated by the reaction of methane gas and water vapor in the fuel reformer is separated and extracted by the hydrogen separator. Has been.

Japanese Patent Laid-Open No. 2001-152846 JP 2002-221098 A

  By the way, in the conventional engine system, attention is focused on how efficiently the generated reformed gas is combusted or the thermal efficiency of the engine system is improved. The dissolved hydrocarbon was wasted.

  Accordingly, an object of the present invention is to provide an engine system that can effectively use hydrocarbons remaining in water separated from reformed gas.

  The present invention relates to a fuel reforming unit that heats and reforms a hydrocarbon fuel and moisture, and moisture contained in the reformed gas from the fuel reforming unit is condensed and removed as condensed water. And a condensate tank for storing the condensate removed by the condensing unit, and for condensing the condensate from the condensate tank to the combustion chamber in order to burn the condensate with the moisture separation reforming gas. A condensate supply unit for feeding, and controlling the supply of the condensate from the condensate tank to the combustion chamber based on the concentration of hydrocarbons dissolved in the condensate stored in the condensate tank. It is an engine system characterized by.

  Here, the weight of the hydrocarbon fuel and moisture reformed at a temperature lower than a predetermined temperature in the fuel reforming portion relative to the total weight of the hydrocarbon fuel and moisture reformed in the fuel reforming portion. It is preferable to control the supply of condensed water from the condensed water tank to the combustion chamber based on a low temperature reforming ratio expressed as

  For example, when the low temperature reforming ratio is equal to or higher than a predetermined ratio, the moisture separation reformed gas is supplied to the combustion chamber under stoichiometric combustion conditions in which the reformed gas is burned at an ideal air-fuel ratio regardless of engine operating conditions. When condensate is supplied from the condensate tank to the combustion chamber and the low temperature reforming ratio is lower than a predetermined ratio, the stoichiometric combustion condition or the stoichiometric condition is adjusted according to the engine operating conditions. Condensed water is supplied from the condensate tank to the combustion chamber while the moisture separation reformed gas is supplied to the combustion chamber under a lean combustion condition in which the reformed gas is diluted from the metrics combustion condition.

  A water amount sensor that measures the amount of condensed water stored in the condensed water tank, and the amount of condensed water stored in the condensed water tank by the water amount sensor exceeds a predetermined reference water amount; The condensed water may be supplied from the condensed water tank to the combustion chamber.

  Here, the amount of condensed water supplied from the condensed water tank to the combustion chamber may be determined based on the engine speed and output torque. Further, the amount of condensed water supplied from the condensed water tank to the combustion chamber may be feedback controlled so that the time change of the pressure in the combustion chamber falls within a predetermined fluctuation range.

  The condensed water may be supplied from the condensed water tank to the combustion chamber when knocking occurs in the combustion chamber. For example, a knocking detection sensor for detecting knocking generated in the combustion chamber is provided, and condensed water is supplied from the condensed water tank to the combustion chamber when knocking is detected by the knocking detection sensor. The amount of condensed water supplied from the condensed water tank to the combustion chamber may be determined based on the engine speed and output torque.

  In the engine system according to the present invention, the condensed water stored in the upper part of the condensed water tank is supplied to the combustion chamber at a predetermined ratio or more with respect to the total amount of condensed water stored in the condensed water tank. In this case, condensate water is supplied from the condensate tank to the combustion chamber while supplying the moisture separation reformed gas to the combustion chamber under stoichiometric combustion conditions in which the reformed gas is burned at an ideal air-fuel ratio regardless of engine operating conditions. When the condensed water stored in the lower part of the condensed water tank is supplied to the combustion chamber at a predetermined ratio with respect to the total amount of condensed water stored in the condensed water tank, the operating conditions of the engine The moisture separation reformed gas is supplied to the combustion chamber under the lean combustion condition in which the reformed gas is diluted based on the stoichiometric combustion condition or the stoichiometric combustion condition. And while, it is preferable to supply the condensed water to the combustion chamber from the condensed water tank.

  Here, each of the plurality of outlets provided in the condensed water tank is provided with a valve, and by controlling the valve, the condensed water supplied from the condensed water tank to the combustion chamber is extracted from the condensed water tank. The position may be controlled. More specifically, in the condensed water tank supplied from the condensed water tank to the combustion chamber by controlling the valve based on the total amount of condensed water stored in the condensed water tank. The take-out position may be controlled.

  In the engine system according to the present invention, it is preferable that the fuel reforming unit reforms hydrocarbon fuel and moisture using heat of exhaust gas from the combustion chamber. However, the fuel reforming unit may include a heater and reform the hydrocarbon fuel and moisture using the heat of the heat heater.

  The fuel reforming section preferably includes a metal catalyst containing at least one of Rh, Pt, Pd, Cu, Ru, and Ni.

  It is also preferable that the condensed water tank is provided with opening / closing valves at the inlet and the outlet, and the condensed water tank can be sealed by closing the opening / closing valve when the engine system is stopped.

  According to the present invention, it is possible to effectively use hydrocarbons contained in water separated from the reformed gas. Moreover, the amount of hydrocarbon components released to the outside air can be reduced, and the influence on the external environment can be further suppressed.

[First Embodiment]
As shown in FIG. 1, an engine system 100 according to the first embodiment of the present invention includes an engine 102, an exhaust purification unit 104, a fuel reforming unit 106, an evaporator 108, a condensing unit 110, and a reformed gas storage mechanism unit. 112, a reformed gas tank 114, a reformed gas supply unit 116, a condensed water storage mechanism unit 118, a condensed water tank 120, a condensed water supply unit 122, a fuel supply unit 124, a water supply unit 126, and an electronic control unit (ECU) 128. Consists of including.

  The engine 102 includes a combustion chamber 10, an intake pipe 12, an intake valve 14, an exhaust pipe 16, an exhaust valve 18, a throttle valve 20, a spark plug 22, an air flow sensor 24, and a combustion chamber pressure sensor 26. The engine 102 is integrally controlled by the ECU 128. In the combustion chamber 10 of the engine 102, air supplied to the intake pipe 12 using a compressor (not shown) or the like, and the reformed gas injection unit 54 included in the reformed gas supply unit 116 to the intake pipe 12. The water separation reformed gas injected is supplied. Further, depending on conditions, condensed water injected from the condensed water injection unit 62 included in the condensed water supply unit 122 to the intake pipe 12 is supplied to the combustion chamber 10 of the engine 102. The amount of air sent to the intake pipe 12 is measured by the airflow sensor 24, and the amount of air sent to the intake pipe 12 is feedback controlled by controlling the throttle valve 20 by the ECU 128 based on the measured value of the airflow sensor 24. . The air and moisture separation reformed gas, or air, moisture separation reformed gas and condensed water are controlled at a predetermined timing by controlling the opening and closing of the intake valve 14 provided between the intake pipe 12 and the combustion chamber 10. Is fed into the combustion chamber 10. The combustion chamber 10 is provided with a piston, and air and moisture separation reformed gas or air, moisture separation reformed gas and condensed water sent by the spark plug 22 in a state compressed by the piston are combusted. . The piston reciprocates in the combustion chamber 10 by this combustion pressure, thereby rotating the drive shaft. The exhaust gas in the combustion chamber 10 is exhausted to the exhaust purification unit 104 at a predetermined timing by controlling opening and closing of an exhaust valve 18 provided between the combustion chamber 10 and the exhaust pipe 16. Further, the pressure in the combustion chamber 10 is measured by the combustion chamber pressure sensor 26, and the measured value is transmitted to the ECU 128.

  The combustion conditions in the engine 102 are classified into stoichiometric combustion conditions in which the reformed gas is burned at an ideal air-fuel ratio, and lean combustion conditions in which the reformed gas is diluted from the stoichiometric combustion conditions. The ideal air-fuel ratio refers to the weight ratio of the minimum amount of air and fuel that is theoretically necessary for completely burning fuel gas and air. FIG. 2 is a diagram showing the relationship between the rotational speed and output torque of the engine 102 and combustion conditions during normal operation. During normal operation, in a region where the output torque of the engine 102 is low, the engine 102 is operated in a lean combustion condition over the entire rotation speed of the engine 102, and shifts to a stoichiometric combustion condition as the output torque of the engine 102 increases. Further, knocking conditions in which knocking is likely to occur in the engine 102 become a driving condition in which the engine 102 has a low rotation speed under the stoichiometric combustion condition and a part of the driving condition in which the engine 102 has a low rotation speed under the lean combustion condition.

The exhaust purification unit 104 includes an exhaust catalyst 28 and an oxygen sensor 30. Exhaust gas contains harmful substances such as carbon monoxide (CO), hydrocarbons (HC), and nitrogen oxides (NOx). The exhaust purification unit 104 combines carbon monoxide (CO), hydrocarbons (HC), etc. with oxygen by bringing exhaust gas into contact with an exhaust catalyst 28 that combines noble metals such as platinum, palladium, rhodium, etc. It is converted into (CO ₂ ) or water (H ₂ O), and oxygen is separated from nitrogen oxide (NOx) and converted into nitrogen (N ₂ ). The oxygen sensor 30 measures the oxygen concentration in the exhaust gas after passing through the exhaust catalyst 28 and outputs it to the ECU 128. The ECU 128 can monitor the cleanliness of the exhaust gas after processing in the exhaust purification unit 104 based on the oxygen concentration measured by the oxygen sensor 30. The exhaust gas discharged from the exhaust cleaning unit 104 is discharged into the atmosphere via the fuel reforming unit 106 and the evaporator 108.

  The fuel supply unit 124 includes a fuel tank 32, a pump 34, and a flow rate control valve 36. The fuel supply unit 124 is controlled by the ECU 128. Hydrocarbon fuel is stored in the fuel tank 32. The hydrocarbon fuel refers to a fuel containing a hydrocarbon compound such as gasoline, light oil, methane, methanol, and ethanol. The hydrocarbon fuel is sent from the fuel tank 32 to the evaporator 108 by the pump 34. At this time, the amount of hydrocarbon fuel fed into the evaporator 108 per unit time can be controlled by controlling the pump 34 and the flow rate control valve 36 by the ECU 128. The flow rate control valve 36 senses the flow rate per unit time of the passing hydrocarbon fuel and outputs it to the ECU 128.

  The water supply unit 126 includes a water tank 38, a pump 40, and a flow rate control valve 42. The water supply unit 126 is controlled by the ECU 128. Water is stored in the water tank 38. Water is pumped from the water tank 38 to the evaporator 108 by the pump 40. At this time, by controlling the pump 40 and the flow rate control valve 42 by the ECU 128, the amount of water fed into the evaporator 108 per unit time can be controlled. The flow rate control valve 42 senses the flow rate of the passing water per unit time and outputs it to the ECU 128.

  The evaporator 108 forms a heat exchanger, and is supplied from the fuel supply unit 124 and the water supply unit 126 using the heat of the exhaust gas discharged through the exhaust purification unit 104 and the fuel reforming unit 106. Vaporize hydrocarbon fuel and water. The vaporized hydrocarbon fuel and water are supplied to the fuel reforming unit 106.

The fuel reforming unit 106 includes a reforming catalyst 44. The reforming catalyst 44 can be a metal catalyst such as ruthenium (Ru), platinum (Pt), nickel (Ni), for example. The fuel reforming unit 106 forms a heat exchanger, and utilizes the heat of the exhaust gas discharged from the exhaust purification unit 104 to convert the hydrocarbon fuel and water supplied from the evaporator 108 into a reforming catalyst. It is reformed by the catalytic action of 44. The reformed gas generated by the reforming generally contains hydrogen (H ₂ ), methane (CH ₄ ), carbon dioxide (CO ₂ ), carbon monoxide (CO), and water vapor. In addition to these components, high-boiling hydrocarbon components are also included. The reformed gas is sent to the condensing unit 110. Further, a temperature sensor (not shown) may be provided on the reforming catalyst 44, and the temperature of the reforming catalyst 44 may be measured by the temperature sensor and output to the ECU 128.

FIG. 3 is a graph showing the reforming catalyst temperature and the ratio of main components in the reformed gas when gasoline is reformed as an example. As shown in FIG. 3, when gasoline is reformed, the amount of water vapor, methane (CH ₄ ), carbon dioxide (CO ₂ ) decreases as the temperature of the reforming catalyst 44 increases, and hydrogen (H ₂ ). And the amount of carbon monoxide (CO) increases.

  The condensing unit 110 includes a compressor and the like. The condensing unit 110 condenses the reformed gas supplied from the fuel reforming unit 106 to separate moisture from the reformed gas. The reformed gas from which moisture has been removed (hereinafter referred to as moisture separation reformed gas) is accumulated in the reformed gas tank 114 via the reformed gas storage mechanism 112. Further, the condensed water separated from the reformed gas is accumulated in the condensed water tank 120 via the condensed water storage mechanism 118.

  The reformed gas storage mechanism 112 includes a pump 46 and an inlet valve 48. The reformed gas storage mechanism 112 is controlled by the ECU 128. When the water separation reformed gas is supplied from the condensing unit 110, the reformed gas storage mechanism unit 112 opens the inlet valve 48 and sends the water separation reformed gas from the condensing unit 110 to the reformed gas tank 114 by the pump 46. . Further, when the supply of the water separation reformed gas from the condensing unit 110 is stopped, the reformed gas storage mechanism unit 112 closes the inlet valve 48 and stops the pump 46. The reformed gas tank 114 stores the water separation reformed gas that has been sent by the reformed gas storage mechanism 112. The reformed gas supply unit 116 includes an outlet valve 50, a pump 52, and a reformed gas injection unit 54. The reformed gas supply unit 116 is controlled by the ECU 128. When the reformed gas supply command is received from the ECU 128, the reformed gas supply unit 116 opens the outlet valve 50, applies the pressure to the water separation reformed gas stored in the reformed gas tank 114 by the pump 52, and modifies the reformed gas. The moisture separation reformed gas is injected from the quality gas injection unit 54 into the intake pipe 12.

  The condensed water storage mechanism 118 includes an inlet valve. The condensed water storage mechanism 118 is controlled by the ECU 128. When the condensed water is supplied from the condensing unit 110, the condensed water storage mechanism unit 118 opens the inlet valve and sends the condensed water from the condensing unit 110 to the condensed water tank 120. The condensed water storage mechanism 118 closes the inlet valve when the supply of condensed water from the condenser 110 is stopped. The condensed water tank 120 stores the condensed water that has been sent to the condensed water tank 120. A water level sensor 56 is provided in the condensed water tank 120. The amount of condensed water (water level) accumulated in the condensed water tank 120 is measured by the water level sensor 56, and the measurement result is input to the ECU 128. The condensed water supply unit 122 includes an outlet valve 58, a pump 60, and a condensed water injection unit 62. The ECU 128 controls the condensed water supply unit 122 to inject the condensed water stored in the condensed water tank 120 into the intake pipe 12. When the condensate supply command is received from the ECU 128, the condensate supply unit 122 opens the outlet valve 58, applies pressure to the condensate stored in the condensate tank 120 by the pump 60, and the condensate injection unit 62 The condensed water is injected into the intake pipe 12.

  An electronic control unit (ECU) 128 controls the engine system 100 in an integrated manner. The ECU 128 is an electronic circuit including a microcomputer, receives sensing values from the air flow sensor 24, the combustion chamber pressure sensor 26, the oxygen sensor 30, the flow control valves 36 and 42, and the water level sensor 56, and controls each part of the engine system 100. The engine system 100 is controlled by controlling.

  Since the present embodiment is characterized by the control of the supply of water separation reformed gas and condensed water into the intake pipe 12, it will be described below with reference to the flowchart of FIG. In the following description, it is assumed that the engine system 100 has already been started, and the water separation reformed gas and the condensed water are stored in the reformed gas tank 114 and the condensed water tank 120, respectively.

  In step S10, the amount of condensed water in the condensed water tank 120 is measured. The ECU 128 receives the amount of condensed water stored in the condensed water tank 120 from the water level sensor 56.

  In step S12, it is determined whether or not the amount of condensed water stored in the condensed water tank 120 exceeds a predetermined reference amount. If the amount of condensed water is less than or equal to the predetermined reference amount, the process proceeds to step S14, and if it exceeds the predetermined reference amount, the process proceeds to step S16.

  In step S <b> 14, moisture separation reformed gas and air are supplied to the combustion chamber 10 for combustion without supplying condensed water to the combustion chamber 10. The ECU 128 determines the opening degree of the throttle valve 20 and the water separation reformed gas by the outlet valve 50, the pump 52, and the reformed gas injection unit 54 based on the air flow sensor 24, the oxygen sensor 30, and the required output torque and engine speed. 2 is adjusted and supplied to the combustion chamber 10 for combustion while controlling the mixing ratio of the moisture separation reformed gas and air so as to match the combustion conditions shown in FIG. When the process in step S14 ends, the process returns to step S10.

  For example, in the region where the output torque of the engine 102 is low, the mixing ratio of the moisture separation reformed gas and air is controlled so that the lean combustion condition is obtained over the entire rotation speed of the engine 102. As the output torque of the engine 102 increases, the mixing ratio of the moisture separation reformed gas and air is controlled so that the stoichiometric combustion condition is satisfied.

  In step S16, the amount of hydrocarbons dissolved in the condensed water stored in the condensed water tank 120 is estimated. As shown in FIG. 5, the weight ratio of soluble hydrocarbons dissolved in water tends to increase as the temperature of the reforming catalyst 44 decreases.

  Therefore, in this embodiment, the amount of hydrocarbons dissolved in the condensed water is evaluated based on the low temperature reforming ratio. The low temperature reforming ratio refers to carbonization reformed at a temperature lower than a predetermined reference temperature Ta in the fuel reforming unit 106 with respect to the total weight of the hydrocarbon fuel and moisture reformed in the fuel reforming unit 106. The ratio of the weight of hydrogen fuel and moisture. Specifically, (low temperature reforming ratio) = (total amount of hydrocarbon fuel and water supplied to the reforming catalyst at the reference temperature Ta or lower) / (total amount of hydrocarbon fuel and water supplied to the reforming catalyst) Can be defined.

  Here, the reference temperature Ta can be set based on conditions such as the type and mixing ratio of the hydrocarbon fuel to be used, the type of the reforming catalyst 44, the weight of the hydrocarbon fuel and water supplied to the reforming catalyst 44, and the like. preferable. For example, when gasoline is used as the hydrocarbon fuel, the reference temperature Ta is preferably about 500 ° C., and when ethanol is used as the hydrocarbon fuel, the reference temperature Ta is preferably about 400 ° C.

  ECU 128 receives the flow rate of hydrocarbon fuel and the flow rate of water output from flow rate control valve 36 and flow rate control valve 42, respectively, and the temperature of reforming catalyst 44 from a temperature sensor provided in fuel reforming unit 106. Then, the low temperature reforming ratio for each predetermined time is calculated.

  In step S18, control switching determination is performed based on the low temperature reforming ratio. The ECU 128 shifts the process to step S20 if the low temperature reforming ratio is equal to or higher than the predetermined reference weight ratio Ra, and shifts the process to step S22 if not. Here, the reference weight ratio Ra is set based on conditions such as the type and mixing ratio of the hydrocarbon fuel to be used, the type of the reforming catalyst 44, and the weight of the hydrocarbon fuel and water supplied to the reforming catalyst 44. Is preferred. Here, as an example, the reference weight ratio Ra is 50 wt%.

  In step S20, processing is performed when the low-temperature reforming ratio is equal to or greater than a predetermined reference weight ratio Ra. The ECU 128 adjusts the opening ratio of the throttle valve 20 and the injection amount of the water separation reformed gas by the outlet valve 50, the pump 52, and the reformed gas injection unit 54, and sets the mixing ratio of the water separation reformed gas and air to the ideal air. Control is performed so that the stoichiometry condition for combustion at the fuel ratio is satisfied. Further, the ECU 128 controls the condensed water supply unit 122 to inject the condensed water stored in the condensed water tank 120 into the intake pipe 12. That is, while mixing the moisture separation reformed gas and air so as to satisfy the stoichiometry condition regardless of the operating conditions of the engine, the condensed water is further mixed and supplied to the combustion chamber 10 for combustion.

  In step S22, processing is performed when the low-temperature reforming ratio is lower than a predetermined reference weight ratio Ra. The ECU 128 determines the opening degree of the throttle valve 20 and the water separation reformed gas by the outlet valve 50, the pump 52, and the reformed gas injection unit 54 based on the air flow sensor 24, the oxygen sensor 30, and the required output torque and engine speed. Is adjusted to control the mixing ratio of the water separation reformed gas and the air so as to match the combustion conditions shown in FIG. Further, the ECU 128 controls the condensed water supply unit 122 to inject the condensed water stored in the condensed water tank 120 into the intake pipe 12. That is, while the moisture separation reformed gas and air are mixed in accordance with the engine operating conditions, the condensed water is further mixed and supplied to the combustion chamber 10 for combustion.

  For example, in the region where the output torque of the engine 102 is low, while controlling the mixing ratio of the moisture separation reformed gas and air so that the lean combustion condition is achieved over the entire rotation speed of the engine 102, the condensed water is further mixed to the combustion chamber 10 to be burned. Further, as the output torque of the engine 102 increases, while controlling the mixing ratio of the moisture separation reformed gas and air so that the stoichiometric combustion condition is satisfied, the condensed water is further mixed and supplied to the combustion chamber 10 for combustion. .

  The amount of condensed water injection in step S20 and step S22 is preferably set based on the rotational speed of engine 102 and the output torque. For example, as shown in FIG. 6, a map of the condensate injection amount set in advance for the combination of the rotational speed of the engine 102 and the output torque (indicated by a broken-line square in the figure) is stored in the internal memory of the ECU 128. In addition, the condensate injection amount corresponding to the actual engine speed and output torque is obtained from the map of condensate injection amount. In addition, a calculation function of the injection amount of condensed water using the rotation speed and output torque of the engine 102 as variables is determined in advance, and the actual rotation speed and output torque of the engine 102 are introduced into the calculation function to thereby generate the condensed water. The injection amount may be obtained.

  FIG. 7 shows the relationship between the amount of condensed water injected in each cycle and the temperature in the combustion chamber 10, and FIG. 8 shows the relationship between the amount of condensed water injected and the temperature in the combustion chamber 10 at the ignition timing. Since combustion stability has a high correlation with these temperatures, injecting a large amount of condensed water causes a decrease in the stability of the combustion cycle. Therefore, the pressure in the combustion chamber 10 is measured by the combustion chamber pressure sensor 26, and the fluctuation of the work amount for each cycle is calculated based on the pressure, and the fluctuation of the work amount in each cycle becomes equal to or less than a predetermined set reference value. It is also preferable to feedback control the amount of condensed water injection.

[Second Embodiment]
In the second embodiment, an example of controlling the injection of condensed water according to the knocking state of the engine 102 will be described.

  The second embodiment will be described below with reference to the flowchart of FIG. In the following description, it is assumed that the engine system 100 has already been started, and the water separation reformed gas and the condensed water are stored in the reformed gas tank 114 and the condensed water tank 120, respectively. Steps S14 to S22 are the same as those in the first embodiment, and a description thereof will be omitted.

  In step S30, it is determined whether or not the operating state of the engine 102 is in a knocking condition where knocking is likely to occur. The ECU 128 determines whether or not the operating state of the engine 102 is the knock condition in the combustion condition shown in FIG. 2 based on the required output torque and engine speed. If the operating state of engine 102 is the knock condition, the process proceeds to step S14, and if not, the process proceeds to step S16.

(Modification)
In the present embodiment, as shown in FIG. 10, an engine system 200 in which a knocking sensor 70 is provided in the combustion chamber 10 of the engine 102 may be used.

  In this case, in step S30, control is performed based on whether or not the operating state of the engine 102 is in the knocking state by the knocking sensor 70. The ECU 128 receives the output signal from the knocking sensor 70 and shifts the process to step S16 if the engine 102 is in the knocking state, and shifts to step S14 if not.

  In the modification, it is preferable to set the injection amount of the condensed water in step S20 and step S22 based on the output of the knocking sensor 70 of the engine 102. That is, it is also preferable to feedback-control the amount of condensed water injection according to a signal from the knocking sensor 70 so that knocking of the engine 102 does not become extremely severe.

[Third Embodiment]
In the first and second embodiments, only one condensed water supply unit 122 is provided in the condensed water tank 120. However, in the engine system 300 according to the third embodiment, as shown in FIG. An example in which a plurality of condensed water supply units 122a and 122b are provided in the tank 120 will be described.

  The condensed water inlet of the condensed water supply part 122b is provided in the upper part of the condensed water tank 120, and the condensed water inlet of the condensed water supply part 122a is provided below the condensed water inlet of the condensed water supply part 122b. ing.

  In the third embodiment, in step S20 in the flowchart of FIG. 4 or FIG. 9, the ECU 128 controls the opening degree of the throttle valve 20 and the water separation reformed gas generated by the outlet valve 50, the pump 52, and the reformed gas injection unit 54. By adjusting the injection amount, the mixing ratio of the moisture separation reformed gas and air is controlled so as to satisfy the stoichiometry condition for burning at the ideal air-fuel ratio. Further, the ECU 128 controls the condensed water supply unit 122 b to inject condensed water stored in the upper part of the condensed water tank 120 into the intake pipe 12.

  Since the specific gravity of many hydrocarbons is about 0.6 to 0.8 relative to the specific gravity of water, 1.0, the condensed water having a high hydrocarbon concentration is present in the upper portion of the condensed water tank 120 and the hydrocarbon is present in the lower portion. Condensed water with low concentration is stored. That is, in step S20, when mixing the condensed water with the water separation reformed gas and the air so as to satisfy the stoichiometry condition regardless of the engine operating conditions, the condensed water with a high hydrocarbon concentration is given priority. Thus, it is supplied to the combustion chamber 10 and burned.

  On the other hand, in step S22 of FIG. 4 or FIG. 9, the ECU 128 determines the degree of opening of the throttle valve 20, the outlet valve 50, the pump 52, and the air flow sensor 24, the oxygen sensor 30, and the required output torque and engine speed. The amount of moisture separation reformed gas injected by the reformed gas injection unit 54 is adjusted to control the mixing ratio of the moisture separation reformed gas and air so as to match the combustion conditions shown in FIG. Further, the ECU 128 controls the condensed water supply unit 122 a to inject condensed water stored in the lower part of the condensed water tank 120 into the intake pipe 12.

(Modification 1)
In the present embodiment, as shown in FIG. 11, an example in which a plurality of condensed water supply units 122a and 122b that are completely independent is provided in the condensed water tank 120 is shown. However, as shown in FIG. You may make the pump 60 and the condensed water injection part 62 common in supply part 122a, 122b. In this case, the ECU 128 controls the opening and closing of the outlet valves 58a and 58b to change the condensed water take-out position.

(Modification 2)
Moreover, as shown in FIG. 13, you may provide the 3 or more condensed water supply parts 122a, 122b ... 122n (n is an integer greater than or equal to 3). In this case, the level of the condensed water accumulated in the condensed water tank 120 is measured by the water level sensor 56 provided in the condensed water tank 120, and the condensed water supply units 122a, 122b,. It is preferable to assign to the upper part and the lower part.

  For example, as shown in FIG. 13, based on the water level accumulated in the condensed water tank 120, the condensed water supply unit 122 provided with an outlet at a position below half the water level is assigned to the lower part, and the water level The condensate supply unit 122 provided with a takeout port at a position higher than half of the above is assigned to the upper part to control the takeout position of the condensed water supplied into the intake pipe 12.

[Fourth Embodiment]
In the first to third embodiments, the fuel reforming unit 106 and the evaporator 108 are configured to reform the fuel by using the heat of the exhaust gas. However, in the engine system 400 in the fourth embodiment, As shown in FIG. 14, the heaters 72 and 74 are used for the fuel reforming unit 130 and the evaporator 132.

  As described above, by using the heaters 72 and 74 rather than using the heat of the exhaust gas, the temperature controllability in the fuel reforming unit 130 and the evaporator 132 is improved, and the operational stability of the engine system 400 is improved. be able to.

  In the first to fourth embodiments, it is preferable to close all the inlet valves and outlet valves of the condensed water tank 120 when stopping the engine system. Thereby, it is possible to prevent hydrocarbons dissolved in the condensed water accumulated in the condensed water tank 120 from being vaporized and released to the surroundings.

  As described above, the hydrocarbons contained in the water separated from the reformed gas can be used effectively. Moreover, the amount of hydrocarbon components released to the outside air can be reduced, and the influence on the external environment can be further suppressed.

It is a figure which shows the structure of the engine system in the 1st Embodiment of this invention. It is a figure which shows the combustion conditions of an engine system. It is a figure which shows the temperature dependence of the ratio of the product at the time of reforming gasoline. It is a flowchart which shows control of the engine system in the 1st Embodiment of this invention. It is a figure which shows the relationship between the temperature of a reforming catalyst, and the quantity of soluble hydrocarbon. It is a figure which shows the map for calculating | requiring the supply amount of condensed water. It is a figure which shows the relationship between the supply amount of condensed water, and the gas temperature in a combustion chamber. It is a figure which shows the relationship between the supply amount of condensed water, and the gas temperature in the combustion chamber at the time of ignition. It is a flowchart which shows control of the engine system in the 2nd Embodiment of this invention. It is a figure which shows the structure of the engine system in the modification of 2nd Embodiment. It is a figure which shows the structure of the engine system in the 3rd Embodiment of this invention. It is a figure which shows the structure of the engine system in the modification 1 of 3rd Embodiment. It is a figure which shows the structure of the engine system in the modification 2 of 3rd Embodiment. It is a figure which shows the structure of the engine system in 4th Embodiment.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 10 Combustion chamber, 12 Intake pipe, 14 Intake valve, 16 Exhaust pipe, 18 Exhaust valve, 20 Throttle valve, 22 Spark plug, 24 Air flow sensor, 26 Combustion chamber pressure sensor, 28 Exhaust catalyst, 30 Oxygen sensor, 32 Fuel tank, 34 pump, 36 flow control valve, 38 water tank, 40 pump, 42 flow control valve, 44 reforming catalyst, 46 pump, 48 inlet valve, 50 outlet valve, 52 pump, 54 reformed gas injection section, 56 water level sensor, 58 (58a, 58b) outlet valve, 60 pump, 62 condensate injection unit, 70 knocking sensor, 72, 74 heater, 100, 200, 300, 400 engine system, 102 engine, 104 exhaust purification unit, 106 fuel reforming Part, 108 evaporator, 110 condensing part, 112 reformed gas storage mechanism , 114 reformed gas tank, 116 reformed gas supply unit, 118 condensed water storage mechanism unit, 120 condensed water tank, 122 (122a, 122b... 122n) condensed water supply unit, 124 fuel supply unit, 126 water supply unit, 130 Fuel reformer, 132 Evaporator.

Claims (16)

A fuel reforming section for reforming by heating hydrocarbon fuel and moisture;
A condensing unit for condensing moisture contained in the reformed gas from the fuel reforming unit and removing it as condensed water to generate a water separation reformed gas;
A condensed water tank for storing condensed water removed by the condensing unit;
In order to burn the condensed water together with the moisture separation reformed gas, a condensed water supply unit that sends condensed water from the condensed water tank to a combustion chamber, and
An engine system that controls the supply of condensed water from the condensed water tank to the combustion chamber based on the concentration of hydrocarbons dissolved in the condensed water stored in the condensed water tank. The engine system according to claim 1,
The ratio of the weight of hydrocarbon fuel and moisture reformed at a temperature lower than a predetermined temperature in the fuel reforming portion to the total weight of hydrocarbon fuel and moisture reformed in the fuel reforming portion, An engine system that controls supply of condensed water from the condensed water tank to the combustion chamber based on a low temperature reforming ratio expressed as: The engine system according to claim 2,
When the low temperature reforming ratio is equal to or higher than a predetermined ratio, the moisture separation reformed gas is supplied to the combustion chamber under stoichiometric combustion conditions in which the reformed gas is burned at an ideal air-fuel ratio regardless of engine operating conditions. While supplying the condensed water from the condensed water tank to the combustion chamber,
When the low-temperature reforming ratio is lower than a predetermined ratio, the moisture separation reforming is performed under the stoichiometric combustion condition or the lean combustion condition in which the reformed gas is diluted based on the stoichiometric combustion condition in accordance with engine operating conditions. An engine system that supplies condensed water from the condensed water tank to the combustion chamber while supplying gas to the combustion chamber. The engine system according to claim 3,
A water amount sensor for measuring the amount of condensed water stored in the condensed water tank;
An engine system for supplying condensed water from the condensed water tank to the combustion chamber when the amount of condensed water stored in the condensed water tank by the water amount sensor exceeds a predetermined reference water amount. The engine system according to claim 3 or 4,
The amount of condensed water supplied from the condensed water tank to the combustion chamber is determined based on the engine speed and output torque. The engine system according to claim 3 or 4,
The engine system is characterized in that the amount of condensed water supplied from the condensed water tank to the combustion chamber is feedback-controlled so that the temporal change in pressure in the combustion chamber is within a predetermined fluctuation range. The engine system according to claim 3,
An engine system that supplies condensed water from the condensed water tank to the combustion chamber when knocking occurs in the combustion chamber. The engine system according to claim 7,
A knocking detection sensor for detecting knocking generated in the combustion chamber;
An engine system that supplies condensed water from the condensed water tank to the combustion chamber when knocking is detected by the knocking detection sensor. The engine system according to claim 7 or 8,
The amount of condensed water supplied from the condensed water tank to the combustion chamber is determined based on the engine speed and output torque. The engine system according to claim 1,
When supplying the condensed water stored in the upper part of the condensed water tank to the combustion chamber at a predetermined ratio or more with respect to the total amount of condensed water stored in the condensed water tank, regardless of the operating conditions of the engine While supplying the moisture separation reformed gas to the combustion chamber under stoichiometric combustion conditions for combusting the reformed gas at an ideal air-fuel ratio, supplying condensed water from the condensed water tank to the combustion chamber,
When supplying the condensed water stored in the lower part of the condensed water tank to the combustion chamber at a predetermined ratio with respect to the total amount of condensed water stored in the condensed water tank, Supply condensed water from the condensate tank to the combustion chamber while supplying the moisture separation reformed gas to the combustion chamber under stoichiometric combustion conditions or lean combustion conditions in which the reformed gas is diluted according to the stoichiometric combustion conditions An engine system characterized by The engine system according to claim 10, wherein
A valve is provided at each of the plurality of outlets provided in the condensed water tank,
An engine system that controls a take-out position of the condensed water supplied from the condensed water tank to the combustion chamber by controlling the valve. The engine system according to claim 11, wherein
By controlling the valve based on the total amount of condensate stored in the condensate tank, the position of the condensed water supplied from the condensate tank to the combustion chamber is controlled. An engine system characterized by An engine system according to any one of claims 1 to 12,
The engine system, wherein the fuel reforming unit reforms hydrocarbon fuel and moisture using heat of exhaust gas from the combustion chamber. An engine system according to any one of claims 1 to 12,
The engine system, wherein the fuel reforming unit includes a heater and reforms hydrocarbon fuel and moisture using heat of the heat heater. The engine system according to any one of claims 1 to 14,
The engine system, wherein the fuel reforming unit includes a metal catalyst containing at least one of Rh, Pt, Pd, Cu, Ru, and Ni. The engine system according to any one of claims 1 to 15,
The condensate tank is provided with on / off valves at the inlet and outlet,
The engine system is characterized in that the condensed water tank is sealed by closing the on-off valve when the engine system is stopped.

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