Engine device

Abstract

To provide an engine device capable of suppressing a use amount of a reducing agent and purifying exhaust gas while reducing the size of the device and maintaining good exhaust gas properties.SOLUTION: An engine device 1 includes an engine 2 that is driven by fuel at least including ammonia. The engine device 1 further includes: an exhaust passage 4 for causing exhaust gas discharged from the engine 2 to an air discharge direction; a selective reduction catalyst 6 provided in the exhaust passage 4 to reduce nitrogen oxide included in exhaust gas by using a reducing agent; an ammonia adsorption catalyst 7 provided in the exhaust passage 4 on the upstream side of the selective reduction catalyst 6 in the air discharge direction to adsorb ammonia included in the exhaust gas; a first bypass passage 8 connected to the exhaust passage 4 to bypass the ammonia adsorption catalyst 7; and a first path selector valve 9 provided on the upstream side of the ammonia adsorption catalyst 7 in the air discharge direction and switching whether an exhaust gas flows via the ammonia adsorption catalyst 7 or not.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to an engine device having an engine that runs on fuel containing at least ammonia. [Background technology]

[0002] Conventionally, engine devices include those equipped with engines that run on fuel containing at least ammonia, such as ammonia-only combustion engines that run on ammonia as the sole fuel, and ammonia-mixed combustion engines that run on ammonia and hydrocarbon fuels such as hydrogen and / or diesel. Exhaust gases emitted from such engines may contain unburned ammonia and nitrogen oxides (NOx), and the engine devices are required to purify and discharge the unburned ammonia and nitrogen oxides in the exhaust gases.

[0003] For example, in Patent Document 1, an exhaust purification device that purifies exhaust gas from an internal combustion engine that uses ammonia as fuel includes a catalyst that has the function of reducing nitrogen oxides and the function of oxidizing ammonia, an adsorbent arranged downstream of the catalyst and that adsorbs ammonia in the exhaust gas, an activation state detection unit that detects the activation state of the catalyst, a concentration acquisition unit that acquires the concentration of exhaust gas downstream of the adsorbent, and a control unit that controls the amount of ammonia supplied by a fuel supply unit that supplies ammonia to the internal combustion engine. When the catalyst is in an activated state, the control unit uses the exhaust gas concentration acquired by the concentration acquisition unit to control the amount of ammonia supplied so as to maintain a constant concentration of exhaust gas downstream of the adsorbent.

[0004] Furthermore, in Patent Document 2, the ammonia engine system is an ammonia engine system that includes an ammonia engine that uses ammonia as fuel, and an ammonia cracker device that includes an ammonia cracker catalyst that decomposes ammonia and generates hydrogen by decomposing the ammonia, and an ammonia oxidizer is provided between the ammonia engine and the ammonia cracker device. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Publication No. 2020-90894 [Patent Document 2] Japanese Patent Application Laid-Open No. 2010-121509 Summary of the Invention [Problem to be solved by the invention]

[0006] However, in conventional engine systems such as that described in Patent Document 1, the catalyst can purify exhaust gas by reducing nitrogen oxides and oxidizing ammonia in the exhaust gas, but it does not control the amounts or ratios of nitrogen oxides and ammonia in the exhaust gas. Therefore, it is necessary to configure the exhaust purification system based on the maximum values ​​of nitrogen oxides and ammonia expected in the exhaust gas, which may result in an increase in the capacity and size of the exhaust purification system.

[0007] Furthermore, in conventional engine devices such as those disclosed in Patent Document 2, ammonia is mixed with hydrogen and burned in order to improve the flame retardancy of ammonia, but no consideration is given to improving the deterioration of exhaust gas properties caused by the combustion or to purifying the exhaust gas.

[0008] An object of the present invention is to provide an engine device that can purify exhaust gas by reducing the amount of reducing agent used while reducing the size of the device and maintaining good exhaust gas properties. [Means for solving the problem]

[0009] In order to solve the above problems, an engine device of the present invention is an engine device equipped with an engine that is operated by fuel containing at least ammonia, and is characterized by comprising: an exhaust passage through which exhaust gas discharged from the engine flows in an exhaust direction; a selective reduction catalyst that reduces nitrogen oxides contained in the exhaust gas with a reducing agent in the exhaust passage; an ammonia adsorption catalyst that adsorbs ammonia contained in the exhaust gas in the exhaust passage upstream of the selective reduction catalyst in the exhaust direction; a first bypass passage connected to the exhaust passage so as to bypass the ammonia adsorption catalyst; and a first path switching valve that switches whether or not the flow of the exhaust gas passes through the ammonia adsorption catalyst. [Effects of the Invention]

[0010] According to the present invention, an engine device is provided that can purify exhaust gas by reducing the amount of reducing agent used while reducing the size of the device and maintaining good exhaust gas properties. [Brief explanation of the drawings]

[0011] [Figure 1] 1 is a schematic diagram illustrating an example of an engine device according to an embodiment of the present invention. [Figure 2] 1 is a schematic diagram illustrating an example of a portion of an engine in an engine device according to an embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0012] An engine apparatus 1 according to an embodiment of the present invention will be described with reference to the drawings. As shown in Fig. 1, the engine apparatus 1 includes an engine 2, an intake passage 3, and an exhaust passage 4. The engine apparatus 1 also includes a selective reduction catalyst 6, an ammonia adsorption catalyst 7, a first bypass passage 8, a first path switching valve 9, a second bypass passage 10, a second path switching valve 11, and a third path switching valve 12. The engine apparatus 1 also includes a first ammonia detection unit 14, a first nitrogen oxide detection unit 15, a second ammonia detection unit 16, a second nitrogen oxide detection unit 17, a temperature detection unit 18, and a control device 19.

[0013] In particular, in this embodiment, the engine 2 is operated by a fuel containing at least ammonia, such as an ammonia-only combustion engine that operates using ammonia as the sole fuel, or an ammonia-mixed combustion engine that operates using ammonia and a hydrocarbon fuel such as hydrogen and / or diesel. A mixture of ammonia and air is supplied to the combustion chamber 21a of each cylinder 21 of the engine 2 and combusted.

[0014] The engine 2 is, for example, a four-stroke engine, and is configured by including a plurality of cylinders 21 in a cylinder block 20 and a crankcase 22 (see FIG. 2). Although FIG. 1 illustrates four cylinders 21, the number of cylinders 21 is not limited to four. As shown in FIG. 2, each cylinder 21 is configured by a cylinder 23, a piston 24, and a cylinder head 25.

[0015] The cylinder 23 is formed, for example, in a cylindrical shape within the cylinder block 20, and the piston 24 is slidably housed within the cylinder 23. The cylinder head 25 is attached to the upper side of the cylinder 23, and a combustion chamber 21a is formed inside the cylinder 23 and the cylinder head 25. The cylinder head 25 is provided with an ignition device 26 that ignites fuel within the combustion chamber 21a.

[0016] Each cylinder 23 of the multiple cylinders 21 is connected to a crankcase 22, and a crankshaft 27 is rotatably supported by the crankcase 22. A piston 24 of each cylinder 21 is connected to the crankshaft 27 via a connecting rod 28, and the reciprocating motion of the piston 24 is converted into the rotational motion of the crankshaft 27 via the connecting rod 28.

[0017] The cylinder head 25 has an intake port 29 and an exhaust port 30 that communicate with the combustion chamber 21a of the cylinder 23, and is equipped with an intake valve 31 and an exhaust valve 32 that open and close the intake port 29 and the exhaust port 30, respectively, to the combustion chamber 21a.

[0018] The intake port 29 is connected to the intake passage 3 and introduces air supplied from the intake passage 3 into the combustion chamber 21a, while the exhaust port 30 is connected to the exhaust passage 4 and discharges exhaust gas generated in the combustion chamber 21a into the exhaust passage 4. By opening the intake valve 31, a mixture of fuel gas and air can be taken into the combustion chamber 21a via the intake port 29, while by opening the exhaust valve 32, exhaust gas generated in the combustion chamber 21a can be exhausted via the exhaust port 30.

[0019] The intake passage 3 is connected to the plurality of cylinders 21 of the engine 2 and supplies compressed and cooled air to each of the cylinders 21. A mixture of air supplied from the intake passage 3 and ammonia supplied from an ammonia tank 35 is supplied from the intake passage 3 to the combustion chamber 21a of each of the cylinders 21. For example, the intake passage 3 is connected to the engine 2 via an intake manifold 33. The intake manifold 33 has branch passages 33a branching to the plurality of cylinders 21, and each branch passage 33a is connected to a corresponding intake port 29.

[0020] A fuel supply unit 36 ​​for supplying ammonia from an ammonia tank 35 to each combustion chamber 21a is provided in the intake passage 3, the branch passage 33a, the intake port 29, or the cylinder head 25. The fuel supply unit 36 ​​is controlled by the control device 19 in terms of the amount of ammonia supplied (supply pressure), supply timing, etc. The fuel supply unit 36 ​​may be configured with a venturi mixer that mixes ammonia with the air flowing through the intake passage 3, or may be configured with an admission valve, an injector, or the like that is provided corresponding to each combustion chamber 21a and that injects ammonia.

[0021] The exhaust passage 4 is connected to the multiple cylinders 21 of the engine 2, and circulates and discharges exhaust gas generated in each cylinder 21. For example, the exhaust passage 4 is connected to the engine 2 via an exhaust manifold 34. The exhaust manifold 34 has branch passages 34a that branch out to the multiple cylinders 21, and each branch passage 34a is connected to a corresponding exhaust port 30.

[0022] The exhaust passage 4 is connected, on the downstream side in the exhaust direction, to a selective reduction catalyst 6 and an ammonia adsorption catalyst 7 for treating exhaust gas flowing through the exhaust passage 4. The selective reduction catalyst 6 and the ammonia adsorption catalyst 7 are arranged in series through the exhaust passage 4.

[0023] The selective reduction catalyst 6 is provided in the exhaust passage 4, and purifies the exhaust gas of ammonia and nitrogen oxides by selectively reducing nitrogen oxides contained in the exhaust gas flowing through the exhaust passage 4 with a reducing agent such as urea water. A reducing agent supply unit 6a that supplies a reducing agent toward the selective reduction catalyst 6 is provided in the exhaust passage 4 upstream of the selective reduction catalyst 6 in the exhaust direction. The reducing agent supply unit 6a has the supply amount of reducing agent controlled by a control device 19.

[0024] For example, the selective reduction catalyst 6 reduces ammonia and nitrogen oxides by causing them to react with each other at a ratio (proportion) of concentration or molar number of one to one, and the reducing agent supply unit 6a supplies the reducing agent under the control of the control device 19 so that the concentration or molar number of ammonia and nitrogen oxides introduced into the selective reduction catalyst 6 together with the exhaust gas becomes one to one.

[0025] The ammonia adsorption catalyst 7 is provided in the exhaust passage 4 upstream of the selective reduction catalyst 6 in the exhaust direction, and purifies the ammonia in the exhaust gas by adsorbing the ammonia contained in the exhaust gas flowing through the exhaust passage 4. In other words, the ammonia adsorption catalyst 7 adsorbs ammonia, thereby reducing the concentration and / or the number of moles of ammonia introduced into the selective reduction catalyst 6 by the exhaust gas.

[0026] For example, the ammonia adsorption catalyst 7 may be made of a material that adsorbs ammonia, such as activated carbon, zeolite, Prussian blue, MOF (a porous metal complex, or also called PCP (porous coordination polymer)), etc. Alternatively, the ammonia adsorption catalyst 7 may be made of a material that reacts with nitrogen oxides in addition to the function of adsorbing ammonia, such as Fe ion-exchanged zeolite or Cu ion-exchanged zeolite.

[0027] In addition, when ammonia is adsorbed on the ammonia adsorption catalyst 7, the ammonia adsorption catalyst 7 is configured so that, when exhaust gas is passed through the ammonia adsorption catalyst 7, the ammonia is desorbed from the ammonia adsorption catalyst 7 by wind force of the exhaust gas or reaction with nitrogen oxides. In this case, the ammonia adsorption catalyst 7 may be configured to be capable of desorbing ammonia at a predetermined desorption temperature or higher.

[0028] The first bypass passage 8 is connected to the exhaust passage 4 so as to bypass the ammonia adsorption catalyst 7. That is, the first bypass passage 8 is connected to the exhaust passage 4 on the upstream side of the ammonia adsorption catalyst 7 in the exhaust direction, and on the downstream side of the ammonia adsorption catalyst 7 and the upstream side of the selective reduction catalyst 6. The exhaust passage 4 may have a check valve or the like to prevent backflow from the first bypass passage 8 to the exhaust passage 4, upstream in the exhaust direction of the junction of the exhaust passage 4 and the outlet of the first bypass passage 8. The first bypass passage 8 may also have a check valve or the like to prevent backflow from the exhaust passage 4 to the first bypass passage 8, upstream in the exhaust direction of the junction of the exhaust passage 4 and the outlet of the first bypass passage 8.

[0029] The first path switching valve 9 is provided in the exhaust passage 4 upstream of the ammonia adsorption catalyst 7 in the exhaust direction, and switches whether or not the flow of exhaust gas passes through the ammonia adsorption catalyst 7. In other words, a main exhaust path 101 is a path through which exhaust gas emitted from the engine 2 flows only through the exhaust passage 4 and is discharged via the ammonia adsorption catalyst 7 and the selective reduction catalyst 6, and the first path switching valve 9 switches whether or not to allow exhaust gas to flow through the main exhaust path 101. The first path switching valve 9 is controlled by the control device 19 and switched between an open state and a closed state; when in the open state, it allows exhaust gas to flow through the main exhaust path 101, and when in the closed state, it does not allow exhaust gas to flow through the main exhaust path 101.

[0030] The second bypass passage 10 is connected to the exhaust passage 4 so as to bypass the ammonia adsorption catalyst 7 and the selective reduction catalyst 6. That is, the second bypass passage 10 is connected to the exhaust passage 4 on the upstream side of the ammonia adsorption catalyst 7 in the exhaust direction and on the downstream side of the selective reduction catalyst 6. The exhaust passage 4 may have a check valve or the like to prevent backflow from the second bypass passage 10 to the exhaust passage 4, upstream in the exhaust direction of the junction of the exhaust passage 4 and the outlet of the second bypass passage 10. The second bypass passage 10 may have a check valve or the like to prevent backflow from the exhaust passage 4 to the second bypass passage 10, upstream in the exhaust direction of the junction of the exhaust passage 4 and the outlet of the second bypass passage 10.

[0031] The second path switching valve 11 is provided in the first bypass passage 8 upstream of the selective reduction catalyst 6 in the exhaust direction, and switches whether or not the flow of exhaust gas passes through the selective reduction catalyst 6. In other words, the first bypass passage 102 is a route through which exhaust gas emitted from the engine 2 passes through the exhaust passage 4 and the first bypass passage 8 without passing through the ammonia adsorption catalyst 7, and is then discharged via the selective reduction catalyst 6, and the second path switching valve 11 switches whether or not to permit the exhaust gas to pass through the first bypass passage 102. The second path switching valve 11 is controlled by the control device 19 and switched between an open state and a closed state; when in the open state, it permits the exhaust gas to pass through the first bypass passage 102, and on the other hand, when in the closed state, it does not permit the exhaust gas to pass through the first bypass passage 102.

[0032] The third path switching valve 12 is provided in the second bypass passage 10, and switches whether or not exhaust gas flows, bypassing the ammonia adsorption catalyst 7 and the selective reduction catalyst 6. In other words, the second bypass passage 103 is a route through which exhaust gas emitted from the engine 2 flows through the exhaust passage 4 and the second bypass passage 10 and is discharged without passing through the ammonia adsorption catalyst 7 and the selective reduction catalyst 6, and the third path switching valve 12 switches whether or not exhaust gas is permitted to flow through the second bypass passage 103. The third path switching valve 12 is controlled by the control device 19 and switched between an open state and a closed state; when in the open state, it permits exhaust gas to flow through the second bypass passage 103, and when in the closed state, it does not permit exhaust gas to flow through the second bypass passage 103.

[0033] 1 , when the first path switching valve 9 is opened and the second path switching valve 11 and the third path switching valve 12 are closed, exhaust gas flows through a main exhaust path 101 and is discharged. When the second path switching valve 11 is opened and the first path switching valve 9 and the third path switching valve 12 are closed, exhaust gas flows through a first bypass path 102 and is discharged. When the third path switching valve 12 is opened and the first path switching valve 9 and the second path switching valve 11 are closed, exhaust gas flows through a second bypass path 103 and is discharged.

[0034] The first ammonia detection unit 14 is provided in the exhaust passage 4 upstream of the ammonia adsorption catalyst 7 in the exhaust direction, specifically upstream of the branch point between the exhaust passage 4 and the inlet of the first bypass passage 8, and detects unburned ammonia contained in the exhaust gas flowing through the exhaust passage 4. For example, the first ammonia detection unit 14 detects the emission amount and concentration of ammonia contained in the exhaust gas, and also makes it possible to calculate the number of moles of ammonia contained in the exhaust gas based on the detection result.

[0035] The first nitrogen oxide detection unit 15 is provided in the exhaust passage 4 upstream of the ammonia adsorption catalyst 7 in the exhaust direction, specifically upstream of the branch point between the exhaust passage 4 and the inlet of the first bypass passage 8, and detects nitrogen oxides contained in the exhaust gas flowing through the exhaust passage 4. For example, the first nitrogen oxide detection unit 15 detects the emission amount and concentration of nitrogen oxides contained in the exhaust gas, and is also capable of calculating the number of moles of nitrogen oxides contained in the exhaust gas based on the detection results.

[0036] 1 illustrates an example in which the first nitrogen oxide detection unit 15 is disposed upstream of the first ammonia detection unit 14 in the exhaust direction in the exhaust passage 4, but the present invention is not limited to this example, and alternatively, the first ammonia detection unit 14 may be disposed upstream of the first nitrogen oxide detection unit 15 in the exhaust direction. In this embodiment, an example is described in which the first ammonia detection unit 14 and the first nitrogen oxide detection unit 15 are configured as separate devices or sensors, but the present invention is not limited to this example, and alternatively, the first ammonia detection unit 14 and the first nitrogen oxide detection unit 15 may be configured as an integrated device or sensor.

[0037] The second ammonia detection unit 16 is provided in the exhaust passage 4 downstream in the exhaust direction of the ammonia adsorption catalyst 7 and upstream of the selective reduction catalyst 6, specifically, upstream in the exhaust direction of the junction of the exhaust passage 4 and the outlet of the first bypass passage 8, and detects unburned ammonia contained in the exhaust gas flowing through the exhaust passage 4. For example, the second ammonia detection unit 16 detects the emission amount and concentration of ammonia contained in the exhaust gas, and also makes it possible to calculate the number of moles of ammonia contained in the exhaust gas based on the detection results.

[0038] The second nitrogen oxide detection unit 17 is provided in the exhaust passage 4 downstream in the exhaust direction of the ammonia adsorption catalyst 7 and upstream of the selective reduction catalyst 6, specifically, upstream in the exhaust direction of the junction of the exhaust passage 4 and the outlet of the first bypass passage 8, and detects nitrogen oxides contained in the exhaust gas flowing through the exhaust passage 4. For example, the second nitrogen oxide detection unit 17 detects the emission amount and concentration of nitrogen oxides contained in the exhaust gas, and also makes it possible to calculate the number of moles of nitrogen oxides contained in the exhaust gas based on the detection results.

[0039] 1 illustrates an example in which the second nitrogen oxide detection unit 17 is disposed upstream of the second ammonia detection unit 16 in the exhaust direction in the exhaust passage 4, but the present invention is not limited to this example, and alternatively, the second ammonia detection unit 16 may be disposed upstream of the second nitrogen oxide detection unit 17 in the exhaust direction. In this embodiment, an example is described in which the second ammonia detection unit 16 and the second nitrogen oxide detection unit 17 are configured as separate devices or sensors, but the present invention is not limited to this example, and alternatively, the second ammonia detection unit 16 and the second nitrogen oxide detection unit 17 may be configured as an integrated device or sensor.

[0040] The temperature detection unit 18 detects the temperature of the exhaust gas discharged from the engine 2 and / or the temperature of the ammonia adsorption catalyst 7. For example, the temperature detection unit 18 is provided in the exhaust passage 4 upstream of the ammonia adsorption catalyst 7 in the exhaust direction, specifically downstream of the branch point between the exhaust passage 4 and the inlet of the first bypass passage 8, and detects the temperature of the exhaust gas introduced from the exhaust passage 4 to the ammonia adsorption catalyst 7. Alternatively, the temperature detection unit 18 is provided near the ammonia adsorption catalyst 7 or in contact with the ammonia adsorption catalyst 7, and detects the temperature of the ammonia adsorption catalyst 7.

[0041] The control device 19 is a computer such as an ECU (Engine Control Unit) that controls the operation of the engine 2, and is equipped with a CPU, ROM, RAM, etc., and is configured to control each part of the engine 2. The control device 19 may store various programs for controlling the engine 2, and control the engine 2 by reading and executing the programs.

[0042] For example, based on the detection results of the second ammonia detection unit 16 and the second nitrogen oxide detection unit 17, the control device 19 controls the reducing agent supply unit 6a and controls the supply amount of reducing agent supplied to the selective reduction catalyst 6 so that the ratio of the concentrations or molar numbers, etc. of ammonia and nitrogen oxides introduced into the selective reduction catalyst 6 together with the exhaust gas becomes a predetermined ratio (for example, one to one).

[0043] Furthermore, the control device 19 determines whether or not to pass the exhaust gas through the ammonia adsorption catalyst 7 or the selective reduction catalyst 6, based on the ratio of the concentration or number of moles, etc. of unburned ammonia and the ratio of the concentration or number of moles, etc. of nitrogen oxides in the exhaust gas emitted from the engine 2. Preferably, the control device 19 determines whether or not to pass the exhaust gas through the ammonia adsorption catalyst 7 or the selective reduction catalyst 6, based on the ratio of unburned ammonia and the ratio of nitrogen oxides, as well as the amount of ammonia adsorption on the ammonia adsorption catalyst 7. Based on the result of this determination, the control device 19 controls the operation of the first path switching valve 9, and preferably controls the operation of the second path switching valve 11 and the third path switching valve 12 in addition to the first path switching valve 9, thereby controlling the flow of the exhaust gas.

[0044] Here, the control device 19 acquires the ratio of unburned ammonia and the ratio of nitrogen oxides in the exhaust gas upstream of the ammonia adsorption catalyst 7 in the exhaust passage 4, specifically, upstream of the branch point between the exhaust passage 4 and the inlet of the first bypass passage 8. For example, the control device 19 acquires the ratio of ammonia and the ratio of nitrogen oxides based on the detection results of the first ammonia detection unit 14 and the first nitrogen oxide detection unit 15.

[0045] Furthermore, the control device 19 calculates or estimates the amount of ammonia adsorption on the ammonia adsorption catalyst 7 based on the temperature of the exhaust gas and / or the temperature of the ammonia adsorption catalyst 7. For example, the control device 19 monitors the concentration of unburned ammonia and the concentration of nitrogen oxides per unit time in the exhaust gas introduced into the ammonia adsorption catalyst 7 based on the detection result of the first ammonia detection unit 14 and the detection result of the first nitrogen oxide detection unit 15. The control device 19 acquires the amount of ammonia adsorption by using a model that calculates the amount of ammonia adsorption on the ammonia adsorption catalyst 7 based on the temperature of the exhaust gas and / or the temperature of the ammonia adsorption catalyst 7, the concentration of ammonia, and the concentration of nitrogen oxides.

[0046] Furthermore, the control device 19 controls the route through which the exhaust gas flows to be switched to one of the main exhaust route 101, the first bypass route 102, and the second bypass route 103, based on the ammonia ratio and the nitrogen oxide ratio detected by the first ammonia detection unit 14 and the first nitrogen oxide detection unit 15. Preferably, the control device 19 controls the operation of the first route switching valve 9 based on the ammonia adsorption amount of the ammonia adsorption catalyst 7 in addition to the ammonia ratio and the nitrogen oxide ratio, and preferably switches the route through which the exhaust gas flows by controlling the operation of the second route switching valve 11 and the third route switching valve 12 in addition to the first route switching valve 9.

[0047] For example, when the ratio of ammonia in the exhaust gas is higher than the ratio of nitrogen oxides, or when the ratio of nitrogen oxides in the exhaust gas is higher than the ratio of ammonia and the amount of ammonia adsorbed by the ammonia adsorption catalyst 7 is greater than a predetermined adsorption amount threshold, the control device 19 opens the first path switching valve 9 and closes the second path switching valve 11 and the third path switching valve 12 to switch to the main discharge path 101, thereby causing the exhaust gas to pass through the ammonia adsorption catalyst 7 and the selective reduction catalyst 6 and be discharged.

[0048] Furthermore, when the ratio of nitrogen oxides in the exhaust gas is higher than the ratio of ammonia and the amount of ammonia adsorbed by the ammonia adsorption catalyst 7 is smaller than a predetermined adsorption amount threshold, the control device 19 opens the second path switching valve 11 and closes the first path switching valve 9 and the third path switching valve 12 to switch to the first bypass path 102, thereby causing the exhaust gas to pass through the selective reduction catalyst 6 without passing through the ammonia adsorption catalyst 7 and being discharged.

[0049] Furthermore, regardless of the ratio of nitrogen oxides and the ratio of ammonia in the exhaust gas, when an abnormality occurs in the operating state of the engine 2 or the selective reduction catalyst 6, the control device 19 opens the third path switching valve 12 and closes the first path switching valve 9 and the second path switching valve 11 to switch to the second bypass path 103, thereby discharging the exhaust gas without passing through the ammonia adsorption catalyst 7 and the selective reduction catalyst 6.

[0050] For example, the control device 19 may determine that an abnormality has occurred in the operating state of the engine 2 when parameters (for example, load, fuel injection pressure, fuel injection timing, excess air ratio, etc.) set for supplying ammonia to the engine 2 fall outside the range of a safe region. When a sensor that detects ammonia or nitrogen oxides downstream of the selective reduction catalyst 6 in the exhaust direction detects a predetermined amount or more of ammonia or nitrogen oxides, it may be determined that an abnormality has occurred in the selective reduction catalyst 6.

[0051] As described above, according to this embodiment, the engine device 1 is an engine device 1 including an engine 2 that is operated by fuel containing at least ammonia, and includes an exhaust passage 4 through which exhaust gas discharged from the engine 2 flows in an exhaust direction, a selective reduction catalyst 6 in the exhaust passage 4 that reduces nitrogen oxides contained in the exhaust gas with a reducing agent, an ammonia adsorption catalyst 7 in the exhaust passage 4 upstream of the selective reduction catalyst 6 in the exhaust direction and that adsorbs ammonia contained in the exhaust gas, a first bypass passage 8 connected to the exhaust passage 4 so as to bypass the ammonia adsorption catalyst 7, and a first path switching valve 9 that switches whether the flow of exhaust gas passes through the ammonia adsorption catalyst 7 or not. For example, the first path switching valve 9 is provided upstream of the ammonia adsorption catalyst 7 in the exhaust direction.

[0052] As a result, the engine system 1 can purify exhaust gas by reducing the amount of reducing agent used while maintaining good exhaust gas properties and achieving a compact system. For example, the engine system 1 adsorbs excess ammonia in the exhaust gas with the ammonia adsorption catalyst 7, thereby circulating the exhaust gas with reduced ammonia content downstream, and can introduce and purify exhaust gas with an appropriate ammonia / nitrogen oxide ratio with the selective reduction catalyst 6 downstream.

[0053] Furthermore, the engine device 1 does not oxidize and remove the ammonia adsorbed by the ammonia adsorption catalyst 7, but instead blows it off with the exhaust gas and circulates it downstream to serve as a purification source for nitrogen oxides, thereby making it possible to suppress the amount of reducing agent required to be supplied to the selective reduction catalyst 6, thereby saving the reducing agent and improving the purification efficiency of ammonia and nitrogen oxides. Therefore, it is not necessary to treat all of the ammonia in the exhaust gas with the ammonia adsorption catalyst 7, and the ammonia adsorption catalyst 7 can be made smaller.

[0054] Furthermore, the engine device 1 can reduce the use of the ammonia adsorption catalyst 7 and extend its lifespan by discharging exhaust gases bypassing the ammonia adsorption catalyst 7 through the first bypass passage 8, and the selective reduction catalyst 6 downstream of the ammonia adsorption catalyst 7 can purify ammonia and nitrogen oxides by supplying a reducing agent so that the ratio of ammonia / nitrogen oxides introduced along with the exhaust gas becomes appropriate.

[0055] In this way, in order to purify the ammonia and nitrogen oxides in the exhaust gas at an appropriate ratio with the selective reduction catalyst 6, the engine device 1 not only controls the combustion of the engine 2 and the supply of the reducing agent, but also uses the ammonia adsorption catalyst 7 in some cases, thereby making it possible to make the ratio of ammonia and nitrogen oxides introduced into the selective reduction catalyst 6 appropriate. Therefore, the engine device 1 does not need to control the ratio of ammonia and nitrogen oxides in the exhaust gas emitted from the engine 2 within a certain range, just by combustion in the engine 2, and the engine 2 can be operated with emphasis on fuel efficiency.

[0056] Moreover, according to the present embodiment, the engine device 1 further includes a second bypass passage 10 connected to the exhaust passage 4 so as to bypass the ammonia adsorption catalyst 7 and the selective reduction catalyst 6, and a second path switching valve 11 that switches whether or not the flow of exhaust gas passes through the selective reduction catalyst 6. For example, the second path switching valve 11 is provided upstream of the selective reduction catalyst 6 in the exhaust direction.

[0057] As a result, the engine device 1 can reduce use of the ammonia adsorption catalyst 7 and the selective reduction catalyst 6 and extend their lifespans by discharging exhaust gas while bypassing the ammonia adsorption catalyst 7 and the selective reduction catalyst 6 via the second bypass passage 10. Furthermore, in the event of an abnormality in the engine 2 (abnormality in exhaust gas) or an abnormality in the ammonia adsorption catalyst 7 or the selective reduction catalyst 6, damage to the ammonia adsorption catalyst 7 or the selective reduction catalyst 6 due to the introduction of exhaust gas can be suppressed.

[0058] Furthermore, according to the present embodiment, the engine device 1 further includes a first ammonia detection unit 14 that detects ammonia contained in the exhaust gas and a first nitrogen oxide detection unit 15 that detects nitrogen oxides contained in the exhaust gas, both of which are located in the exhaust passage 4 upstream of the ammonia adsorption catalyst 7 in the exhaust direction, and controls the operation of the first path switching valve 9 based on the detection results of the first ammonia detection unit 14 and the first nitrogen oxide detection unit 15.

[0059] As a result, the engine device 1 can selectively switch the path through which the exhaust gas flows with a simple configuration that uses the first ammonia detection section 14, the first nitrogen oxide detection section 15, and the first path switching valve 9.

[0060] Moreover, according to the present embodiment, the engine device 1 further includes a second ammonia detection unit 16 that detects ammonia contained in the exhaust gas, and a second nitrogen oxide detection unit 17 that detects nitrogen oxides contained in the exhaust gas, in the exhaust passage 4 downstream of the ammonia adsorption catalyst 7 and upstream of the selective reduction catalyst 6 in the exhaust direction.

[0061] As a result, the engine device 1 can determine the supply amount of reducing agent to be supplied to the selective reduction catalyst 6 with a simple configuration that uses the second ammonia detection section 16 and the second nitrogen oxide detection section 17.

[0062] Moreover, according to the present embodiment, the engine device 1 further includes a control device 19 that controls the operation of the first path switching valve 9, and a temperature detection unit 18 that detects the temperature of the exhaust gas and / or the temperature of the ammonia adsorption catalyst 7, and the control device 19 calculates or estimates the amount of ammonia adsorption on the ammonia adsorption catalyst 7 based on the detection results of the first ammonia detection unit 14, the first nitrogen oxide detection unit 15, and the temperature detection unit 18, and controls the operation of the first path switching valve 9 based on the amount of ammonia adsorption.

[0063] As a result, the engine device 1 can appropriately determine and selectively switch the exhaust gas flow path by taking into consideration the amount of ammonia adsorbed by the ammonia adsorption catalyst 7.

[0064] Furthermore, according to the present embodiment, when the ratio of ammonia in the exhaust gas is higher than the ratio of nitrogen oxides, or when the ratio of nitrogen oxides in the exhaust gas is higher than the ratio of ammonia and the ammonia adsorption amount of the ammonia adsorption catalyst 7 is higher than a predetermined adsorption amount threshold, the engine apparatus 1 discharges the exhaust gas by passing it through the ammonia adsorption catalyst 7 and the selective reduction catalyst 6. Furthermore, when the ratio of nitrogen oxides in the exhaust gas is higher than the ratio of ammonia and the ammonia adsorption amount of the ammonia adsorption catalyst 7 is lower than a predetermined adsorption amount threshold, the engine apparatus 1 discharges the exhaust gas by passing it through the selective reduction catalyst 6 without passing it through the ammonia adsorption catalyst 7. Furthermore, regardless of the ratio of nitrogen oxides and the ratio of ammonia in the exhaust gas, when an abnormality occurs in the operating state of the engine 2 or the selective reduction catalyst 6, the engine apparatus 1 discharges the exhaust gas without passing it through the ammonia adsorption catalyst 7 and the selective reduction catalyst 6.

[0065] As a result, the engine device 1 can more appropriately determine and selectively switch the route through which the exhaust gas flows by taking into consideration the ratio of ammonia and the ratio of nitrogen oxides in the exhaust gas and the amount of ammonia adsorption by the ammonia adsorption catalyst 7.

[0066] Although FIG. 1 illustrates an example in which the first path switching valve 9 is provided in the exhaust passage 4 downstream in the exhaust direction of the branch point between the exhaust passage 4 and the inlet of the first bypass passage 8, the present invention is not limited to this example. Alternatively, the first path switching valve 9 may be provided at the branch point between the exhaust passage 4 and the inlet of the first bypass passage 8.

[0067] Furthermore, FIG. 1 illustrates an example in which the second bypass passage 10 is connected to the first bypass passage 8 downstream in the exhaust direction of the branch point between the exhaust passage 4 and the inlet of the first bypass passage 8, but the present invention is not limited to this example. The second bypass passage 10 may be connected to the exhaust passage 4 at the branch point between the exhaust passage 4 and the inlet of the first bypass passage 8, or may be connected to the exhaust passage 4 upstream in the exhaust direction of the branch point between the exhaust passage 4 and the inlet of the first bypass passage 8.

[0068] 1 illustrates an example in which the second path switching valve 11 is provided in the first bypass passage 8 downstream in the exhaust direction of the branch point between the inlets of the first bypass passage 8 and the second bypass passage 10, but the present invention is not limited to this example. Alternatively, the second path switching valve 11 may be provided at the branch point between the inlets of the first bypass passage 8 and the second bypass passage 10. In this case, the second path switching valve 11 may be configured to prevent exhaust gas from flowing into the first bypass passage 8 and the second bypass passage 10, or to select either the first bypass passage 8 or the second bypass passage 10 into which the exhaust gas will flow. In this configuration, the third path switching valve 12 may be omitted.

[0069] In the above-described embodiment, an example has been described in which the control device 19 acquires the ratio (for example, concentration or number of moles) of ammonia and nitrogen oxides emitted from the engine 2 based on the detection result of the first ammonia detection unit 14 and the detection result of the first nitrogen oxide detection unit 15 in order to determine whether or not to pass the exhaust gas through the ammonia adsorption catalyst 7 or the selective reduction catalyst 6, but the present invention is not limited to this example.

[0070] In another example, the engine device 1 detects or measures the ratios (proportions) and emissions of ammonia and nitrogen oxides emitted when the engine 2 is operated under various operating conditions (such as engine speed and load), and the control device 19 pre-stores data correlating each operating condition with the ratios and / or emissions of ammonia and nitrogen oxides corresponding to each operating condition as exhaust gas information. The engine device 1 may acquire exhaust gas information by test-operating the engine 2, and / or may acquire and store exhaust gas information obtained when the engine 2 is actually operated. The control device 19 then acquires the operating conditions when the engine 2 is operated, and acquires ratio data (proportion data) and / or emission data of ammonia and nitrogen oxides corresponding to the operating conditions based on the operating conditions and the pre-stored exhaust gas information.

[0071] In this case, similar to the above-described embodiment, the control device 19 controls the operation of the first path switching valve 9 based on the acquired ratio data and / or emission amount data of ammonia and nitrogen oxides, and preferably controls the operation of the second path switching valve 11 and the third path switching valve 12 in addition to the first path switching valve 9, thereby controlling the flow of exhaust gas.

[0072] As a result, the engine device 1 pre-stores exhaust gas information indicating the relationship between the operating conditions of the engine 2 and the ratio and / or emission amount of ammonia and nitrogen oxides in the exhaust gas, thereby eliminating the need for the first ammonia detection unit 14 and the first nitrogen oxide detection unit 15 and simplifying the configuration.

[0073] Furthermore, in the above-described embodiment, an example has been described in which the control device 19 calculates the amount of ammonia adsorption on the ammonia adsorption catalyst 7 based on the temperature of the exhaust gas detected by the temperature detection unit 18 or the temperature of the ammonia adsorption catalyst 7, the concentration of ammonia detected by the first ammonia detection unit 14, and the concentration of nitrogen oxides detected by the first nitrogen oxide detection unit 15, in order to determine whether or not to pass the exhaust gas through the ammonia adsorption catalyst 7 or the selective reduction catalyst 6, but the present invention is not limited to this example.

[0074] In another example, the control device 19 acquires ratio data (proportion data) and / or emission amount data of ammonia and nitrogen oxides corresponding to the operating conditions when the engine 2 is operated based on pre-stored exhaust gas information, and calculates the ammonia concentration and the nitrogen oxide concentration based on the acquired ratio data and / or emission data of ammonia and nitrogen oxides. Then, the control device 19 calculates the ammonia adsorption amount of the ammonia adsorption catalyst 7 based on the temperature of the exhaust gas detected by the temperature detection unit 18 or the temperature of the ammonia adsorption catalyst 7 and the ammonia concentration and the nitrogen oxide concentration calculated based on the exhaust gas information.

[0075] In this case, similarly to the above-described embodiment, the control device 19 controls the operation of the first path switching valve 9 based on the ammonia adsorption amount of the ammonia adsorption catalyst 7 calculated based on the exhaust gas information, in addition to the ammonia ratio and nitrogen oxide ratio calculated based on the exhaust gas information, and preferably controls the operation of the second path switching valve 11 and the third path switching valve 12 in addition to the first path switching valve 9, thereby controlling the flow of exhaust gas.

[0076] As a result, by utilizing the exhaust gas information, the engine device 1 not only omits the first ammonia detection section 14 and the first nitrogen oxide detection section 15 to simplify the configuration, but also calculates the amount of ammonia adsorption by the ammonia adsorption catalyst 7, and can appropriately determine and selectively switch the route for circulating the exhaust gas based on the amount of ammonia adsorption.

[0077] In the above embodiment, an example has been described in which, when the ratio of nitrogen oxides in the exhaust gas is higher than the ratio of ammonia, the control device 19 switches to the main exhaust path 101 if the amount of ammonia adsorption on the ammonia adsorption catalyst 7 is larger than a predetermined adsorption amount threshold, and on the other hand, switches to the first bypass path 102 if the amount of ammonia adsorption on the ammonia adsorption catalyst 7 is smaller than the predetermined adsorption amount threshold, but the present invention is not limited to this example.

[0078] In another example, when the ratio of nitrogen oxides in the exhaust gas is higher than the ratio of ammonia, the control device 19 may determine the ammonia adsorption amount of the ammonia adsorption catalyst 7 using multiple thresholds and switch the route through which the exhaust gas flows in stages. For example, the control device 19 may preset a first adsorption amount threshold and a second adsorption amount threshold that is smaller than the first adsorption amount threshold, and control the route to be used for exhaust gas flow in a stepwise manner. When the ammonia adsorption amount is greater than the first adsorption amount threshold, the control device 19 may switch to the main discharge route 101. When the ammonia adsorption amount is equal to or less than the first adsorption amount threshold and greater than the second adsorption amount threshold, the control device 19 may switch to the first bypass route 102 so that the exhaust gas flows through both the main discharge route 101 and the first bypass route 102. When both the main discharge route 101 and the first bypass route 102 are used, the control device 19 may adjust the flow rates of the main discharge route 101 and the first bypass route 102 using the first route switching valve 9 and the second route switching valve 11 so as not to cause a pressure loss.

[0079] Furthermore, the present invention can be modified as appropriate within the scope that does not contradict the gist or idea of ​​the invention that can be read from the claims and the entire specification, and engine devices that involve such modifications are also included in the technical idea of ​​the present invention.

[0080] [Appendix to the invention] The following is a summary of the invention extracted from the above-described embodiment. Note that the configurations and processing functions described in the following supplementary notes can be selected and combined as desired.

[0081] <Appendix 1> An engine device including an engine that operates on fuel containing at least ammonia, an exhaust passage through which exhaust gas discharged from the engine flows in an exhaust direction; a selective reduction catalyst in the exhaust passage that reduces nitrogen oxides contained in the exhaust gas with a reducing agent; an ammonia adsorption catalyst that adsorbs ammonia contained in the exhaust gas, located in the exhaust passage upstream of the selective reduction catalyst in the exhaust direction; a first bypass passage connected to the exhaust passage so as to bypass the ammonia adsorption catalyst; a first path switching valve that switches whether the flow of the exhaust gas passes through the ammonia adsorption catalyst; An engine device comprising:

[0082] <Appendix 2> 2. The engine device according to claim 1, wherein the first path switching valve is provided upstream of the ammonia adsorption catalyst in the exhaust direction.

[0083] <Appendix 3> a second bypass passage connected to the exhaust passage so as to bypass the ammonia adsorption catalyst and the selective reduction catalyst; a second path switching valve that switches whether or not the flow of the exhaust gas passes through the selective reduction catalyst; 2. The engine device according to claim 1, further comprising:

[0084] <Appendix 4> 4. The engine device according to claim 3, wherein the second path switching valve is provided upstream of the selective reduction catalyst in the exhaust direction.

[0085] <Appendix 5> a first ammonia detection unit that is provided in the exhaust passage upstream of the ammonia adsorption catalyst in the exhaust direction and that detects ammonia contained in the exhaust gas; and a first nitrogen oxide detection unit that detects nitrogen oxides contained in the exhaust gas, 5. The engine device according to any one of claims 1 to 4, wherein the operation of the first path switching valve is controlled based on the detection results of the first ammonia detection section and the first nitrogen oxide detection section.

[0086] <Appendix 6> 6. The engine device according to claim 5, further comprising: a second ammonia detection unit that detects ammonia contained in the exhaust gas, and a second nitrogen oxide detection unit that detects nitrogen oxides contained in the exhaust gas, located in the exhaust passage downstream of the ammonia adsorption catalyst and upstream of the selective reduction catalyst in the exhaust direction.

[0087] <Appendix 7> a control device that controls the operation of the first path switching valve, The engine device according to any one of appendices 1 to 6, wherein the control device controls the operation of the first path switching valve based on ratio data and / or emission data of ammonia and nitrogen oxides contained in the exhaust gas under operating conditions of the engine.

[0088] <Appendix 8> a control device that controls the operation of the first path switching valve; a temperature detection unit that detects the temperature of the exhaust gas or the temperature of the ammonia adsorption catalyst, 7. The engine device according to claim 5, wherein the control device calculates or estimates an ammonia adsorption amount of the ammonia adsorption catalyst based on detection results of the first ammonia detection unit, the first nitrogen oxide detection unit, and the temperature detection unit, and controls operation of the first path switching valve based on the ammonia adsorption amount.

[0089] <Appendix 9> a temperature detection unit that detects the temperature of the exhaust gas or the temperature of the ammonia adsorption catalyst, 8. The engine device according to claim 7, wherein the control device calculates or estimates an ammonia adsorption amount of the ammonia adsorption catalyst based on the ratio data and / or the emission data and a detection result of the temperature detection unit, and controls operation of the first path switching valve based on the ammonia adsorption amount.

[0090] <Appendix 10> When a ratio of ammonia in the exhaust gas is higher than a ratio of nitrogen oxides, or when a ratio of nitrogen oxides in the exhaust gas is higher than a ratio of ammonia and an amount of ammonia adsorbed by the ammonia adsorption catalyst is larger than a predetermined adsorption amount threshold, the exhaust gas is discharged through the ammonia adsorption catalyst and the selective reduction catalyst, 10. The engine device according to any one of appendices 1 to 9, wherein, when a ratio of nitrogen oxides in the exhaust gas is higher than a ratio of ammonia and an amount of ammonia adsorbed by the ammonia adsorption catalyst is less than a predetermined adsorption amount threshold, the exhaust gas is discharged through the selective reduction catalyst without passing through the ammonia adsorption catalyst.

[0091] <Appendix 11> Regardless of the ratio of nitrogen oxides and the ratio of ammonia in the exhaust gas, when an abnormality occurs in the operating state of the engine or the selective reduction catalyst, the exhaust gas is discharged without passing through the ammonia adsorption catalyst and the selective reduction catalyst. 11. The engine device according to any one of claims 1 to 10, [Explanation of symbols]

[0092] 1 Engine equipment 2 engines 3 Intake passage 4 Exhaust passage 6. Selective reduction catalyst 6a Reducing agent supply unit 7. Ammonia adsorption catalyst 8. First Bypass Passage 9 First path switching valve 10 Second Bypass Passage 11 Second path switching valve 12 Third path switching valve 14 First ammonia detection unit 15 First nitrogen oxide detector 16 Second ammonia detection unit 17 Second nitrogen oxide detector 18 Temperature detection unit 19 Control device 20 Cylinder block 21 cylinders 21a Combustion chamber 22 Crankcase 23 cylinders 24 pistons 25 cylinder head 26 Ignition system 27 crankshaft 28 Connecting rod 29 Intake port 30 Exhaust port 31 Intake valve 32 Exhaust valve 33 Intake manifold 33a Branch channel 34 Exhaust manifold 34a Branch channel 35 Ammonia Tank 36 Fuel supply section 101 Main discharge route 102 First Bypass Route 103 Second Bypass Route

Claims

1. An engine device including an engine that operates on fuel containing at least ammonia, an exhaust passage through which exhaust gas discharged from the engine flows in an exhaust direction; a selective reduction catalyst in the exhaust passage that reduces nitrogen oxides contained in the exhaust gas with a reducing agent; an ammonia adsorption catalyst that adsorbs ammonia contained in the exhaust gas, located in the exhaust passage upstream of the selective reduction catalyst in the exhaust direction; a first bypass passage connected to the exhaust passage so as to bypass the ammonia adsorption catalyst; a first path switching valve that switches whether the flow of the exhaust gas passes through the ammonia adsorption catalyst; An engine device comprising:

2. 2. The engine apparatus according to claim 1, wherein the first path switching valve is provided upstream of the ammonia adsorption catalyst in the exhaust direction.

3. a second bypass passage connected to the exhaust passage so as to bypass the ammonia adsorption catalyst and the selective reduction catalyst; a second path switching valve that switches whether or not the flow of the exhaust gas passes through the selective reduction catalyst; The engine system according to claim 1, further comprising:

4. 4. The engine apparatus according to claim 3, wherein the second path switching valve is provided upstream of the selective reduction catalyst in the exhaust direction.

5. a first ammonia detection unit that detects ammonia contained in the exhaust gas, and a first nitrogen oxide detection unit that detects nitrogen oxides contained in the exhaust gas, the first ammonia detection unit being disposed in the exhaust passage upstream of the ammonia adsorption catalyst in the exhaust direction; 2. The engine device according to claim 1, wherein the operation of the first path switching valve is controlled based on the detection results of the first ammonia detection section and the first nitrogen oxide detection section.

6. 6. The engine device according to claim 5, further comprising: a second ammonia detection unit that detects ammonia contained in the exhaust gas; and a second nitrogen oxide detection unit that detects nitrogen oxides contained in the exhaust gas, located in the exhaust passage downstream of the ammonia adsorption catalyst and upstream of the selective reduction catalyst in the exhaust direction.

7. a control device that controls the operation of the first path switching valve, 2. The engine device according to claim 1, wherein the control device controls the operation of the first path switching valve based on data on proportions and / or emission amounts of ammonia and nitrogen oxides contained in the exhaust gas under operating conditions of the engine.

8. a control device that controls the operation of the first path switching valve; a temperature detection unit that detects the temperature of the exhaust gas or the temperature of the ammonia adsorption catalyst, 6. The engine device according to claim 5, wherein the control device calculates or estimates an ammonia adsorption amount of the ammonia adsorption catalyst based on detection results of the first ammonia detection unit, the first nitrogen oxide detection unit, and the temperature detection unit, and controls operation of the first path switching valve based on the ammonia adsorption amount.

9. a temperature detection unit that detects the temperature of the exhaust gas or the temperature of the ammonia adsorption catalyst, 8. The engine device according to claim 7, wherein the control device calculates or estimates an ammonia adsorption amount of the ammonia adsorption catalyst based on the ratio data and / or the emission data and a detection result of the temperature detection unit, and controls the operation of the first path switching valve based on the ammonia adsorption amount.

10. When a ratio of ammonia in the exhaust gas is higher than a ratio of nitrogen oxides, or when a ratio of nitrogen oxides in the exhaust gas is higher than a ratio of ammonia and an amount of ammonia adsorbed by the ammonia adsorption catalyst is larger than a predetermined adsorption amount threshold, the exhaust gas is discharged through the ammonia adsorption catalyst and the selective reduction catalyst, 2. The engine device according to claim 1, wherein, when a ratio of nitrogen oxides in the exhaust gas is higher than a ratio of ammonia, and an amount of ammonia adsorbed by the ammonia adsorption catalyst is smaller than a predetermined adsorption amount threshold, the exhaust gas is discharged through the selective reduction catalyst without passing through the ammonia adsorption catalyst.

11. 2. The engine device according to claim 1, wherein, regardless of the ratio of nitrogen oxides and the ratio of ammonia in the exhaust gas, when an abnormality occurs in the operating state of the engine or in the selective reduction catalyst, the exhaust gas is discharged without passing through the ammonia adsorption catalyst and the selective reduction catalyst.

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