Engine device

Abstract

The invention provides an engine device which can realize miniaturization of the device and can maintain good exhaust gas properties and suppress the usage amount of a reducing agent to purify exhaust gas. An engine device (1) is provided with an engine (2) that operates using a fuel containing at least ammonia, and is provided with: an exhaust passage (4) through which exhaust gas discharged from the engine flows in the exhaust direction; a selective reduction catalyst (6) that is provided in the exhaust passage and that reduces nitrogen oxides contained in the exhaust gas by means of a reducing agent; an ammonia adsorption catalyst (7) that is provided in the exhaust passage upstream of the selective reduction catalyst in the exhaust direction and adsorbs ammonia contained in the exhaust gas; a first bypass passage (8) connected to the exhaust passage so as to bypass the ammonia adsorption catalyst; and a first path switching valve (9) that is provided upstream of the ammonia adsorption catalyst in the exhaust direction and that switches whether or not to circulate the exhaust gas via the ammonia adsorption catalyst.

Description

Technical Field

[0001] The present invention relates to an engine device including an engine that is operated using fuel containing at least ammonia. Background Art

[0002] Conventional engine systems include ammonia-only engines that operate on ammonia as the sole fuel, and ammonia-co-fueled engines that operate on ammonia and hydrogen and / or hydrocarbon fuels such as light oil. Exhaust gas emitted from these engines sometimes contains unburned ammonia and nitrogen oxides (NOx), and there are requirements for purifying and discharging these unburned ammonia and NOx from the exhaust gas.

[0003] For example, Patent Document 1 discloses an exhaust gas purification device for purifying exhaust gas from an internal combustion engine using ammonia as fuel, comprising: a catalyst having a function of reducing nitrogen oxides and a function of oxidizing ammonia; an adsorbent disposed downstream of the catalyst and adsorbing ammonia in the exhaust gas; an activity state detection unit that detects the activity state of the catalyst; a concentration acquisition unit that acquires the concentration of the exhaust gas downstream of the adsorbent; and a control unit that controls the amount of ammonia supplied to a fuel supply unit of the internal combustion engine. When the catalyst is active, the control unit uses the exhaust gas concentration acquired by the concentration acquisition unit to control the amount of ammonia supplied so that the concentration of the exhaust gas downstream of the adsorbent is maintained constant.

[0004] In Patent Document 2, an ammonia engine system includes an ammonia engine that uses ammonia as fuel, and an ammonia cracker that includes an ammonia cracking catalyst that decomposes ammonia and generates hydrogen by decomposing the ammonia, with an ammonia oxidizer provided between the ammonia engine and the ammonia cracker.

[0005] Prior art literature

[0006] Patent Literature

[0007] Patent Document 1: Japanese Patent Application Laid-Open No. 2020-90894

[0008] Patent Document 2: Japanese Patent Application Laid-Open No. 2010-121509 Summary of the Invention

[0009] However, while conventional engine systems such as those described in Patent Document 1 can purify exhaust gas by reducing nitrogen oxides and oxidizing ammonia using a catalyst, they do not control the amount or ratio of nitrogen oxides and ammonia in the exhaust gas. Consequently, the exhaust purification system must be constructed based on the maximum values ​​of nitrogen oxides and ammonia expected for the exhaust gas, potentially increasing the capacity and size of the exhaust purification system.

[0010] Furthermore, in conventional engine devices such as Patent Document 2, ammonia and hydrogen are mixed and burned to improve the flame retardancy of ammonia, but no consideration is given to improving the deterioration of exhaust gas properties generated during the combustion and purifying the exhaust gas.

[0011] An object of the present invention is to provide an engine device that can achieve miniaturization of the device and can purify the exhaust gas while maintaining good exhaust gas properties and suppressing the amount of reducing agent used.

[0012] In order to solve the above-mentioned problems, the engine device of the present invention includes an engine that operates using a fuel containing at least ammonia, and is characterized in that the engine device includes: an exhaust passage that allows the exhaust gas discharged from the engine to flow in the exhaust direction; a selective reduction catalyst that reduces nitrogen oxides contained in the exhaust gas using a reducing agent in the exhaust passage; an ammonia adsorption catalyst that is located more upstream than the selective reduction catalyst in the exhaust direction and adsorbs ammonia contained in the exhaust gas in the exhaust passage; a first bypass passage that is connected to the exhaust passage in a manner that bypasses the ammonia adsorption catalyst; and a first path switching valve that switches whether the exhaust gas is allowed to flow through the ammonia adsorption catalyst.

[0013] Effects of the Invention

[0014] According to the present invention, there is provided an engine device capable of achieving miniaturization of the device and purifying the exhaust gas while maintaining good exhaust gas properties and suppressing the amount of reducing agent used. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 This is a schematic diagram showing an example of an engine device according to an embodiment of the present invention.

[0016] Figure 2 This is a schematic diagram showing an example of a portion of an engine in an engine device according to an embodiment of the present invention.

[0017] Description of Reference Numerals

[0018] 1…Engine device; 2…Engine; 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 detector; 15…First nitrogen oxide detector; 16…Second ammonia detector; 17…Second nitrogen oxide detector; 18…Temperature detector; 19…Control device; 20…Gas Cylinder block; 21…cylinder; 21a…combustion chamber; 22…crankcase; 23…cylinder block; 24…piston; 25…cylinder head; 26…ignition device; 27…crankshaft; 28…connecting rod; 29…intake port; 30…exhaust port; 31…intake valve; 32…exhaust valve; 33…intake manifold; 33a…branch flow path; 34…exhaust manifold; 34a…branch flow path; 35…ammonia container; 36…fuel supply unit; 101…main exhaust path; 102…first bypass path; 103…second bypass path. DETAILED DESCRIPTION

[0019] An engine device 1 according to an embodiment of the present invention will be described with reference to the accompanying drawings. Figure 1 As shown, the engine device 1 includes an engine 2, an intake passage 3, and an exhaust passage 4. Furthermore, the engine device 1 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. Furthermore, the engine device 1 includes a first ammonia detector 14, a first nitrogen oxide detector 15, a second ammonia detector 16, a second nitrogen oxide detector 17, a temperature detector 18, and a control device 19.

[0020] In this embodiment, the engine 2 is configured to operate using a fuel containing at least ammonia, such as an ammonia-only combustion engine that operates using ammonia as the sole fuel, or an ammonia-co-combustion engine that operates using ammonia and a hydrocarbon fuel such as hydrogen and / or light oil. A mixture of ammonia and air is supplied to the combustion chamber 21a of each cylinder 21 of the engine 2 and combusted.

[0021] The engine 2 is, for example, a 4-stroke engine, and is configured such that a cylinder block 20 includes a plurality of cylinders 21 and a crankcase 22 (see Figure 2 ).exist Figure 1 In FIG, four cylinders 21 are shown, but the number of cylinders 21 is not limited to four. Figure 2 As shown, the cylinder 21 is composed of a cylinder body 23 , a piston 24 and a cylinder head 25 .

[0022] The cylinder 23 is formed into a cylindrical shape, for example, within the cylinder block 20, and the piston 24 is slidably housed within the cylinder 23. A cylinder head 25 is mounted on the upper side of the cylinder 23, and a combustion chamber 21a is formed inside the cylinder 23 and the cylinder head 25. An ignition device 26 for igniting the fuel in the combustion chamber 21a is provided on the cylinder head 25.

[0023] Each cylinder block 23 of the plurality of cylinders 21 is connected to a crankcase 22, and a crankshaft 27 is rotatably supported by the crankcase 22. The 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 rotational motion of the crankshaft 27 via the connecting rod 28.

[0024] The cylinder head 25 has an intake port 29 and an exhaust port 30 communicating with the combustion chamber 21 a of the cylinder block 23 , and includes an intake valve 31 and an exhaust valve 32 for opening and closing the intake port 29 and the exhaust port 30 , respectively, with respect to the combustion chamber 21 a .

[0025] The intake port 29 is connected to the intake passage 3 to introduce air supplied from the intake passage 3 into the combustion chamber 21a. The exhaust port 30 is connected to the exhaust passage 4 to discharge exhaust gas generated in the combustion chamber 21a into the exhaust passage 4. The intake valve 31 is opened to allow a mixture of fuel gas and air to be drawn into the combustion chamber 21a via the intake port 29. On the other hand, the exhaust valve 32 is opened to allow exhaust gas generated in the combustion chamber 21a to be discharged via the exhaust port 30.

[0026] The intake passage 3 is connected to the plurality of cylinders 21 of the engine 2 and supplies compressed and cooled air to each cylinder 21. A mixed gas 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 cylinder 21. For example, the intake passage 3 is connected to the engine 2 via an intake manifold 33. The intake manifold 33 has branch flow paths 33a that branch toward the plurality of cylinders 21, and each branch flow path 33a is connected to a respective intake port 29.

[0027] Furthermore, 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 flow passage 33a, the intake port 29, or the cylinder head 25. The amount of ammonia supplied (supply pressure), the supply timing, etc. of the fuel supply unit 36 ​​are controlled by the control device 19. The fuel supply unit 36 ​​may be formed by a venturi mixer that mixes ammonia with air flowing through the intake passage 3, or may be formed by an intake valve, an injector, or the like that is provided corresponding to each combustion chamber 21a and that injects ammonia.

[0028] The exhaust passage 4 is connected to the plurality of cylinders 21 of the engine 2, allowing exhaust gas generated in each cylinder 21 to flow through and be discharged. For example, the exhaust passage 4 is connected to the engine 2 via an exhaust manifold 34. The exhaust manifold 34 has branch flow paths 34a that branch toward the plurality of cylinders 21, and each branch flow path 34a is connected to each exhaust port 30.

[0029] The exhaust passage 4 is connected to a selective reduction catalyst 6 and an ammonia adsorption catalyst 7 on the downstream side in the exhaust direction for treating the 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.

[0030] The selective reduction catalyst 6 is disposed in the exhaust passage 4 and selectively reduces nitrogen oxides contained in the exhaust gas flowing through the exhaust passage 4 using a reducing agent such as urea water, thereby purifying the exhaust gas of ammonia and nitrogen oxides. A reducing agent supply unit 6a is disposed in the exhaust passage 4 upstream of the selective reduction catalyst 6 in the exhaust direction, and supplies reducing agent to the selective reduction catalyst 6. The amount of reducing agent supplied by the reducing agent supply unit 6a is controlled by a control device 19.

[0031] For example, the selective reduction catalyst 6 reduces ammonia and nitrogen oxides by reacting them in a one-to-one concentration or molar ratio (proportion), and the reducing agent supply unit 6a is controlled by the control device 19 to supply the reducing agent in such a manner that the concentration or molar ratio of ammonia and nitrogen oxides introduced into the selective reduction catalyst 6 together with the exhaust gas becomes one to one.

[0032] The ammonia adsorption catalyst 7 is disposed in the exhaust passage 4 upstream of the selective reduction catalyst 6 in the exhaust direction, and adsorbs ammonia contained in the exhaust gas flowing through the exhaust passage 4 to purify the exhaust gas of ammonia. Specifically, the ammonia adsorption catalyst 7 adsorbs ammonia to reduce the concentration and / or molar number of ammonia introduced into the selective reduction catalyst 6 by the exhaust gas.

[0033] For example, the ammonia adsorption catalyst 7 may be composed of activated carbon, zeolite, Prussian blue, MOF (porous metal complex) or PCP (porous coordination polymer) as a material for adsorbing ammonia. Alternatively, the ammonia adsorption catalyst 7 may be composed of Fe ion-exchange zeolite, Cu ion-exchange zeolite, etc. as a material that reacts with nitrogen oxides in addition to the function of adsorbing ammonia.

[0034] Furthermore, when ammonia is adsorbed by the ammonia adsorption catalyst 7, when exhaust gas passes through the ammonia adsorption catalyst 7, the ammonia is desorbed from the ammonia adsorption catalyst 7 by the wind force of the exhaust gas and a reaction with nitrogen oxides. In this case, the ammonia adsorption catalyst 7 can be configured to be capable of desorbing ammonia at a temperature equal to or higher than a predetermined desorption temperature.

[0035] The first bypass passage 8 is connected to the exhaust passage 4 so as to bypass the ammonia adsorption catalyst 7. Specifically, the first bypass passage 8 is connected to the exhaust passage 4 upstream of the ammonia adsorption catalyst 7, downstream of the ammonia adsorption catalyst 7, and upstream of the selective reduction catalyst 6 in the exhaust direction. Furthermore, the exhaust passage 4 may include a check valve or the like to prevent reverse flow from the first bypass passage 8 to the exhaust passage 4, upstream of the junction of the exhaust passage 4 and the outlet of the first bypass passage 8 in the exhaust direction. Furthermore, the first bypass passage 8 may include a check valve or the like to prevent reverse flow from the exhaust passage 4 to the first bypass passage 8, upstream of the junction of the exhaust passage 4 and the outlet of the first bypass passage 8.

[0036] The first path switching valve 9 is disposed in the exhaust passage 4 upstream of the ammonia adsorption catalyst 7 in the exhaust direction, and switches whether exhaust gas flows through the ammonia adsorption catalyst 7. In other words, the path through which exhaust gas from the engine 2 flows solely through the exhaust passage 4 and is discharged via the ammonia adsorption catalyst 7 and the selective reduction catalyst 6 is defined as the main exhaust path 101. The first path switching valve 9 switches whether exhaust gas is permitted to flow through the main exhaust path 101. The first path switching valve 9 is controlled by the control device 19 to switch between an open state and a closed state. In the open state, exhaust gas is permitted to flow through the main exhaust path 101. In the closed state, exhaust gas is prohibited from flowing through the main exhaust path 101.

[0037] The second bypass passage 10 is connected to the exhaust passage 4 in a manner that bypasses the ammonia adsorption catalyst 7 and the selective reduction catalyst 6. Specifically, the second bypass passage 10 is connected to the exhaust passage 4 upstream of the ammonia adsorption catalyst 7 and downstream of the selective reduction catalyst 6 in the exhaust direction. Furthermore, the exhaust passage 4 may include a check valve or the like to prevent reverse flow from the second bypass passage 10 to the exhaust passage 4, located upstream of the confluence of the exhaust passage 4 and the outlet of the second bypass passage 10 in the exhaust direction. Furthermore, the second bypass passage 10 may include a check valve or the like to prevent reverse flow from the exhaust passage 4 to the second bypass passage 10, located upstream of the confluence of the outlet of the exhaust passage 4 and the second bypass passage 10 in the exhaust direction.

[0038] The second path switching valve 11 is disposed in the first bypass passage 8 upstream of the selective reduction catalyst 6 in the exhaust direction, and switches whether exhaust gas flows through the selective reduction catalyst 6. In other words, a path that allows exhaust gas from the engine 2 to flow through the exhaust passage 4 and the first bypass passage 8 without passing through the ammonia adsorption catalyst 7 and then be discharged through the selective reduction catalyst 6 is defined as the first bypass passage 102. The second path switching valve 11 switches whether exhaust gas is permitted to flow through the first bypass passage 102. The second path switching valve 11 is controlled by the control device 19 to switch between an open state and a closed state. In the open state, exhaust gas is permitted to flow through the first bypass passage 102, while in the closed state, exhaust gas is not permitted to flow through the first bypass passage 102.

[0039] The third path switching valve 12 is provided in the second bypass passage 10 and switches whether the exhaust gas bypasses the ammonia adsorption catalyst 7 and the selective reduction catalyst 6 to flow through the exhaust passage 4 and the second bypass passage 10. In other words, the path through which the exhaust gas from the engine 2 flows and is discharged without passing through the ammonia adsorption catalyst 7 and the selective reduction catalyst 6 is defined as the second bypass passage 103. The third path switching valve 12 switches whether the 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 to switch between an open state and a closed state. In the open state, the exhaust gas is permitted to flow through the second bypass passage 103. In the closed state, the exhaust gas is not permitted to flow through the second bypass passage 103.

[0040] exist Figure 1 In the example shown, when the first path switching valve 9 is open and the second path switching valve 11 and the third path switching valve 12 are closed, exhaust gas flows through the main exhaust path 101 and is discharged. Furthermore, when the second path switching valve 11 is open and the first path switching valve 9 and the third path switching valve 12 are closed, exhaust gas flows through the first bypass path 102 and is discharged. Furthermore, when the third path switching valve 12 is open and the first path switching valve 9 and the second path switching valve 11 are closed, exhaust gas flows through the second bypass path 103 and is discharged.

[0041] The first ammonia detection unit 14 is provided in the exhaust passage 4 at a position 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 can calculate the number of moles of ammonia contained in the exhaust gas based on the detection results.

[0042] The first nitrogen oxide detector 15 is provided in the exhaust passage 4 at a position 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 detector 15 detects the emission amount and concentration of nitrogen oxides contained in the exhaust gas and can calculate the number of moles of nitrogen oxides contained in the exhaust gas based on the detection results.

[0043] In addition, Figure 1 , an example is shown in which the first nitrogen oxide detector 15 is disposed upstream of the first ammonia detector 14 in the exhaust passage 4 in the exhaust direction. However, the present invention is not limited to this example. Alternatively, the first ammonia detector 14 may be disposed upstream of the first nitrogen oxide detector 15 in the exhaust direction. In this embodiment, an example is described in which the first ammonia detector 14 and the first nitrogen oxide detector 15 are formed as separate devices or sensors. However, the present invention is not limited to this example. Alternatively, the first ammonia detector 14 and the first nitrogen oxide detector 15 may be formed as an integrated device or sensor.

[0044] The second ammonia detection unit 16 is provided in the exhaust passage 4 at a position downstream of the ammonia adsorption catalyst 7 in the exhaust direction and upstream of the selective reduction catalyst 6, specifically, upstream of the confluence of the exhaust passage 4 and the outlet of the first bypass passage 8 in the exhaust direction, 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 can calculate the number of moles of ammonia contained in the exhaust gas based on the detection results.

[0045] The second nitrogen oxide detector 17 is provided in the exhaust passage 4 at a position downstream of the ammonia adsorption catalyst 7 in the exhaust direction and upstream of the selective reduction catalyst 6, specifically, upstream of the confluence of the exhaust passage 4 and the outlet of the first bypass passage 8 in the exhaust direction, and detects nitrogen oxides contained in the exhaust gas flowing through the exhaust passage 4. For example, the second nitrogen oxide detector 17 detects the emission amount and concentration of nitrogen oxides contained in the exhaust gas and can also calculate the number of moles of nitrogen oxides contained in the exhaust gas based on the detection results.

[0046] In addition, Figure 1, an example is shown in which the second nitrogen oxide detector 17 is arranged upstream of the second ammonia detector 16 in the exhaust passage 4 in the exhaust direction, but the present invention is not limited to this example. Alternatively, the second ammonia detector 16 may be arranged upstream of the second nitrogen oxide detector 17 in the exhaust direction. In this embodiment, an example is described in which the second ammonia detector 6 and the second nitrogen oxide detector 17 are composed of separate devices or sensors. However, the present invention is not limited to this example. Alternatively, the second ammonia detector 16 and the second nitrogen oxide detector 17 may be composed of an integrated device or sensor.

[0047] The temperature detection unit 18 detects the temperature of the exhaust gas exhausted 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 at a position upstream of the ammonia adsorption catalyst 7 in the exhaust direction, specifically, at a position downstream of the branch point between the exhaust passage 4 and the inlet of the first bypass passage 8 in the exhaust direction, and detects the temperature of the exhaust gas introduced from the exhaust passage 4 into 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.

[0048] The control device 19 is a computer such as an ECU (Engine Control Unit) that controls the operation of the engine 2. It includes a CPU, ROM, RAM, etc., and is configured to control various components of the engine 2. The control device 19 can store various programs for controlling the engine 2 and control the engine 2 by reading and executing the programs.

[0049] For example, the control device 19 controls the reducing agent supply unit 6a based on the detection results of the second ammonia detection unit 16 and the second nitrogen oxide detection unit 17 so that the ratio of the concentration or molar number of ammonia and nitrogen oxides introduced into the selective reduction catalyst 6 together with the exhaust gas reaches a specified ratio (for example, one to one), and controls the supply amount of the reducing agent supplied to the selective reduction catalyst 6.

[0050] Furthermore, the control device 19 determines whether to cause the exhaust gas to flow through the ammonia adsorption catalyst 7 and the selective reduction catalyst 6 based on the ratio of the concentration or molar number of unburned ammonia and the ratio of the concentration or molar number of nitrogen oxides in the exhaust gas exhausted from the engine 2. Preferably, the control device 19 determines whether to cause the exhaust gas to flow through the ammonia adsorption catalyst 7 and the selective reduction catalyst 6 based on the amount of ammonia adsorbed by the ammonia adsorption catalyst 7 in addition to the ratio of unburned ammonia and the ratio of nitrogen oxides. Based on the result of this determination, the control device 19 controls the operation of the first path switching valve 9. Preferably, the control device 19 controls the flow of the exhaust gas by controlling 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.

[0051] Here, the control device 19 obtains the ratio of unburned ammonia and the ratio of nitrogen oxides in the exhaust gas located upstream of the ammonia adsorption catalyst 7 in the exhaust passage 4, specifically, located 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 obtains the ratio of ammonia and the ratio of nitrogen oxides based on the detection results of the first ammonia detection unit 14 and the detection results of the first nitrogen oxide detection unit 15.

[0052] Furthermore, the control device 19 calculates or estimates the amount of ammonia adsorbed by 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 results of the first ammonia detection unit 14 and the detection results of the first nitrogen oxide detection unit 15. The control device 19 obtains the amount of ammonia adsorption using a model that calculates the amount of ammonia adsorbed by 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.

[0053] Furthermore, the control device 19 controls the path through which the exhaust gas flows, switching the path to one of the main discharge path 101, the first bypass path 102, and the second bypass path 103, based on the ammonia ratio and the nitrogen oxide ratio detected by the first ammonia detector 14 and the first nitrogen oxide detector 15. Preferably, the control device 19 controls the operation of the first path switching valve 9 based on the amount of ammonia adsorbed by the ammonia adsorption catalyst 7 in addition to the ammonia ratio and the nitrogen oxide ratio. Preferably, the control device 19 switches the path through which the exhaust gas flows by controlling the operations of the second path switching valve 11 and the third path switching valve 12 in addition to the first path switching valve 9.

[0054] 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 ammonia adsorption amount of the ammonia adsorption catalyst 7 is greater than the prescribed 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 exhaust path 101, thereby discharging the exhaust gas through the ammonia adsorption catalyst 7 and the selective reduction catalyst 6.

[0055] In addition, 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 less than the prescribed 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 discharging the exhaust gas through the selective reduction catalyst 6 instead of the ammonia adsorption catalyst 7.

[0056] Furthermore, regardless of the ratio of nitrogen oxides and 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.

[0057] For example, the control device 19 may determine that an abnormality has occurred in the operating state of the engine 2 when parameters set for supplying ammonia to the engine 2 (e.g., load, fuel injection pressure, fuel injection timing, excess air ratio, etc.) are outside a safe range. The control device 19 may determine that an abnormality has occurred in the operating state of the engine 2 when a sensor for detecting ammonia and nitrogen oxides located downstream of the selective reduction catalyst 6 in the exhaust direction detects a predetermined amount or more of ammonia and nitrogen oxides.

[0058] As described above, according to the present embodiment, an engine device 1 includes an engine 2 that operates using a fuel containing at least ammonia, and includes: an exhaust passage 4 through which exhaust gas discharged from the engine 2 flows in the exhaust direction; a selective reduction catalyst 6 that reduces nitrogen oxides contained in the exhaust gas using a reducing agent in the exhaust passage 4; an ammonia adsorption catalyst 7 that adsorbs ammonia contained in the exhaust gas in the exhaust passage 4, located upstream of the selective reduction catalyst 6 in the exhaust direction; a first bypass passage 8 that is 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 exhaust gas flows through the ammonia adsorption catalyst 7. For example, the first path switching valve 9 is located upstream of the ammonia adsorption catalyst 7 in the exhaust direction.

[0059] As a result, the engine device 1 can achieve a compact device while maintaining good exhaust gas properties and purifying the exhaust gas while reducing the amount of reducing agent used. For example, the engine device 1 can adsorb excess ammonia in the exhaust gas using the ammonia adsorption catalyst 7, allowing the exhaust gas with reduced ammonia to flow downstream. The selective reduction catalyst 6 on the downstream side can then introduce and purify the exhaust gas with an appropriate ammonia / nitrogen oxide ratio.

[0060] Furthermore, the engine device 1 does not oxidize and remove the ammonia adsorbed by the ammonia adsorption catalyst 7, but instead uses the exhaust gas to splash the ammonia and circulate it downstream, thereby forming a nitrogen oxide purification source. This reduces the amount of reducing agent required to supply the selective reduction catalyst 6, thus saving reducing agent and improving the purification efficiency of ammonia and nitrogen oxides. Therefore, it is no longer necessary for the ammonia adsorption catalyst 7 to treat all ammonia in the exhaust gas, allowing the ammonia adsorption catalyst 7 to be miniaturized.

[0061] Furthermore, the engine device 1 can utilize the first bypass passage 8 to bypass the ammonia adsorption catalyst 7 and discharge the exhaust gas, thereby controlling the use of the ammonia adsorption catalyst 7 and achieving a longer life. The selective reduction catalyst 6 on the downstream side can be utilized to supply a reducing agent in such a manner that the ratio of ammonia to nitrogen oxides introduced with the exhaust gas becomes appropriate, thereby purifying ammonia and nitrogen oxides.

[0062] In this manner, in order to purify ammonia and nitrogen oxides in the exhaust gas at an appropriate ratio using the selective reduction catalyst 6, the engine device 1 can not only control the combustion of the engine 2 and the supply of the reducing agent, but also, depending on the situation, utilize the ammonia adsorption catalyst 7 to adjust the ratio of ammonia and nitrogen oxides introduced into the selective reduction catalyst 6 to an appropriate level. Therefore, the engine device 1 does not need to control the ratio of ammonia and nitrogen oxides in the exhaust gas discharged from the engine 2 to a constant range solely through the combustion of the engine 2, and can operate the engine 2 with an emphasis on fuel efficiency.

[0063] Furthermore, 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 the exhaust gas is allowed to flow 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.

[0064] Thus, the engine device 1 uses the second bypass passage 10 to discharge exhaust gas by bypassing the ammonia adsorption catalyst 7 and the selective reduction catalyst 6. This allows the use of the ammonia adsorption catalyst 7 and the selective reduction catalyst 6 to be controlled, thereby extending the service life of the ammonia adsorption catalyst 7 and the selective reduction catalyst 6. Furthermore, if an abnormality occurs in the engine 2 (exhaust gas abnormality) or in the ammonia adsorption catalyst 7 or the selective reduction catalyst 6, damage to the ammonia adsorption catalyst 7 and the selective reduction catalyst 6 due to the introduction of exhaust gas can be suppressed.

[0065] In addition, according to the present embodiment, the engine device 1 is further provided in the exhaust passage 4 at a position upstream of the ammonia adsorption catalyst 7 in the exhaust direction: a first ammonia detection unit 14 for detecting ammonia contained in the exhaust gas; and a first nitrogen oxide detection unit 15 for detecting nitrogen oxides contained in the exhaust gas, and the operation of the first path switching valve 9 is controlled based on the detection results of the first ammonia detection unit 14 and the first nitrogen oxide detection unit 15.

[0066] Thus, the engine device 1 can selectively switch the path through which the exhaust gas flows with a simple configuration using the first ammonia detector 14 , the first nitrogen oxide detector 15 , and the first path switching valve 9 .

[0067] In addition, according to the present embodiment, the engine device 1 is further provided in the exhaust passage 4 at a position downstream of the ammonia adsorption catalyst 7 and upstream of the selective reduction catalyst 6 in the exhaust direction: a second ammonia detection unit 16 for detecting ammonia contained in the exhaust gas; and a second nitrogen oxide detection unit 17 for detecting nitrogen oxides contained in the exhaust gas.

[0068] Thus, the engine device 1 can determine the amount of reducing agent supplied to the selective reduction catalyst 6 with a simple configuration using the second ammonia detection unit 16 and the second nitrogen oxide detection unit 17 .

[0069] In addition, 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. The control device 19 calculates or estimates the amount of ammonia adsorbed by 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 ammonia adsorption amount.

[0070] Thus, the engine device 1 can appropriately determine the path through which the exhaust gas flows, taking into account the amount of ammonia adsorbed by the ammonia adsorption catalyst 7 , and selectively switch the path.

[0071] 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 amount of ammonia adsorbed by the ammonia adsorption catalyst 7 is greater than a predetermined adsorption amount threshold, the engine device 1 discharges the exhaust gas via 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 amount of ammonia adsorbed by the ammonia adsorption catalyst 7 is less than a predetermined adsorption amount threshold, the engine device 1 discharges the exhaust gas via the selective reduction catalyst 6, not via the ammonia adsorption catalyst 7. Furthermore, regardless of the ratio of nitrogen oxides and the ratio of ammonia in the exhaust gas, if an abnormality occurs in the operating state of the engine 2 or the selective reduction catalyst 6, the engine device 1 discharges the exhaust gas via the ammonia adsorption catalyst 7 and the selective reduction catalyst 6, not via the ammonia adsorption catalyst 7 and the selective reduction catalyst 6.

[0072] Thus, the engine device 1 can more appropriately determine the path through which the exhaust gas flows and selectively switch the path, taking into account the ratio of ammonia and the ratio of nitrogen oxides in the exhaust gas and the amount of ammonia adsorbed by the ammonia adsorption catalyst 7 .

[0073] In addition, Figure 1 , an example is shown in which the first path switching valve 9 is arranged in the exhaust passage 4 at a position further downstream in the exhaust direction than the branch point at the inlet of the exhaust passage 4 and the first bypass passage 8, but the present invention is not limited to this example, or the first path switching valve 9 can be arranged at the branch point at the inlet of the exhaust passage 4 and the first bypass passage 8.

[0074] In addition, Figure 1 , an example is shown in which the second bypass passage 10 is connected to the first bypass passage 8 at a position further downstream in the exhaust direction than 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 at a position further upstream in the exhaust direction than the branch point between the exhaust passage 4 and the inlet of the first bypass passage 8.

[0075] In addition, Figure 1 , an example is shown in which the second path switching valve 11 is provided in the first bypass passage 8 at a position downstream in the exhaust direction relative to the branching point between the inlets of the first bypass passage 8 and the second bypass passage 10. However, the present invention is not limited to this example. Alternatively, the second path switching valve 11 may be provided at the branching 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 either the first bypass passage 8 or the second bypass passage 10, or to selectively allow exhaust gas to flow into either the first bypass passage 8 or the second bypass passage 10. In this configuration, the third path switching valve 12 may be omitted.

[0076] In addition, in the above embodiment, the following example is described: in order to determine whether to allow the exhaust gas to flow through the ammonia adsorption catalyst 7 and the selective reduction catalyst 6, the control device 19 obtains the ratio (for example, concentration or molar number) of ammonia and nitrogen oxides discharged from the engine 2 based on the detection results of the first ammonia detection unit 14 and the detection results of the first nitrogen oxide detection unit 15, but the present invention is not limited to this example.

[0077] In another example, the engine device 1 detects or measures the ratio (proportion) and emission amount of ammonia and nitrogen oxides emitted when the engine 2 is operated under various operating conditions (engine speed, load, etc.). The control device 19 pre-stores data as exhaust gas information that associates each operating condition with the ratio and / or emission amount of ammonia and nitrogen oxides corresponding to each operating condition. Furthermore, the engine device 1 can obtain exhaust gas information by experimentally operating the engine 2 and / or can obtain and store exhaust gas information when the engine 2 is actually operated. Furthermore, the control device 19 obtains the operating conditions under which the engine 2 is operated and, based on these operating conditions and the pre-stored exhaust gas information, obtains the ratio data (proportion data) and / or emission amount data of ammonia and nitrogen oxides corresponding to these operating conditions.

[0078] In this case, the control device 19 controls the operation of the first path switching valve 9 based on the acquired ammonia and nitrogen oxide ratio data and / or emission data, in the same manner as in the above-mentioned embodiment. Preferably, on the basis of the first path switching valve 9, the operation of the second path switching valve 11 and the third path switching valve 12 is also controlled to control the flow of exhaust gas.

[0079] Thus, 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. This eliminates the need for the first ammonia detector 14 and the first nitrogen oxide detector 15 and simplifies the structure.

[0080] In addition, in the above-mentioned embodiment, the following example is described: in order to determine whether to allow the exhaust gas to flow through the ammonia adsorption catalyst 7 and the selective reduction catalyst 6, the control device 19 calculates the ammonia adsorption amount of the ammonia adsorption catalyst 7 based on the temperature of the exhaust gas or the temperature of the ammonia adsorption catalyst 7 detected by the temperature detection unit 18, the ammonia concentration detected by the first ammonia detection unit 14, and the nitrogen oxide concentration detected by the first nitrogen oxide detection unit 15, but the present invention is not limited to this example.

[0081] In another example, the control device 19 acquires ammonia and nitrogen oxide ratio data (proportional data) and / or emission data corresponding to the operating conditions when the engine 2 is operating based on pre-stored exhaust gas information, and calculates the ammonia concentration and the nitrogen oxide concentration based on the acquired ammonia and nitrogen oxide ratio data and / or emission data. Furthermore, the control device 19 calculates the ammonia adsorption amount of the ammonia adsorption catalyst 7 based on the exhaust gas temperature 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.

[0082] In this case, the control device 19 controls the operation of the first path switching valve 9 based on the ammonia ratio and nitrogen oxide ratio calculated based on the exhaust gas information, and also based on the ammonia adsorption amount of the ammonia adsorption catalyst 7 calculated based on the exhaust gas information, in the same manner as in the above-mentioned embodiment. Preferably, on the basis of the first path switching valve 9, the operation of the second path switching valve 11 and the third path switching valve 12 is also controlled to control the flow of exhaust gas.

[0083] Thus, the engine device 1 can not only simplify the structure by omitting the first ammonia detection unit 14 and the first nitrogen oxide detection unit 15 using the exhaust gas information, but can also calculate the ammonia adsorption amount of the ammonia adsorption catalyst 7 and appropriately determine the path for the exhaust gas to flow based on the ammonia adsorption amount and selectively switch it.

[0084] In addition, in the above-mentioned embodiment, the following example is described: when the ratio of nitrogen oxides in the exhaust gas is higher than the ratio of ammonia, when the ammonia adsorption amount of the ammonia adsorption catalyst 7 is greater than the prescribed adsorption amount threshold, the control device 19 switches to the main exhaust path 101. On the other hand, when the ammonia adsorption amount of the ammonia adsorption catalyst 7 is less than the prescribed adsorption amount threshold, it switches to the first bypass path 102, but the present invention is not limited to this example.

[0085] 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 amount of ammonia adsorbed by the ammonia adsorption catalyst 7 using multiple threshold levels and switch the exhaust gas flow path in stages. For example, the control device 19 may predetermine a first adsorption amount threshold and a second adsorption amount threshold that is less than the first adsorption amount threshold. When the ammonia adsorption amount exceeds the first adsorption amount threshold, the control device 19 switches the exhaust gas flow path to the main discharge path 101. When the ammonia adsorption amount is below the first adsorption amount threshold and above the second adsorption amount threshold, the control device 19 switches the exhaust gas flow path to both the main discharge path 101 and the first bypass path 102. When the ammonia adsorption amount is below the second adsorption amount threshold, the control device 19 switches the exhaust gas flow path to the first bypass path 102. Furthermore, when utilizing both the main discharge path 101 and the first bypass path 102, the control device 19 uses the first path switching valve 9 and the second path switching valve 11 to adjust the flow rates in the main discharge path 101 and the first bypass path 102 to avoid pressure loss.

[0086] Furthermore, the present invention may be modified as appropriate within the scope not departing from the gist or concept of the invention as reflected in the claims and the entire specification, and engine devices with such modifications are also encompassed within the technical concept of the present invention.

[0087] [Supplementary Notes on the Invention]

[0088] The following is a supplementary note on the outline of the invention extracted from the above embodiments. In addition, the various structures and processing functions described in the following supplementary notes can be selected and combined arbitrarily.

[0089] Note 1

[0090] An engine device including an engine operated by a fuel containing at least ammonia, characterized in that:

[0091] The engine device comprises:

[0092] an exhaust passage for allowing exhaust gas discharged from the engine to flow in an exhaust direction;

[0093] selecting a reducing catalyst that reduces nitrogen oxides contained in the exhaust gas using a reducing agent in the exhaust passage;

[0094] an ammonia adsorption catalyst that adsorbs ammonia contained in the exhaust gas in the exhaust passage and is located upstream of the selective reduction catalyst in the exhaust direction;

[0095] a first bypass passage connected to the exhaust passage so as to bypass the ammonia adsorption catalyst; and

[0096] The first path switching valve switches whether the exhaust gas is allowed to flow through the ammonia adsorption catalyst.

[0097] Note 2

[0098] The engine device according to Supplementary Note 1 is characterized in that:

[0099] The first path switching valve is provided upstream of the ammonia adsorption catalyst in the exhaust direction.

[0100] Note 3

[0101] The engine device according to Supplementary Note 1 is characterized in that:

[0102] The engine device further comprises:

[0103] a second bypass passage connected to the exhaust passage in a manner bypassing the ammonia adsorption catalyst and the selective reduction catalyst; and

[0104] The second path switching valve switches whether the exhaust gas is allowed to flow through the selective reduction catalyst.

[0105] Note 4

[0106] The engine device according to Supplementary Note 3 is characterized in that:

[0107] The second path switching valve is provided upstream of the selective reduction catalyst in the exhaust direction.

[0108] Note 5

[0109] The engine device according to any one of Supplementary Notes 1 to 4, characterized in that:

[0110] The engine device further includes: a first ammonia detector provided in the exhaust passage upstream of the ammonia adsorption catalyst in the exhaust direction and configured to detect ammonia contained in the exhaust gas; and a first nitrogen oxide detector configured to detect nitrogen oxides contained in the exhaust gas.

[0111] The operation of the first path switching valve is controlled based on the detection results of the first ammonia detector and the first nitrogen oxide detector.

[0112] <Note 6>

[0113] The engine device according to Supplementary Note 5 is characterized in that:

[0114] The exhaust passage is further provided with: a second ammonia detector for detecting ammonia contained in the exhaust gas; and a second nitrogen oxide detector for detecting nitrogen oxides contained in the exhaust gas, located downstream of the ammonia adsorption catalyst and upstream of the selective reduction catalyst in the exhaust direction.

[0115] <Note 7>

[0116] The engine device according to any one of Supplementary Notes 1 to 6, characterized in that:

[0117] The engine device further includes a control device for controlling the operation of the first path switching valve.

[0118] The control device controls the operation of the first path switching valve based on ratio data of ammonia and nitrogen oxides contained in the exhaust gas under the operating conditions of the engine and / or emission amount data.

[0119] <Note 8>

[0120] The engine device according to Supplement 5 or 6 is characterized in that

[0121] The engine device further comprises:

[0122] a control device for controlling the operation of the first path switching valve; and

[0123] a temperature detection unit that detects the temperature of the exhaust gas or the temperature of the ammonia adsorption catalyst,

[0124] The control device calculates or estimates an amount of ammonia adsorbed by the ammonia adsorption catalyst based on detection results of the first ammonia detector, the first nitrogen oxide detector, and the temperature detector, and controls operation of the first path switching valve based on the amount of ammonia adsorbed.

[0125] <Note 9>

[0126] The engine device according to Supplementary Note 7 is characterized in that:

[0127] The engine device further includes a temperature detection unit that detects the temperature of the exhaust gas or the temperature of the ammonia adsorption catalyst.

[0128] The control device calculates or estimates an amount of ammonia adsorbed by the ammonia adsorption catalyst based on the ratio data and / or the discharge amount data and a detection result of the temperature detection unit, and controls operation of the first path switching valve based on the amount of ammonia adsorbed.

[0129] <Note 10>

[0130] The engine device according to any one of Supplementary Notes 1 to 9, characterized in that:

[0131] 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 is greater than a predetermined adsorption amount threshold, the exhaust gas is discharged through the ammonia adsorption catalyst and the selective reduction catalyst.

[0132] 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 is less than a predetermined adsorption amount threshold, the exhaust gas is discharged through the selective reduction catalyst instead of the ammonia adsorption catalyst.

[0133] <Note 11>

[0134] The engine device according to any one of Supplementary Notes 1 to 10, characterized in that:

[0135] Regardless of the ratio of nitrogen oxides and the ratio of ammonia in the exhaust gas, if 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.

Claims

1. An engine device comprising an engine operated by a fuel containing at least ammonia, It is characterized by: The engine device comprises: an exhaust passage for allowing exhaust gas discharged from the engine to flow in an exhaust direction; selecting a reducing catalyst that reduces nitrogen oxides contained in the exhaust gas using a reducing agent in the exhaust passage; an ammonia adsorption catalyst that adsorbs ammonia contained in the exhaust gas in the exhaust passage and is located upstream of the selective reduction catalyst in the exhaust direction; a first bypass passage connected to the exhaust passage in a manner bypassing the ammonia adsorption catalyst; as well as The first path switching valve switches whether the exhaust gas is allowed to flow through the ammonia adsorption catalyst.

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

3. The engine device according to claim 1, characterized in that The engine device further comprises: a second bypass passage connected to the exhaust passage in a manner bypassing the ammonia adsorption catalyst and the selective reduction catalyst; and The second path switching valve switches whether the exhaust gas is allowed to flow through the selective reduction catalyst.

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

5. The engine device according to claim 1, characterized in that The engine device further includes: a first ammonia detector that detects ammonia contained in the exhaust gas in the exhaust passage at a position upstream of the ammonia adsorption catalyst in the exhaust direction; and a first nitrogen oxide detector that detects nitrogen oxides contained in the exhaust gas. The operation of the first path switching valve is controlled based on the detection results of the first ammonia detector and the first nitrogen oxide detector.

6. The engine device according to claim 5, characterized in that The exhaust passage is further provided with: a second ammonia detector for detecting ammonia contained in the exhaust gas; and a second nitrogen oxide detector for detecting nitrogen oxides contained in the exhaust gas, located downstream of the ammonia adsorption catalyst and upstream of the selective reduction catalyst in the exhaust direction.

7. The engine device according to claim 1, characterized in that The engine device further includes a control device for controlling the operation of the first path switching valve. The control device controls the operation of the first path switching valve based on ratio data of ammonia and nitrogen oxides contained in the exhaust gas under the operating conditions of the engine and / or emission amount data.

8. The engine device according to claim 5, characterized in that The engine device further comprises: a control device for controlling the operation of the first path switching valve; and a temperature detection unit that detects the temperature of the exhaust gas or the temperature of the ammonia adsorption catalyst, The control device calculates or estimates an amount of ammonia adsorbed by the ammonia adsorption catalyst based on detection results of the first ammonia detector, the first nitrogen oxide detector, and the temperature detector, and controls operation of the first path switching valve based on the amount of ammonia adsorbed.

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

10. The engine device according to claim 1, characterized in that 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 is greater than a predetermined adsorption amount threshold, the exhaust gas is discharged through the ammonia adsorption catalyst and the selective reduction catalyst. 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 is less than a predetermined adsorption amount threshold, the exhaust gas is discharged through the selective reduction catalyst instead of the ammonia adsorption catalyst.

11. The engine device according to claim 1, characterized in that Regardless of the ratio of nitrogen oxides and the ratio of ammonia in the exhaust gas, if 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.

Images