JP2010106774A - Reformed gas engine system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To effectively treat a condensate while improving thermal efficiency. <P>SOLUTION: A reformed gas engine system S1 is equipped with a condensate supply device 46 for supplying the condensate stored in a condenser 32 to an upstream side with respect to a ternary catalyst 72 in an exhaust passage 68, and an ECU 56. In the ECU 56, when an amount of the condensate stored in the condenser 32 is within a predetermined amount range, a reformed gas lean combustion mode is selected, a gas injection valve 40 and a throttle valve 70 are controlled such that an engine 44 is operated in a lean condition, and the condensate supply device 46 is controlled such that the condensate stored in the condenser 32 is supplied to the upstream side with respect to the ternary catalyst 72 in the exhaust passage 68. By such configuration, since the engine 44 is operated in the lean condition, the thermal efficiency can be improved. Since the condensate can be used as a reducing agent by supplying the condensate to the ternary catalyst 72, the condensate can be effectively treated. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a reformed gas engine system.

  Conventionally, the following is known as a reformed gas engine system (see, for example, Patent Document 1).

For example, in the example described in Patent Document 1, a trap that is provided in a reformed gas passage that supplies reformed gas to an engine and that stores the condensed liquid of the reformed gas, and the trapped condensate reaches a predetermined amount or more. And a condensate reflux pipe for recirculating the condensate to the reformer.
JP 59-99058 A

  However, in the example described in Patent Document 1, the components contained in the condensate include reformed gas generation conditions (for example, the temperature of the reforming catalyst, the amount of hydrocarbon fuel and water supplied to the reforming catalyst, etc.) ) Greatly changes. For this reason, depending on the generation conditions of the reformed gas, the condensate may contain a water vapor component mainly without containing a hydrocarbon component.

  However, in such a case, even if the condensate is refluxed to the reforming catalyst, a large amount of water vapor component contained in the reformed gas generated by the reforming catalyst is only condensed again by the gas cooler. Thus, it is impossible to treat the condensate effectively.

  Further, in this type of reformed gas engine system, it is desirable that the thermal efficiency can be improved.

  This invention is made | formed in view of the said subject, Comprising: It aims at providing the reformed gas engine system which can process a condensate effectively, improving thermal efficiency.

  In order to solve the above-mentioned problem, a reformed gas engine system according to claim 1 includes a raw material tank for storing a reformed raw material containing water and hydrocarbon fuel, and a reformed raw material supplied from the raw material tank. An evaporator that evaporates water, a reforming catalyst that generates reformed gas from the reformed raw material evaporated in the evaporator, and a steam component and a specific hydrocarbon component from the reformed gas generated in the reforming catalyst A condenser for storing a condensate containing the separated water vapor component and the specific hydrocarbon component, and a reformed gas from which the water vapor component and the specific hydrocarbon component are separated by the condenser A gas injection valve capable of adjusting the amount of reformed gas to be injected while being injected into the cylinder of the engine; a throttle valve for adjusting the amount of air supplied into the cylinder of the engine; and the engine A three-way catalyst for purifying exhaust gas exhausted from the engine cylinder, and a condensate stored in the condenser upstream of the three-way catalyst in the exhaust passage. When the amount of condensate stored in the condenser and the amount of condensate stored in the condenser are within a predetermined range, the engine uses the reformed gas as a fuel and performs stoichiometric conditions. The reformed gas stoichiometric combustion mode for controlling the gas injection valve and the throttle valve is selected so that the gas injection valve and the throttle valve are operated, and the amount of condensate stored in the condenser is higher than the upper limit of the predetermined amount range. And the gas injection valve and the throttle valve are controlled so that the engine is operated under lean conditions using the reformed gas as fuel. A control unit that selects a reformed gas lean combustion mode for controlling the condensate supply device so that the condensate stored in the condenser is supplied to the upstream side of the three-way catalyst in the exhaust passage. Yes.

  In the reformed gas engine system according to the first aspect, the reformed raw material containing water and hydrocarbon fuel is stored in the raw material tank, and the reformed raw material supplied from the raw material tank is evaporated by the evaporator. The reforming material evaporated in the evaporator is supplied to the reforming catalyst, and the reforming gas is generated from the reforming material in the reforming catalyst.

  In addition, the reformed gas generated by the reforming catalyst is supplied to a condenser, and in this condenser, a water vapor component and a specific hydrocarbon component are separated from the reformed gas. The separated condensate containing the water vapor component and the specific hydrocarbon component is stored in the condenser.

  Further, the reformed gas from which the water vapor component and the specific hydrocarbon component are separated by the condenser is injected into the engine cylinder by the gas injection valve. As a result, the engine is operated using the reformed gas as fuel.

  Here, the control unit selects the reformed gas stoichiometric combustion mode when the amount of the condensate stored in the condenser is within a predetermined range. In this case, the control unit controls the gas injection valve and the throttle valve so that the engine is operated under the stoichiometric condition using the reformed gas as fuel. Thus, the engine is operated under the stoichiometric condition using the reformed gas as fuel, and the exhaust gas discharged from the engine cylinder is purified by the three-way catalyst.

  On the other hand, the control unit selects the reformed gas lean combustion mode when the amount of the condensate stored in the condenser is within another predetermined amount range whose upper limit is higher than the upper limit of the predetermined amount range. In this case, the control unit controls the gas injection valve and the throttle valve so that the engine is operated under the lean condition using the reformed gas as fuel. Therefore, since the engine is operated not only under the stoichiometric condition but also under the lean condition, the thermal efficiency can be improved as compared with the case where the engine is operated only under the stoichiometric condition.

  By the way, as described above, when the engine is operated under the lean condition using the reformed gas as a fuel, the oxygen concentration in the exhaust gas discharged from the cylinder of the engine is higher than that when the engine is operated under the stoichiometric condition. Get higher.

  Therefore, when the reformed gas lean combustion mode is selected, the control unit controls the condensate supply device so that the condensate stored in the condenser is supplied to the upstream side of the three-way catalyst in the exhaust passage.

  As a result, the specific hydrocarbon component (high boiling point hydrocarbon component) in the condensate evaporated in the three-way catalyst reacts with oxygen in the exhaust gas supplied to the three-way catalyst, and the exhaust gas that passes through the three-way catalyst. The oxygen concentration in the gas decreases (concentration close to that when the engine is operated under stoichiometric conditions).

  As a result, even when the engine is operated under the lean condition using the reformed gas as a fuel, the exhaust gas discharged from the cylinder of the engine can be effectively purified by the three-way catalyst. Moreover, as mentioned above, this condensate can be effectively processed by using the condensate as a reducing agent.

  Thus, according to the reformed gas engine system of the first aspect, the condensate can be effectively processed while improving the thermal efficiency.

  A reformed gas engine system according to a second aspect is the reformed gas engine system according to the first aspect, wherein the control unit includes an exhaust gas that passes through the three-way catalyst in the reformed gas lean combustion mode. The condensate supply device is controlled to adjust the amount of condensate supplied to the upstream side of the three-way catalyst in the exhaust passage so that oxygen is consumed.

  According to the reformed gas engine system of claim 2, even when the engine is operated under the lean condition using the reformed gas as a fuel, the amount of condensate supplied to the upstream side of the three-way catalyst in the exhaust passage is reduced. By adjusting, oxygen in the exhaust gas passing through the three-way catalyst is consumed (that is, for example, the oxygen concentration in the exhaust gas passing through the three-way catalyst is the same as in the reformed gas stoichiometric combustion mode). )

  As a result, the exhaust gas discharged from the cylinder of the engine can be purified more effectively by the three-way catalyst, and the condensate can be treated more effectively.

  The reformed gas engine system according to claim 3 is the reformed gas engine system according to claim 1 or 2, wherein the hydrocarbon fuel supplied from the raw material tank is injected into a cylinder of the engine. A fuel injection valve capable of adjusting the amount of hydrocarbon fuel to be injected, and a reformer provided between the condenser and the gas injection valve, wherein a water vapor component and a specific hydrocarbon component are separated by the condenser A gas storage tank for storing gas, and when the control unit has a pressure of the reformed gas stored in the gas storage tank within a predetermined pressure range, the engine Is configured to select a hydrocarbon fuel combustion mode for controlling the fuel injection valve and the throttle valve so as to be operated using the hydrocarbon fuel as fuel.

  In the reformed gas engine system according to claim 3, a gas storage tank is provided between the condenser and the gas injection valve, and the reformed gas in which the water vapor component and the specific hydrocarbon component are separated by the condenser. Is stored in this gas storage tank.

  Here, the control unit selects the hydrocarbon fuel combustion mode when the pressure of the reformed gas stored in the gas storage tank is within a predetermined pressure range. In this case, the control unit controls the fuel injection valve and the throttle valve so that the engine is operated using hydrocarbon fuel as fuel.

  Thus, according to the reformed gas engine system of the third aspect, when the pressure of the reformed gas stored in the gas storage tank is within a predetermined pressure range, the engine is hydrocarbon. The fuel can be operated as fuel.

  The reformed gas engine system according to claim 4 is the reformed gas engine system according to claim 3, wherein the control unit is configured to control the amount of condensate stored in the condenser in the hydrocarbon fuel combustion mode. Is within the predetermined amount range, a hydrocarbon fuel stoichiometric combustion mode for controlling the fuel injection valve and the throttle valve is selected so that the engine is operated under stoichiometric conditions using the hydrocarbon fuel as fuel. In the hydrocarbon fuel combustion mode, when the amount of condensate stored in the condenser is within the other predetermined amount range, the engine is operated under lean conditions using the hydrocarbon fuel as fuel. And controlling the fuel injection valve and the throttle valve so that the condensate stored in the condenser is the ternary in the exhaust passage. Wherein selecting a hydrocarbon fuel lean combustion mode for controlling the condensate supply device is supplied to the upstream side for medium has the structure.

  5. The reformed gas engine system according to claim 4, wherein, in the hydrocarbon fuel combustion mode, when the amount of condensate stored in the condenser is within the predetermined amount range in the hydrocarbon fuel combustion mode, the control unit A hydrocarbon fuel stoichiometric combustion mode is further selected from the combustion modes.

  In this case, the control unit controls the fuel injection valve and the throttle valve so that the engine is operated under a stoichiometric condition using hydrocarbon fuel as fuel. As a result, the engine is operated under a stoichiometric condition using hydrocarbon fuel as fuel, and the exhaust gas discharged from the cylinder of the engine is purified by the three-way catalyst.

  On the other hand, in the hydrocarbon fuel combustion mode, when the amount of the condensate stored in the condenser is within another predetermined amount range whose upper limit is higher than the upper limit of the predetermined amount range, the control unit A hydrocarbon fuel lean combustion mode is further selected from the fuel combustion modes.

  In this case, the control unit controls the fuel injection valve and the throttle valve so that the engine is operated under lean conditions using hydrocarbon fuel as fuel. Therefore, since the engine is operated not only under the stoichiometric condition but also under the lean condition, the thermal efficiency can be improved as compared with the case where the engine is operated only under the stoichiometric condition.

  By the way, as described above, when the engine is operated under lean conditions using hydrocarbon fuel as fuel, the oxygen concentration in the exhaust gas discharged from the cylinder of the engine is higher than that when the engine is operated under stoichiometric conditions. Get higher.

  Therefore, when the hydrocarbon fuel lean combustion mode is selected, the control unit controls the condensate supply device so that the condensate stored in the condenser is supplied to the upstream side of the three-way catalyst in the exhaust passage. .

  As a result, the specific hydrocarbon component (high boiling point hydrocarbon component) in the condensate evaporated in the three-way catalyst reacts with oxygen in the exhaust gas supplied to the three-way catalyst, and the exhaust gas that passes through the three-way catalyst. The oxygen concentration in the gas decreases (concentration close to that when the engine is operated under stoichiometric conditions).

  As a result, even when the engine is operated under lean conditions using hydrocarbon fuel as fuel, the exhaust gas discharged from the engine cylinder can be effectively purified by the three-way catalyst. Moreover, as mentioned above, this condensate can be effectively processed by using the condensate as a reducing agent.

  Thus, according to the reformed gas engine system of the fourth aspect, the condensate can be effectively processed while improving the thermal efficiency even when the engine is operated using hydrocarbon fuel as fuel. .

  The reformed gas engine system according to claim 5 is the reformed gas engine system according to claim 4, wherein the control unit is in the exhaust gas that passes through the three-way catalyst in the hydrocarbon fuel lean combustion mode. The condensate supply device is controlled to adjust the amount of condensate supplied to the upstream side of the three-way catalyst in the exhaust passage so that the oxygen is consumed.

  According to the reformed gas engine system of the fifth aspect, even when the engine is operated under a lean condition using hydrocarbon fuel as a fuel, the amount of condensate supplied upstream of the three-way catalyst in the exhaust passage is reduced. By adjusting, oxygen in the exhaust gas passing through the three-way catalyst is consumed (that is, for example, the oxygen concentration in the exhaust gas passing through the three-way catalyst is the same as in the hydrocarbon fuel stoichiometric combustion mode). )

  As a result, the exhaust gas discharged from the cylinder of the engine can be purified more effectively by the three-way catalyst, and the condensate can be treated more effectively.

  The reformed gas engine system according to claim 6 is the reformed gas engine system according to any one of claims 3 to 5, wherein the control unit stores the reformed gas stored in the gas storage tank. When the gas pressure is in another predetermined pressure range whose upper limit is higher than the upper limit of the predetermined pressure range, the reformed gas stoichiometric combustion mode or the reformed gas lean combustion mode is selected.

  According to the reformed gas engine system of the sixth aspect, the control unit is configured so that the pressure of the reformed gas stored in the gas storage tank is within another predetermined pressure range where the upper limit is higher than the upper limit of the predetermined pressure range. If it is, the reformed gas stoichiometric combustion mode or the reformed gas lean combustion mode is selected. Thereby, thermal efficiency can be improved compared with the case where an engine is operated only with hydrocarbon fuel.

  The reformed gas engine system according to claim 7 is the reformed gas engine system according to any one of claims 1 to 6, wherein the raw material tank is a water tank for storing water; And a fuel tank for storing hydrocarbon fuel, and further comprising a condensate reflux device for refluxing the condensate stored in the condenser to the evaporator or the water tank.

  According to the reformed gas engine system of the seventh aspect, the condensate stored in the condenser can be returned to the evaporator or the water tank by the condensate recirculation device. Can be reused to do.

  As described above in detail, according to the present invention, the condensate can be effectively processed while improving the thermal efficiency.

[First embodiment]
First, a first embodiment of the present invention will be described.

  FIG. 1 shows an overall configuration of a reformed gas engine system S1 according to the first embodiment of the present invention. As shown in this figure, the reformed gas engine system S1 includes a fuel tank 12 and a water tank 14 as raw material tanks, pumps 16 and 18, flow control valves 20 and 22, an evaporator 24, a reformer, and the like. Catalyst 26, heat exchangers 28 and 30, condenser 32, pumps 34 and 36, gas storage tank 38, gas injection valve 40, fuel injection valve 42, engine 44, and condensate supply device 46. An upper liquid level sensor 48, a lower liquid level sensor 50, an upstream oxygen concentration sensor 52, a downstream oxygen concentration sensor 54, and an ECU 56 as a control unit.

  The fuel tank 12 stores, for example, hydrocarbon fuel such as gasoline, light oil, methane, propane, methanol, and ethanol, and the water tank 14 stores water. The hydrocarbon fuel and water are used as a reforming raw material for generating a reformed gas described later.

  The pump 16 is provided between the fuel tank 12 and the evaporator 24, and is configured to supply hydrocarbon fuel stored in the fuel tank 12 to the evaporator 24. On the other hand, the pump 18 is provided between the water tank 14 and the evaporator 24, and is configured to supply the water stored in the water tank 14 to the evaporator 24.

  The flow control valve 20 is provided between the pump 16 and the evaporator 24, and is configured to be able to control the supply amount of hydrocarbon fuel stored in the fuel tank 12 to the evaporator 24. On the other hand, the flow control valve 22 is provided between the pump 18 and the evaporator 24, and is configured to be able to control the supply amount of the water stored in the water tank 14 to the evaporator 24.

  The evaporator 24 is heated by the heat exchanger 28 to evaporate the hydrocarbon fuel supplied from the fuel tank 12 and the water supplied from the water tank 14 and supply the evaporated fuel to the reforming catalyst 26.

  The reforming catalyst 26 is heated by the heat exchanger 30 and is configured to generate reformed gas from the hydrocarbon fuel and water vapor gas supplied from the evaporator 24. The reformed gas in this case is mainly composed of, for example, hydrogen, carbon monoxide, methane, carbon dioxide, a water vapor component, and the like. Further, the composition of the reformed gas varies depending on the temperature of the reforming catalyst 26 (see FIG. 2).

  The heat exchangers 28 and 30 are integrally attached to an exhaust passage 68 provided in the engine 44 described later. The heat exchanger 28 is configured to heat the evaporator 24 using the heat energy of the exhaust gas flowing through the exhaust passage 68, and the heat exchanger 30 uses the heat energy of the exhaust gas flowing through the exhaust passage 68. Thus, the reforming catalyst 26 is heated.

  The condenser 32 separates the steam component and the specific hydrocarbon component (high boiling point hydrocarbon component) from the reformed gas generated by the reforming catalyst 26, and contains the separated steam component and the specific hydrocarbon component. The condensate is stored.

For example, the specific hydrocarbon component (high-boiling hydrocarbon component) contained in a small amount in the reformed gas generated when ethanol is reformed with steam is as follows. That is, for example, ethyl acetate (C ₄ H ₈ O ₂ / boiling point 77.1 ° C.), ethanol (C ₂ H ₅ OH / boiling point 78 ° C.), 2-pentanone (C ₅ H ₁₀ O / boiling point 101.7 ° C.) , Acetic acid (CH ₃ COOH / boiling point 118 ° C.), n-butyric acid (C ₄ H ₈ O ₂ / boiling point 164 ° C.), cresol (C ₇ H ₈ O / boiling point about 200 ° C.).

  The pump 34 is provided between the condenser 32 and the gas storage tank 38, and is configured to supply the reformed gas generated in the condenser 32 to the gas storage tank 38. On the other hand, the pump 36 is provided between the fuel tank 12 and the fuel injection valve 42, and is configured to supply hydrocarbon fuel stored in the fuel tank 12 to the fuel injection valve 42.

  The gas storage tank 38 is provided between the condenser 32 and the gas injection valve 40 and can temporarily store the reformed gas from which the water vapor component and the specific hydrocarbon component are separated by the condenser 32. The stored reformed gas is supplied to the gas injection valve 40.

  The gas injection valve 40 is configured to inject the reformed gas stored in the gas storage tank 38 into the cylinder 58 of the engine 44 and to adjust the amount of the reformed gas to be injected. On the other hand, the fuel injection valve 42 is configured to inject hydrocarbon fuel stored in the fuel tank 12 into the cylinder 58 of the engine 44 and to adjust the amount of hydrocarbon fuel to be injected.

  The engine 44 includes a cylinder 58, a spark plug 60, an intake valve 62, an exhaust valve 64, and the like. The engine 44 is connected to an intake passage 66 and an exhaust passage 68.

  In addition to the gas injection valve 40 and the fuel injection valve 42 described above, the intake passage 66 is provided with a throttle valve 70 for adjusting the amount of air supplied into the cylinder 58 of the engine 44. On the other hand, the exhaust passage 68 is provided with a three-way catalyst 72 for purifying exhaust gas (especially hydrocarbon, carbon monoxide, nitrogen oxide) exhausted from the cylinder 58 of the engine 44.

  The condensate supply device 46 includes a pump 74 and a condensate injection valve 76. The pump 74 is configured to supply the condensate stored in the condenser 32 to the condensate injection valve 76, which condenses the condensate supplied from the pump 74 in the exhaust passage 68. While being injected to the upstream with respect to the catalyst 72, it is the structure which can adjust the quantity of the condensate to inject.

  The upper liquid level sensor 48 and the lower liquid level sensor 50 are provided integrally at the upper and lower parts of the condenser 32, respectively, and output signals corresponding to the amount of condensate (liquid level) stored in the condenser 32. It is configured to output.

  The upstream oxygen concentration sensor 52 and the downstream oxygen concentration sensor 54 are provided on the upstream side and the downstream side with respect to the three-way catalyst 72 in the exhaust passage 68, and a signal corresponding to the oxygen concentration in the exhaust gas passing through the exhaust passage 68 is provided. It is configured to output.

  The ECU 56 controls the flow rate control valves 20 and 22 and the pumps 16, 18, 34, and 36 based on output signals from the above-described upper liquid level sensor 48, lower liquid level sensor 50, upstream oxygen concentration sensor 52, downstream oxygen concentration sensor 54, and the like. 74, the gas injection valve 40, the fuel injection valve 42, the condensate injection valve 76, the throttle valve 70, and the like.

  Next, the operation and effect will be described together with the operation of the reformed gas engine system S1 configured as described above.

  In the reformed gas engine system S1, when the pumps 16 and 18 and the flow control valves 20 and 22 are controlled by the ECU 56, water and hydrocarbon fuel are supplied from the water tank 14 and the fuel tank 12 to the evaporator 24. Water and hydrocarbon fuel are evaporated in the evaporator 24. The water and hydrocarbon fuel evaporated in the evaporator 24 are supplied to the reforming catalyst 26, and the reforming gas is generated from the water and hydrocarbon fuel in the reforming catalyst 26.

  Further, the reformed gas generated by the reforming catalyst 26 is supplied to a condenser 32, and in this condenser 32, a water vapor component and a specific hydrocarbon component (high boiling point hydrocarbon component) are separated from the reformed gas. The The separated condensate containing the water vapor component and the specific hydrocarbon component is stored in the condenser 32.

  The reformed gas from which the water vapor component and the specific hydrocarbon component are separated by the condenser 32 is supplied to the gas storage tank 38 by the pump 34 and stored in the gas storage tank 38. The gas stored in the gas storage tank 38 is supplied to the gas injection valve 40 and is injected into the cylinder 58 of the engine 44 by the gas injection valve 40. As a result, the engine 44 is operated using the reformed gas as fuel.

  Here, as described above, the ECU 56 executes the processing of the program shown in the flowchart of FIG. 3 when the engine 44 is operated using the reformed gas as fuel.

That is, the ECU 56 first detects the output signal of the upper liquid level sensor 48 (step ST1), and determines whether the liquid level L of the condensate is higher than the level L _{H at} which the upper liquid level sensor 48 is provided. Judgment is made (step ST2).

Here, the ECU 56 determines that the liquid level L of the condensate is not higher than the level L _H provided with the upper liquid level sensor 48 (step ST2: NO), that is, when L ≦ L _H. Selects the reformed gas stoichiometric combustion mode (step ST3).

Meanwhile, ECU 56, when the liquid surface level L of the condensate was determined to be higher than the level _{L H} provided with the upper liquid level sensor 48 (step ST2: YES), that is, in the case of L> _{L H} is The reformed gas lean combustion mode is selected (step ST8).

  Hereinafter, the reformed gas stoichiometric combustion mode and the reformed gas lean combustion mode will be described.

(Reformed gas stoichiometric combustion mode)
When the reformed gas stoichiometric combustion mode is selected in step ST3, the ECU 56 detects the output signal of the upstream oxygen concentration sensor 52 (step ST4), and whether the engine 44 is operated under the stoichiometric condition using the reformed gas as fuel. It is determined whether or not (step ST5).

  Here, when the ECU 56 determines that the engine 44 is not operated under the stoichiometric condition using the reformed gas as fuel (step ST5: NO), the engine 44 is operated under the stoichiometric condition using the reformed gas as fuel. Thus, while adjusting the opening degree of the throttle valve 70 (step ST6), the injection period of the gas injection valve 40 is adjusted (step ST7).

  The adjustment of the opening degree of the throttle valve 70 and the injection period of the gas injection valve 40 is performed based on data such as a map stored in advance in the ECU 56 in accordance with the driving situation of the vehicle.

  Incidentally, the stoichiometric condition in this case is not limited to a perfect stoichiometric air-fuel ratio, but includes a broad meaning.

  Then, the ECU 56 repeats the above-described steps ST4 to ST7 until it is determined in step ST5 that the engine 44 is operated under the stoichiometric condition using the reformed gas as fuel.

  On the other hand, if the ECU 56 determines that the engine 44 is operated under the stoichiometric condition using the reformed gas as a fuel (step ST5: YES), the processing of the program shown in the flowchart of FIG.

  As described above, when the reformed gas stoichiometric combustion mode is selected, the ECU 56 controls the gas injection valve 40 and the throttle valve 70 so that the engine 44 is operated under the stoichiometric condition using the reformed gas as fuel. As a result, the engine 44 is operated under the stoichiometric condition using the reformed gas as fuel, and the exhaust gas discharged from the cylinder 58 of the engine 44 is purified by the three-way catalyst 72.

(Reformed gas lean combustion mode)
On the other hand, when the reformed gas lean combustion mode is selected in step ST8, the ECU 56 adjusts the opening degree of the throttle valve 70 so that the engine 44 is operated under the lean condition using the reformed gas as fuel (step ST8). ST9), the injection period of the gas injection valve 40 is adjusted (step ST10).

  The adjustment of the opening degree of the throttle valve 70 and the injection period of the gas injection valve 40 is performed based on data such as a map stored in advance in the ECU 56 in accordance with the driving situation of the vehicle.

  Then, the ECU 56 detects the output signal of the upstream oxygen concentration sensor 52 (step ST11), and determines whether or not the concentration of the air-fuel mixture in the engine 44 is appropriate as lean combustion (step ST12).

  Here, when the ECU 56 determines that the concentration of the air-fuel mixture in the engine 44 is not appropriate as lean combustion (step ST12: NO), the ECU 56 determines that the concentration of the air-fuel mixture in the engine 44 is appropriate as lean combustion. Until this is done, the above-described steps ST9 to ST12 are repeated.

  As described above, when the reformed gas lean combustion mode is selected, the ECU 56 controls the gas injection valve 40 and the throttle valve 70 so that the engine 44 is operated under the lean condition using the reformed gas as fuel. Therefore, since the engine 44 is operated not only under the stoichiometric condition but also under the lean condition, the thermal efficiency can be improved as compared with the case where the engine 44 is operated only under the stoichiometric condition.

  By the way, as described above, when the engine 44 is operated under the lean condition using the reformed gas as a fuel, the oxygen concentration in the exhaust gas discharged from the cylinder 58 of the engine 44 is the case where the engine 44 is operated under the stoichiometric condition. Higher than

  Therefore, when the reformed gas lean combustion mode is selected, the ECU 56 controls the pump 74 and the condensate injection valve 76 (condensate supply device 46) (step ST13), and condenses the condensate in the exhaust passage 68. Injected upstream of 72.

  As a result, the condensate is supplied to the three-way catalyst 72, the specific hydrocarbon component (high-boiling point hydrocarbon component) in the condensate evaporated in the three-way catalyst 72, and the exhaust gas supplied to the three-way catalyst 72. Oxygen reacts and the oxygen concentration in the exhaust gas passing through the three-way catalyst 72 decreases (concentration close to that when the engine 44 is operated under stoichiometric conditions).

  As a result, even when the engine 44 is operated under the lean condition using the reformed gas as a fuel, the exhaust gas discharged from the cylinder 58 of the engine 44 can be effectively purified by the three-way catalyst 72. Moreover, as mentioned above, this condensate can be effectively processed by using the condensate as a reducing agent.

  Subsequently, the ECU 56 detects the output signal of the downstream oxygen concentration sensor 54 (step ST14), and the oxygen concentration in the exhaust gas passing through the three-way catalyst 72 becomes the same as in the above-described reformed gas stoichiometric combustion mode. Whether or not oxygen in the exhaust gas passing through the three-way catalyst 72 is consumed (step ST15).

  When the ECU 56 determines that the oxygen concentration in the exhaust gas passing through the three-way catalyst 72 is not the same as that in the above-described reformed gas stoichiometric combustion mode (step ST15: NO), the three-way The injection period of the condensate injection valve 76 is adjusted so that the oxygen concentration in the exhaust gas passing through the catalyst 72 becomes the same as in the above-described reformed gas stoichiometric combustion mode (step ST16).

  Then, the ECU 56 repeats the above steps ST14 to ST16 until it determines that the oxygen concentration in the exhaust gas passing through the three-way catalyst 72 is the same as in the above-described reformed gas stoichiometric combustion mode.

  Therefore, even when the engine 44 is operated under the lean condition using the reformed gas as a fuel, the amount of the condensate supplied to the three-way catalyst 72 is adjusted so that the exhaust gas in the exhaust gas passing through the three-way catalyst 72 is adjusted. The oxygen concentration is the same as in the reformed gas stoichiometric combustion mode.

  As a result, the exhaust gas discharged from the cylinder 58 of the engine 44 can be more effectively purified by the three-way catalyst 72, and the condensate can be treated more effectively.

On the other hand, when the ECU 56 determines that the oxygen concentration in the exhaust gas passing through the three-way catalyst 72 is the same as in the above-described reformed gas stoichiometric combustion mode (step ST15: YES), the lower liquid level An output signal of the sensor 50 is detected (step ST17), and it is determined whether or not the liquid level L of the condensate is higher than the level L _L provided with the lower liquid level sensor 50 (step ST18).

Here, ECU 56, when the liquid surface level L of the condensate was determined to be higher than the level _{L L} provided with the lower liquid level sensor 50 (step ST18: YES), that is, in the case of L> _{L L} is The process returns to step ST8 described above. That is, in the ECU 56, the reformed gas lean combustion mode is continued.

On the other hand, when the ECU 56 determines that the liquid level L of the condensate is not higher than the level L _L provided with the lower liquid level sensor 50 (step ST18: NO), that is, when L ≦ L _L. Then, the pump 74 and the condensate injection valve 76 (condensate supply device 46) are stopped (step ST19), and the process proceeds to the above-described step ST3. That is, the ECU 56 switches from the reformed gas lean combustion mode to the reformed gas stoichiometric combustion mode.

  The ECU 56 switches between the reformed gas stoichiometric combustion mode and the reformed gas lean combustion mode according to the amount of condensate stored in the condenser 32 until the processing of the program shown in the flowchart of FIG.

That, ECU 56 (at the upper limit L1 is L1 ≦ _{L H,} lower L2 is L2 ≦ _{L L)} condenser 32 is stored in the condensate within a predetermined weight range amounts predetermined for the case in the modified Select the quality gas stoichiometric combustion mode. Further, ECU 56, respectively high other predetermined amount range between the upper and lower than the upper limit and the lower limit of the amount of stored in the condenser 32 the condensate predetermined amount within the above range (the upper limit L3 is at L3> L _H, lower L4 is L4> in some cases in L _L scope) within selects reforming Gasurin combustion mode.

  As a result, according to the reformed gas engine system S1 according to the first embodiment of the present invention, it is possible to effectively process the condensate while improving the thermal efficiency.

  In addition to the above, the reformed gas engine system S1 according to the first embodiment of the present invention has the following effects.

  In other words, in a reformed gas engine system that generally does not include a condenser, the steam component and the specific hydrocarbon component (high-boiling hydrocarbon component) in the reformed gas condense near the gas injection valve, and gas-liquid reforming is performed. Gas may be injected from the gas injection valve. Even in the reformed gas engine system provided with a condenser, the same problem as described above occurs if the condensate is not properly processed.

  On the other hand, according to the reformed gas engine system S1 according to the first embodiment of the present invention, the gas component and the condensate component of the reformed gas are appropriately separated by the condenser 32 as described above. In addition, accurate control of the injection amount of the gas injection valve 40 can be performed.

  In addition, according to the reformed gas engine system S1 according to the first embodiment of the present invention, the condensate can be prevented from being burned by the engine 44. Therefore, in the engine 44, the combustion deteriorates due to the water vapor component in the reformed gas. Can be suppressed, and stable combustion can be realized.

[Second Embodiment]
Next, a second embodiment of the present invention will be described.

  FIG. 4 shows the overall configuration of the reformed gas engine system S2 according to the second embodiment of the present invention. The reformed gas engine system S2 according to the second embodiment of the present invention shown in this figure includes a pressure sensor 78 with respect to the reformed gas engine system S1 according to the first embodiment of the present invention described above, The ECU 56 is configured to operate as follows.

  That is, the pressure sensor 78 is provided integrally with the gas storage tank 38 and outputs a signal corresponding to the pressure in the gas storage tank 38.

  In addition to the upper liquid level sensor 48, the lower liquid level sensor 50, the upstream oxygen concentration sensor 52, the downstream oxygen concentration sensor 54, and the like, the ECU 56 controls the flow rate control valves 20 and 22 based on the output signal of the pressure sensor 78. The pumps 16, 18, 34, 36, 74, the gas injection valve 40, the fuel injection valve 42, the condensate injection valve 76, the throttle valve 70, and the like are controlled.

  Next, the operation and effect will be described together with the operation of the reformed gas engine system S2 configured as described above.

  In the reformed gas engine system S2, the ECU 56 executes the processing of the program shown in the flowchart of FIG. 5 when the engine 44 is operated using the reformed gas as fuel.

That, ECU 56, first, detects the output signal of the pressure sensor 78 (step ST21), whether or not higher than the predetermined pressure P _L to the pressure P of the stored reformed gas in gas storage tank 38 reaches a predetermined Is determined (step ST22).

Here, ECU 56, when it is determined that higher than the predetermined pressure _{P L} to the pressure P in the gas storage tank 38 reaches a predetermined (step ST22: YES), that is, in the case of P> _{P L} is modified The gas combustion mode is continued (step ST50). In this case, the ECU 56 executes the processing of the program shown in the flowchart of FIG.

Meanwhile, ECU 56, when the pressure P in the gas storage tank 38 is determined to not higher than the predetermined pressure _{P L} (step ST22: NO), that is, in the case of P ≦ _{P L} is a hydrocarbon fuel combustion mode Select (step ST23).

  Hereinafter, the hydrocarbon fuel combustion mode will be described in more detail.

(Hydrocarbon fuel combustion mode)
When the hydrocarbon fuel combustion mode is selected in step ST23, the ECU 56 stops the gas injection valve 40 (step ST24), controls the fuel injection valve 42, and injects hydrocarbon fuel from the fuel injection valve 42. (Step ST25).

  Subsequently, the ECU 56 adjusts the opening of the throttle valve 70 (step ST26) and adjusts the injection period of the fuel injection valve 42 (step ST27) so that the engine 44 is operated using hydrocarbon fuel as fuel. .

  The adjustment of the opening degree of the throttle valve 70 and the injection period of the fuel injection valve 42 is performed based on data such as a map stored in advance in the ECU 56 in accordance with the driving situation of the vehicle.

Thus, according to the reformed gas engine system S2, according to the second embodiment of the present invention, when the pressure P in the gas storage tank 38 is not higher than the predetermined pressure P _L is the engine 44 hydrocarbon fuels Can be operated as fuel.

Then, the ECU 56 detects the output signal of the upper liquid level sensor 48 (step ST31), and determines whether or not the liquid level L of the condensed liquid is higher than the level L _{H at} which the upper liquid level sensor 48 is provided. (Step ST32).

Here, the ECU 56 determines that the liquid level L of the condensate is not higher than the level L _{H at} which the upper liquid level sensor 48 is provided (step ST32: NO), that is, when L ≦ L _H. Selects a hydrocarbon fuel stoichiometric combustion mode among the hydrocarbon fuel combustion modes (step ST33).

Meanwhile, ECU 56, when the liquid surface level L of the condensate was determined to be higher than the level _{L H} provided with the upper liquid level sensor 48 (step ST32: YES), that is, in the case of L> _{L H} is A hydrocarbon fuel lean combustion mode is further selected from the hydrocarbon fuel combustion modes (step ST38).

  Hereinafter, the hydrocarbon fuel stoichiometric combustion mode and the hydrocarbon fuel lean combustion mode will be described.

(Hydrocarbon fuel stoichiometric combustion mode)
If the hydrocarbon fuel stoichiometric combustion mode is selected in step ST33, the ECU 56 detects the output signal of the upstream oxygen concentration sensor 52 (step ST34), and the engine 44 is operated under the stoichiometric condition using hydrocarbon fuel as fuel. It is determined whether or not (step ST35).

  Here, when the ECU 56 determines that the engine 44 is not operated under a stoichiometric condition using hydrocarbon fuel as a fuel (step ST35: NO), the engine 44 is operated under a stoichiometric condition using hydrocarbon fuel as a fuel. Thus, while adjusting the opening degree of the throttle valve 70 (step ST36), the injection period of the fuel injection valve 42 is adjusted (step ST37).

  The adjustment of the opening degree of the throttle valve 70 and the injection period of the fuel injection valve 42 is performed based on data such as a map stored in advance in the ECU 56 in accordance with the driving situation of the vehicle.

  Incidentally, the stoichiometric condition in this case is not limited to a perfect stoichiometric air-fuel ratio, but includes a broad meaning.

  Then, the ECU 56 repeats the above-described steps ST34 to ST37 until it is determined in step ST35 that the engine 44 is operated under the stoichiometric condition using hydrocarbon fuel as fuel.

  On the other hand, when ECU 56 determines that engine 44 is operated under the stoichiometric condition using hydrocarbon fuel as fuel (step ST35: YES), the processing of the program shown in the flowchart of FIG. 5 is terminated.

  As described above, when the hydrocarbon fuel stoichiometric combustion mode is selected, the ECU 56 controls the fuel injection valve 42 and the throttle valve 70 so that the engine 44 is operated under stoichiometric conditions using hydrocarbon fuel as fuel. As a result, the engine 44 is operated under a stoichiometric condition using hydrocarbon fuel as fuel, and the exhaust gas discharged from the cylinder 58 of the engine 44 is purified by the three-way catalyst 72.

(Hydrocarbon fuel lean combustion mode)
On the other hand, when the hydrocarbon fuel lean combustion mode is selected in step ST38, the ECU 56 adjusts the opening of the throttle valve 70 so that the engine 44 is operated under lean conditions using hydrocarbon fuel as fuel ( Step ST39), the injection period of the fuel injection valve 42 is adjusted (step ST40).

  The adjustment of the opening degree of the throttle valve 70 and the injection period of the fuel injection valve 42 is performed based on data such as a map stored in advance in the ECU 56 in accordance with the driving situation of the vehicle.

  Then, the ECU 56 detects the output signal of the upstream oxygen concentration sensor 52 (step ST41), and determines whether or not the concentration of the air-fuel mixture in the engine 44 is appropriate as lean combustion (step ST42).

  If the ECU 56 determines that the concentration of the air-fuel mixture in the engine 44 is not appropriate for lean combustion (step ST42: NO), the ECU 56 determines that the concentration of the air-fuel mixture in the engine 44 is appropriate for lean combustion. The above-described steps ST39 to ST42 are repeatedly performed until this is done.

  In this way, when the hydrocarbon fuel lean combustion mode is selected, the ECU 56 controls the fuel injection valve 42 and the throttle valve 70 so that the engine 44 is operated under lean conditions using hydrocarbon fuel as fuel. Therefore, since the engine 44 is operated not only under the stoichiometric condition but also under the lean condition, the thermal efficiency can be improved as compared with the case where the engine 44 is operated only under the stoichiometric condition.

  By the way, as described above, when the engine 44 is operated under lean conditions using hydrocarbon fuel as fuel, the oxygen concentration in the exhaust gas discharged from the cylinder 58 of the engine 44 is the case where the engine 44 is operated under stoichiometric conditions. Higher than

  Therefore, when the hydrocarbon fuel lean combustion mode is selected, the ECU 56 controls the pump 74 and the condensate injection valve 76 (condensate supply device 46) (step ST43), and condenses the condensate in the exhaust passage 68. Injected upstream of the catalyst 72.

  As a result, the condensate is supplied to the three-way catalyst 72, the specific hydrocarbon component (high-boiling point hydrocarbon component) in the condensate evaporated in the three-way catalyst 72, and the exhaust gas supplied to the three-way catalyst 72. Oxygen reacts and the oxygen concentration in the exhaust gas passing through the three-way catalyst 72 decreases (concentration close to that when the engine 44 is operated under stoichiometric conditions).

  As a result, even when the engine 44 is operated under lean conditions using hydrocarbon fuel as fuel, the exhaust gas discharged from the cylinder 58 of the engine 44 can be effectively purified by the three-way catalyst 72. Moreover, as mentioned above, this condensate can be effectively processed by using the condensate as a reducing agent.

  Subsequently, the ECU 56 detects the output signal of the downstream oxygen concentration sensor 54 (step ST44), and the oxygen concentration in the exhaust gas passing through the three-way catalyst 72 is the same as in the above-described hydrocarbon fuel stoichiometric combustion mode (same as above). It is determined whether or not oxygen in exhaust gas passing through the three-way catalyst 72 is consumed (step ST45).

  When the ECU 56 determines that the oxygen concentration in the exhaust gas passing through the three-way catalyst 72 is not the same as that in the above-described hydrocarbon fuel stoichiometric combustion mode (step ST45: NO), the ECU 56 The injection period of the condensate injection valve 76 is adjusted so that the oxygen concentration in the exhaust gas passing through the original catalyst 72 is the same as in the above-described hydrocarbon fuel stoichiometric combustion mode (step ST46).

  Then, the ECU 56 repeatedly performs the above-described steps ST44 to ST46 until it determines that the oxygen concentration in the exhaust gas passing through the three-way catalyst 72 is the same as that in the above-described hydrocarbon fuel stoichiometric combustion mode. .

  Therefore, even when the engine 44 is operated under a lean condition using hydrocarbon fuel as fuel, the amount of condensate supplied to the three-way catalyst 72 is adjusted, so that the exhaust gas in the exhaust gas passing through the three-way catalyst 72 is adjusted. The oxygen concentration is the same as in the hydrocarbon fuel stoichiometric combustion mode.

  As a result, the exhaust gas discharged from the cylinder 58 of the engine 44 can be more effectively purified by the three-way catalyst 72, and the condensate can be more effectively processed.

On the other hand, when the ECU 56 determines that the oxygen concentration in the exhaust gas passing through the three-way catalyst 72 is the same as that in the above-described hydrocarbon fuel stoichiometric combustion mode (step ST45: YES), the lower liquid The output signal of the surface sensor 50 is detected (step ST47), and it is determined whether or not the liquid level L of the condensate is higher than the level L _L provided with the lower liquid level sensor 50 (step ST48).

Here, ECU 56, when the liquid surface level L of the condensate was determined to be higher than the level _{L L} provided with the lower liquid level sensor 50 (step ST48: YES), that is, in the case of L> _{L L} is The process returns to step ST38 described above. That is, in the ECU 56, the hydrocarbon fuel lean combustion mode is continued.

On the other hand, when the ECU 56 determines that the liquid level L of the condensate is not higher than the level L _L provided with the lower liquid level sensor 50 (step ST48: NO), that is, when L ≦ L _L. Then, the pump 74 and the condensate injection valve 76 (condensate supply device 46) are stopped (step ST49), and the process proceeds to the above-described step ST33. That is, the ECU 56 switches from the hydrocarbon fuel lean combustion mode to the hydrocarbon fuel stoichiometric combustion mode.

  Then, the ECU 56 switches between the hydrocarbon fuel stoichiometric combustion mode and the hydrocarbon fuel lean combustion mode according to the amount of the condensate stored in the condenser 32 until the processing of the program shown in the flowchart of FIG. .

That, ECU 56 (at the upper limit L1 is L1 ≦ _{L H,} lower L2 is L2 ≦ _{L L)} a predetermined amount range where the amount of stored condensate to the condenser 32 is predetermined in the case within the carbonized Select hydrogen fuel stoichiometric combustion mode. Further, ECU 56, respectively high other predetermined amount range between the upper and lower than the upper limit and the lower limit of the amount of stored in the condenser 32 the condensate predetermined amount within the above range (the upper limit L3 is at L3> L _H, lower L4 is L4 in some cases to> L _L scope) the selects a hydrocarbon fuel-lean combustion mode.

  As a result, according to the reformed gas engine system S2 according to the second embodiment of the present invention, even when the engine 44 is operated using hydrocarbon fuel as fuel, the condensate is effectively processed while improving the thermal efficiency. can do.

  By the way, as described above, even after the ECU 56 enters the hydrocarbon fuel combustion mode and the supply of the reformed gas to the engine 44 is stopped, the hydrocarbon fuel and water are continuously supplied to the evaporator 24. Accordingly, the pressure of the reformed gas stored in the gas storage tank 38 is restored.

  Therefore, the ECU 56 executes the program processing shown in the flowchart of FIG.

  That is, the ECU 56 first determines whether or not it is in the reformed gas combustion mode, that is, determines whether or not the fuel supplied to the engine 44 is reformed gas (step ST60).

  If the ECU 56 determines that it is in the reformed gas combustion mode (step ST60: YES), it executes the processing of the program shown in the flowchart of FIG.

  On the other hand, when ECU 56 determines that it is not the reformed gas combustion mode (step ST60: NO), that is, it is the hydrocarbon fuel combustion mode, and the fuel supplied to engine 44 is determined to be a hydrocarbon fuel. In that case, the output signal of the pressure sensor 78 is detected (step ST61).

Then, the ECU 56 determines whether or not the pressure P of the reformed gas stored in the gas storage tank 38 is higher than a predetermined pressure P _H (P _H > P _L ) (step ST62).

Here, ECU 56, when the pressure P of the reformed gas stored in the gas storage tank 38 is determined to not higher than the predetermined pressure _{P H} (step ST62: NO), that is, in the case of P ≦ _{P H} is Then, it is determined that the amount of the reformed gas has not recovered in the gas storage tank 38 (step ST63).

  In this case, the ECU 56 continues the hydrocarbon fuel combustion mode (step ST64).

That, ECU 56 (at the upper limit P1 is P1 ≦ _{P H,} lower range limit P2 is P2 ≦ _{P L)} a predetermined pressure range pressure P of the reformed gas stored in the gas storage tank 38 is determined in advance in the In some cases, a hydrocarbon fuel combustion mode is selected.

Meanwhile, ECU 56, when the pressure P of the stored reformed gas in gas storage tank 38 is determined to be higher than the predetermined pressure _{P H} (step ST62: YES), that is, in the case of P> _{P H,} the gas It is determined that the amount of the reformed gas has been recovered in the storage tank 38 (step ST72).

  When the ECU 56 determines that the amount of the reformed gas has recovered in the gas storage tank 38, the ECU 56 switches from the hydrocarbon fuel combustion mode to the reformed gas combustion mode (step ST73).

  Subsequently, the ECU 56 stops the fuel injection valve 42 (step ST74), controls the gas injection valve 40, and injects the reformed gas from the gas injection valve 40 (step ST75).

  Further, the ECU 56 adjusts the opening degree of the throttle valve 70 (step ST76) and adjusts the injection period of the gas injection valve 40 (step ST77) so that the engine 44 is operated using the reformed gas as fuel.

  The adjustment of the opening degree of the throttle valve 70 and the injection period of the gas injection valve 40 is performed based on data such as a map stored in advance in the ECU 56 in accordance with the driving situation of the vehicle.

  Thereafter, the ECU 56 executes the processing of the program shown in the flowchart of FIG.

That is, the ECU 56 determines that the pressure P of the reformed gas stored in the gas storage tank 38 is another predetermined pressure range in which the upper limit and the lower limit are higher than the upper limit and lower limit of the predetermined pressure range described above (the upper limit P3 is P3> P _H in the case where the lower limit P4 is in the range) in which the P4> P _L selects the reformed gas combustion mode. Thereby, thermal efficiency can be improved compared with the case where the engine 44 is operated only with hydrocarbon fuel.

[Third embodiment]
Next, a third embodiment of the present invention will be described.

  FIG. 7 shows the overall configuration of the reformed gas engine system S3 according to the third embodiment of the present invention. The reformed gas engine system S3 according to the third embodiment of the present invention shown in this figure is provided with a condensate recirculation device 80 with respect to the above-described reformed gas engine system S1 according to the first embodiment of the present invention. At the same time, the ECU 56 is configured to operate as follows.

  That is, the condensate reflux device 80 includes the pump 82 and the flow rate control valve 84. The pump 82 is configured to supply the condensate stored in the condenser 32 to the evaporator 24. On the other hand, the flow control valve 84 is provided between the pump 82 and the evaporator 24, and is configured to be able to control the supply amount of the condensate stored in the condenser 32 to the evaporator 24.

  Next, the operation and effect of the reformed gas engine system S3 having the above configuration will be described together with the operation.

  In this reformed gas engine system S3, the ECU 56 executes the processing of the program shown in the flowchart of FIG. 8 instead of the processing of the program shown in the flowchart of FIG.

  In the program processing shown in the flowchart of FIG. 8, the ECU 56 performs only steps ST13 and ST19 different from the processing of the program shown in the flowchart of FIG. 3, and other processing is shown in the flowchart of FIG. The same processing as that of the program to be executed is performed.

  That is, as described above, the ECU 56 controls the pump 74 and the condensate injection valve 76 (condensate supply device 46) to exhaust the condensate when the engine 44 is operated under the lean condition using the reformed gas as fuel. The fuel is injected to the upstream side of the three-way catalyst 72 in the passage 68, and the pump 82 and the flow rate control valve 84 (condensate recirculation device 80) are controlled to recirculate the condensate to the evaporator 24 (step ST13).

When the ECU 56 determines that the liquid level L of the condensate is not higher than the level L _L provided with the lower liquid level sensor 50 (step ST18: NO), as described above, the ECU 74 and the condensing liquid are used. The liquid injection valve 76 (condensate supply device 46) is stopped, and the pump 82 and the flow rate control valve 84 (condensate reflux device 80) are stopped (step ST19).

  Thus, according to the reformed gas engine system S3 according to the third embodiment of the present invention, the condensate stored in the condenser 32 can be refluxed to the evaporator 24 by the condensate reflux device 80. The condensate can be reused to produce reformed gas.

  The reformed gas engine system S3 according to the third embodiment of the present invention is provided with a condensate recirculation device 80 and an ECU 56 in addition to the above-described reformed gas engine system S2 according to the second embodiment of the present invention. May be configured to operate as described above.

[Fourth embodiment]
Next, a fourth embodiment of the present invention will be described.

  FIG. 9 shows an overall configuration of a reformed gas engine system S4 according to the fourth embodiment of the present invention. The reformed gas engine system S4 according to the fourth embodiment of the present invention shown in this figure has a condensate reflux device 80 configured as compared with the reformed gas engine system S3 according to the third embodiment of the present invention described above. In addition to the change, the ECU 56 is configured to operate as follows.

  That is, the pump 82 that constitutes the condensate reflux device 80 is configured to supply the condensate stored in the condenser 32 to the water tank 14. On the other hand, the flow control valve 84 is provided between the pump 82 and the water tank 14 and is configured to be able to control the supply amount of the condensate stored in the condenser 32 to the water tank 14.

  Next, the operation and effect of the reformed gas engine system S4 having the above configuration will be described together with the operation.

  In this reformed gas engine system S4, the ECU 56 executes the processing of the program shown in the flowchart of FIG. 10 instead of the processing of the program shown in the flowchart of FIG.

  In the processing of the program shown in the flowchart of FIG. 10, only the steps ST13 and ST19 perform processing different from the processing of the program shown in the flowchart of FIG. 3, and the other processing is shown in the flowchart of FIG. The same processing as that of the program to be executed is performed.

  That is, as described above, the ECU 56 controls the pump 74 and the condensate injection valve 76 (condensate supply device 46) to exhaust the condensate when the engine 44 is operated under the lean condition using the reformed gas as fuel. The fuel is injected to the upstream side of the three-way catalyst 72 in the passage 68, and the pump 82 and the flow rate control valve 84 (condensate recirculation device 80) are controlled to recirculate the condensate to the water tank 14 (step ST13).

When the ECU 56 determines that the liquid level L of the condensate is not higher than the level L _L provided with the lower liquid level sensor 50 (step ST18: NO), as described above, the ECU 74 and the condensing liquid are used. The liquid injection valve 76 (condensate supply device 46) is stopped, and the pump 82 and the flow rate control valve 84 (condensate reflux device 80) are stopped (step ST19).

  Thus, according to the reformed gas engine system S4 according to the fourth embodiment of the present invention, the condensate stored in the condenser 32 can be returned to the water tank 14 by the condensate reflux device 80. The condensate can be reused to produce reformed gas.

  The reformed gas engine system S4 according to the fourth embodiment of the present invention is provided with a condensate recirculation device 80 and an ECU 56 in addition to the above-described reformed gas engine system S2 according to the second embodiment of the present invention. May be configured to operate as described above.

  In the reformed gas engine system S4 according to the fourth embodiment of the present invention, the condensate stored in the condenser 32 is returned to the water tank 14 by the condensate reflux device 80. A dedicated tank may be provided in addition to the tank 14, and the condensate stored in the condenser 32 may be returned to the dedicated tank by the condensate reflux device 80.

  As mentioned above, although one Embodiment of this invention was described, this invention is not limited above, Of course, it can change and implement variously within the range which does not deviate from the main point. .

It is a figure showing the whole reformed gas engine system composition concerning a first embodiment of the present invention. It is a figure which shows the relationship between the temperature of the reforming catalyst shown by FIG. 1, and the molar concentration of the component component of the reformed gas produced | generated by this reforming catalyst. 2 is a flowchart showing the operation of the ECU shown in FIG. It is a figure which shows the whole structure of the reformed gas engine system which concerns on 2nd embodiment of this invention. 5 is a flowchart showing an operation of the ECU shown in FIG. 5 is a flowchart showing an operation of the ECU shown in FIG. It is a figure which shows the whole structure of the reformed gas engine system which concerns on 3rd embodiment of this invention. It is a flowchart which shows operation | movement of ECU shown by FIG. It is a figure which shows the whole structure of the reformed gas engine system which concerns on 4th embodiment of this invention. 10 is a flowchart showing the operation of the ECU shown in FIG.

Explanation of symbols

S1, S2, S3, S4 Reformed gas engine system 12 Fuel tank (part of raw material tank)
14 Water tank (part of raw material tank)
24 Evaporator 26 Reforming Catalyst 32 Condenser 38 Gas Storage Tank 40 Gas Injection Valve 42 Fuel Injection Valve 44 Engine 46 Condensate Supply Device 56 ECU (Control Unit)
68 Exhaust passage 70 Throttle valve 72 Three-way catalyst 80 Condensate recirculation device

Claims (7)

A raw material tank for storing reformed raw materials including water and hydrocarbon fuel;
An evaporator for evaporating the reforming raw material supplied from the raw material tank;
A reforming catalyst that generates reformed gas from the reformed raw material evaporated in the evaporator;
A condenser for separating the steam component and the specific hydrocarbon component from the reformed gas produced by the reforming catalyst, and storing the condensate containing the separated steam component and the specific hydrocarbon component;
A gas injection valve capable of adjusting the amount of the reformed gas to be injected while injecting the reformed gas from which the water vapor component and the specific hydrocarbon component are separated in the condenser into the cylinder of the engine;
A throttle valve for adjusting the amount of air supplied into the cylinder of the engine;
A three-way catalyst provided in an exhaust passage connected to the engine for purifying exhaust gas discharged from a cylinder of the engine;
A condensate supply device for supplying condensate stored in the condenser to the upstream side of the three-way catalyst in the exhaust passage;
When the amount of condensate stored in the condenser is within a predetermined range, the gas injection valve and the gas injection valve and the engine are operated such that the engine is operated under stoichiometric conditions using the reformed gas as fuel. When the reformed gas stoichiometric combustion mode for controlling the throttle valve is selected, and the amount of condensate stored in the condenser is within another predetermined amount range that is higher than the upper limit of the predetermined amount range, The gas injection valve and the throttle valve are controlled so that the engine is operated under the lean condition using the reformed gas as fuel, and the condensate stored in the condenser is upstream of the three-way catalyst in the exhaust passage. A control unit for selecting a reformed gas lean combustion mode for controlling the condensate supply device to be supplied to the side;
A reformed gas engine system. The control unit controls the condensate supply device to control the three-way catalyst in the exhaust passage so that oxygen in the exhaust gas passing through the three-way catalyst is consumed in the reformed gas lean combustion mode. Adjust the amount of condensate supplied upstream,
The reformed gas engine system according to claim 1. A fuel injection valve capable of adjusting the amount of hydrocarbon fuel to be injected while injecting hydrocarbon fuel supplied from the raw material tank into the cylinder of the engine;
A gas storage tank provided between the condenser and the gas injection valve, for storing the reformed gas from which the water vapor component and the specific hydrocarbon component are separated in the condenser;
With
When the pressure of the reformed gas stored in the gas storage tank is within a predetermined pressure range determined in advance, the control unit controls the fuel so that the engine is operated using the hydrocarbon fuel as fuel. Selecting a hydrocarbon fuel combustion mode for controlling the injection valve and the throttle valve;
The reformed gas engine system according to claim 1 or 2. When the amount of condensate stored in the condenser is within the predetermined amount range in the hydrocarbon fuel combustion mode, the control unit operates under stoichiometric conditions using the hydrocarbon fuel as fuel. And selecting a hydrocarbon fuel stoichiometric combustion mode for controlling the fuel injection valve and the throttle valve, and in the hydrocarbon fuel combustion mode, the amount of condensate stored in the condenser is the other predetermined amount. If within the range, the fuel injection valve and the throttle valve are controlled so that the engine is operated under lean conditions using the hydrocarbon fuel as fuel, and the condensate stored in the condenser is A hydrocarbon fuel lean combustion mode for controlling the condensate supply device to be supplied upstream of the three-way catalyst in the exhaust passage. To-option,
The reformed gas engine system according to claim 3. The control unit controls the condensate supply device to control the three-way catalyst in the exhaust passage so that oxygen in the exhaust gas passing through the three-way catalyst is consumed in the hydrocarbon fuel lean combustion mode. Adjusting the amount of condensate supplied upstream to the
The reformed gas engine system according to claim 4. When the pressure of the reformed gas stored in the gas storage tank is within another predetermined pressure range whose upper limit is higher than the upper limit of the predetermined pressure range, the control unit is configured to change the reformed gas stoichiometric combustion mode or the Select the reformed gas lean combustion mode,
The reformed gas engine system according to any one of claims 3 to 5. The raw material tank is
A water tank for storing water;
A fuel tank for storing hydrocarbon fuel;
Have
A condensate reflux device for refluxing the condensate stored in the condenser to the evaporator or the water tank;
The reformed gas engine system according to any one of claims 1 to 6.

Images