Engine and outboard motor

Abstract

To provide a technology for improving exhaust emission control performance in an engine.SOLUTION: The engine E includes an engine body 1 in which a cylinder bore center line is oriented in a horizontal direction, an exhaust pipe 32, and an exhaust purification device 33. The exhaust emission control device 33 includes an exhaust emission control catalyst 332 in which a catalyst component is carried on a catalyst carrier, first and second exhaust filters 332, 333 disposed so as to sandwich the exhaust emission control catalyst 332 from front and rear sides with respect to an exhaust flow direction, and a casing 334 that houses these exhaust emission control elements 331, 333, 331 and is attachable to and detachable from the exhaust pipe 32. After being detached from the exhaust pipe 32, the housing 334 can be attached by reversing the front-rear direction.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to an engine and an outboard motor. [Background technology]

[0002] In an outboard motor, the crankshaft is mounted upright and the cylinders are horizontally oriented. In such a horizontally oriented engine, the centerline of the cylinder bore of the engine body faces horizontally. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Special Publication No. 62-028288 Summary of the Invention [Problem to be solved by the invention]

[0004] During combustion in an engine, catalyst poisoning substances such as phosphorus, sulfur, and calcium are generated from engine oil. These catalyst poisoning substances inhibit the catalytic purification reaction of harmful exhaust components in the exhaust, resulting in a decrease in the performance of the exhaust purification device.

[0005] In a horizontally positioned engine, engine oil tends to accumulate on the inner circumference of the cylinder liner, increasing the amount of engine oil that leaks past the piston ring seal into the combustion chamber. This results in a large amount of catalyst poisoning substances being generated, which significantly reduces exhaust purification performance.

[0006] There is a demand for further improvements in exhaust purification performance, not only for engines installed in outboard motors, but for engines in general.

[0007] In view of the above circumstances, an object of the present invention is to provide a technique that contributes to improving the exhaust purification performance of a horizontally-oriented engine. [Means for solving the problem]

[0008] In order to solve the above-mentioned problems, an engine according to one aspect of the present invention comprises an engine body in which the center lines of the cylinder bores are oriented horizontally and the pistons are free to reciprocate horizontally within the bores of the cylinders along the center lines of the cylinder bores, an exhaust pipe connected to the engine body so as to allow exhaust gas to flow therethrough, and an exhaust purification device interposed in the exhaust pipe, the exhaust purification device comprising an exhaust purification catalyst having a catalyst carrier and having a catalyst component that promotes an exhaust purification reaction carried on the catalyst carrier, and catalysts arranged to sandwich the exhaust purification catalyst from the front and rear in the exhaust flow direction, and which are capable of purifying particulate matter in the exhaust The exhaust system comprises first and second exhaust filters capable of capturing exhaust gas, and a housing that houses the exhaust purification catalyst, the first exhaust filter, and the second exhaust filter and is configured to be attachable and detachable to the exhaust pipe. After being removed from the exhaust pipe, the housing can be attached to the exhaust pipe by switching its front-to-back orientation, and is switchable between a first operating state before removal, in which exhaust flows from the first exhaust filter to the second exhaust filter via the exhaust purification catalyst, and a second operating state after attachment, in which exhaust flows from the second exhaust filter to the first exhaust filter via the exhaust purification catalyst.

[0009] An outboard motor according to another aspect of the present invention includes the engine, a propeller shaft arranged in a direction intersecting the crankshaft, a power transmission mechanism configured to transmit torque of the crankshaft to the propeller shaft, and a propeller attached to the shaft end of the propeller shaft. [Effects of the Invention]

[0010] According to one embodiment of the present invention, catalyst poisoning substances derived from engine oil are captured by the upstream exhaust filter, making it possible to suppress the inflow of catalyst poisoning substances into the exhaust purification catalyst and the resulting decline in exhaust purification performance. Furthermore, because the housing is detachable from the exhaust pipe, when the accumulation of ash remaining in the exhaust filter progresses beyond a certain level due to the deposition of particulate matter in the exhaust and repeated regeneration of the exhaust filter, the exhaust purification device together with the housing can be removed from the exhaust pipe and reattached with the front and rear orientation reversed, allowing the ash to be removed from the exhaust filter (i.e., the exhaust filter located downstream after the front and rear swap) by the exhaust pressure, thereby enabling the filter function to be restored. [Brief explanation of the drawings]

[0011] [Figure 1] 1 is a schematic diagram showing the overall configuration of an engine according to an embodiment of the present invention. [Figure 2] FIG. 2 is a cross-sectional view showing an internal configuration of the exhaust gas purification device according to the embodiment of the present invention. [Figure 3] FIG. 2 is an enlarged cross-sectional view schematically showing the configuration of exhaust filters (first exhaust filter, second exhaust filter) according to the embodiment. [Figure 4] 3 is a flowchart showing the flow of exhaust purification control (catalyst regeneration processing) according to the embodiment. [Figure 5] 3 is a flowchart showing the flow of exhaust purification control (monitoring and inspection processing) according to the embodiment. [Figure 6] 10 is a flowchart showing the flow of the first half (notification of front and rear replacement timing) of the monitoring and inspection process according to the embodiment. [Figure 7] 10 is a flowchart showing the flow of the latter half of the monitoring and inspection process (notification of the time for cleaning and replacing the filter) according to the embodiment. [Figure 8] FIG. 10 is a schematic diagram showing the effect (removal of ash) of switching the exhaust gas purification device front and rear. [Figure 9] FIG. 4 is a cross-sectional view that schematically shows the internal configuration of an exhaust gas purification device according to another embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0012] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings.

[0013] (Overall engine configuration) FIG. 1 is a schematic diagram showing the overall configuration of an internal combustion engine (hereinafter simply referred to as "engine") E according to one embodiment of the present invention.

[0014] In the following description, the terms "upstream" and "downstream" are used in relation to the direction of flow of exhaust gas emitted from engine E. For example, the upstream side of the exhaust purification device refers to the upstream side of the exhaust purification device in the direction of exhaust gas flow, and the downstream side of the exhaust purification device refers to the downstream side of the exhaust purification device in the direction of exhaust gas flow.

[0015] In this embodiment, the engine E constitutes a drive source for an outboard motor, and the outboard motor is mounted to the rear of the hull by a transom bracket.

[0016] The engine E includes an engine body 1 having a combustion chamber, an intake system 2, and an exhaust system 3. The engine E according to this embodiment is a four-stroke engine with four cylinders arranged in line, but the type of the engine E, that is, the number and arrangement of the cylinders in the engine E, and further the number of strokes of the engine E, are not limited to this. In addition to four-cylinder four-stroke in-line engines, various engines can be used, such as single-cylinder, six-cylinder, V-type arrangement, and two-stroke engines.

[0017] The engine body 1 includes a cylinder block, a cylinder head, and a crankcase. A piston is inserted into the cylinder block, and the space formed between the piston crown and the inner surface of the cylinder head forms the combustion chamber. When the outboard motor is mounted to the rear of the hull, the engine E is positioned so that the central axis of the cylinder bore of the engine body 1 faces in the fore-and-aft direction of the hull (the direction perpendicular to the plane of the paper in Figure 1, hereinafter referred to as the "fore-and-aft direction") and the piston reciprocates in the fore-and-aft direction.

[0018] The power generated by combustion in the engine E is transmitted to a drive shaft 41 via a crankshaft 11 connected to the pistons and arranged upright, and further to a propeller shaft 42 extending in the front-to-rear direction, rotating a propeller 43 attached to the rear end of the propeller shaft 42. A power transmission mechanism 44 is interposed between the drive shaft 41 and the propeller shaft 42. The power transmission mechanism 44 converts the rotation of the drive shaft 42 into rotation of the propeller shaft 42 and switches the rotation direction of the propeller shaft 42 between a forward direction when moving forward and a reverse direction when moving backward. The power transmission mechanism 44 has a pinion gear attached to the drive shaft 41 and a forward and reverse reduction gear attached to the propeller shaft 42 that selectively meshes with the pinion gear.

[0019] The intake system 2 includes a surge tank 21 and an intake manifold 22, as well as an air cleaner (not shown) attached to an opening 21a of the surge tank 21. Air from which foreign matter such as dust has been removed via the air cleaner is introduced into the surge tank 21. The intake manifold 22 branches off from the surge tank 21 and is connected to the side of the cylinder head. The air that has flowed into the surge tank 21 is distributed to each cylinder via the intake manifold 22.

[0020] A fuel injector 51 is provided in the cylinder head for each cylinder, and the fuel injected by the fuel injector 51 is mixed with air that has passed through the intake manifold 22 and introduced into the corresponding cylinder. Inside the cylinder, the fuel and air continue to mix, forming an air-fuel mixture. This mixture is then ignited by a spark plug 61, causing the mixture to burn.

[0021] The exhaust system 3 includes an exhaust manifold 31, an exhaust pipe 32, and a catalytic converter 33. In this embodiment, the exhaust pipe 32 extends vertically parallel to the cylinder arrangement direction, and the catalytic converter 33 is installed near the outlet or lower end of the exhaust pipe 32 with its centerline (hereinafter referred to as the "front-to-rear centerline") vertically aligned. After combustion, exhaust gas remaining in the cylinders is discharged into the exhaust manifold 31 and flows into the exhaust pipe 32 via a collecting section of the exhaust manifold 31. The exhaust gas then passes downward through the catalytic converter 33, where harmful components in the exhaust gas are purified before being discharged from the exhaust pipe 32. The exhaust gas then passes through a flow path formed around the propeller shaft 42 and is released into seawater. The catalytic converter 33 constitutes an "exhaust gas purification device" according to this embodiment.

[0022] (Catalytic converter configuration) FIG. 2 is a cross-sectional view that schematically shows the internal configuration of the catalytic converter 33. As shown in FIG.

[0023] The catalytic converter 33 includes a first exhaust filter 331, an exhaust purification catalyst 332, and a second exhaust filter 333, and these exhaust purification elements 331, 332, 333 are housed in a housing 334. The two exhaust filters 331, 333 are positioned such that they sandwich the exhaust purification catalyst 332 from the front and rear in the direction in which the exhaust passes through the catalytic converter 33 (i.e., the exhaust flow direction) A. The first exhaust filter 331 and the exhaust purification catalyst 332 are spaced apart from each other in the exhaust flow direction A, and the second exhaust filter 333 and the exhaust purification catalyst 332 are also spaced apart from each other in the exhaust flow direction A. In other words, the first exhaust filter 331, the exhaust purification catalyst 332, and the second exhaust filter 333 are not in close contact with each other, and a space of a fixed length is secured in the exhaust flow direction A between the first exhaust filter 331 and the exhaust purification catalyst 332 and between the exhaust purification catalyst 332 and the second exhaust filter 333, respectively. These spaces contribute to disturbing the flow of exhaust gas and promoting agitation of the exhaust gas.

[0024] The first exhaust filter 331 is a filter medium having a mesh size large enough to capture particulate matter in the exhaust gas. The first exhaust filter 331 can be realized, for example, by a gasoline particulate filter. In this embodiment, in addition to particulate matter, the first exhaust filter 331 also captures catalyst-poisoning substances derived from engine oil, such as phosphorus, sulfur, and calcium.

[0025] The exhaust purification catalyst 332 has a configuration in which a catalyst component that promotes the purification reaction of harmful components in the exhaust (i.e., the exhaust purification reaction) is supported on a carrier, and is a so-called three-way catalyst that uses precious metals such as platinum, palladium, and rhodium as the catalyst component. When the engine E is operated at a stoichiometric air-fuel ratio, the three-way catalyst simultaneously oxidizes the harmful exhaust components, total hydrocarbons (THC) and carbon monoxide (CO), and reduces nitrogen oxides (NOx). In this embodiment, a metal carrier is used as the carrier, but a ceramic carrier can also be used.

[0026] The second exhaust filter 333 is a filter medium having a mesh coarseness capable of capturing particulate matter in the exhaust gas, and can be realized by a gasoline particulate filter, similar to the first exhaust filter 331. In this embodiment, the same exhaust filters having the same dimensions and mesh coarseness are used for the first and second exhaust filters 331, 333, but different exhaust filters can also be used. The second exhaust filter 333 is capable of capturing catalyst poisoning substances derived from engine oil in addition to particulate matter.

[0027] (Exhaust filter configuration) FIG. 3 is an enlarged cross-sectional view that schematically shows the configuration of the first exhaust filter 331 and the second exhaust filter 333. As shown in FIG.

[0028] The first exhaust filter 331 is constructed using a honeycomb-shaped monolithic filter medium 331a made of ceramic such as cordierite as a base material. The interior of the filter medium 331a is separated into multiple cells c (c1, c2) by a porous wall w. Plugging materials 331b are alternately arranged on the inlet and outlet sides of adjacent cells c, forming first cells c1 that are open on the inlet side and closed on the outlet side, and second cells c2 that are open on the outlet side and closed on the inlet side, alternately separated by the porous wall w. When exhaust gas flows through the inlet side of the first exhaust filter 331, particulate matter in the exhaust gas is captured by the porous wall w as the exhaust gas passes from the first cells c1 to the second cells c2 and accumulates on the inner surface of the first cells c1. This allows particulate matter to be removed from the exhaust gas.

[0029] The first exhaust filter 331 and the second exhaust filter 333 may not only be composed of the filter medium 331a, but may also be configured such that a catalyst component is supported on the filter medium 331a. An example of a catalyst component that can be supported on the filter medium 331a is a three-way catalyst. In this embodiment, a three-way catalyst is disposed on the inner surfaces of the porous wall w that define the first and second cells c1 and c2, respectively. However, as will be described later, in consideration of the possibility that the catalytic converter 33 may be removed from the exhaust pipe 32 and then reattached to the exhaust pipe 32 in reverse, the three-way catalyst may be disposed only on the inner surfaces that define the cells that are located on the inlet side when the exhaust gas passes through. Specifically, of the first and second exhaust filters 331, 333, the first exhaust filter 331, which is closer to the inlet portion 334b ​​of the housing 334, is placed on the inner surface that defines the first cell c1 that opens toward the inlet portion 334b, and the second exhaust filter 333, which is closer to the outlet portion 334c, is placed on the inner surface that defines the second cell c2 that opens toward the outlet portion 334c.

[0030] Returning to FIG. 2, the housing 334 is cylindrical overall and includes an intermediate portion 334a and an inlet portion 334b ​​and an outlet portion 334c, which sandwich the intermediate portion 334a from the front and rear in the exhaust flow direction A. The first exhaust filter 331, the exhaust purification catalyst 332, and the second exhaust filter 333 are disposed in the intermediate portion 334a. The inlet portion 334b ​​and the outlet portion 334c are each funnel-shaped, narrowing in the direction away from the intermediate portion 334a. An inlet flange portion 334d is provided at the tip of the inlet portion 334b, and an outlet flange portion 334e is provided at the tip of the outlet portion 334c. The catalytic converter 33 is connected to the upstream exhaust pipe 32a (FIG. 1) via the inlet flange portion 334d, and to the downstream exhaust pipe 32b via the outlet flange portion 334e.

[0031] Here, the catalytic converter 33 is detachable from the exhaust pipe 32, and can be installed in reverse order. In other words, the catalytic converter 33 can be installed in the exhaust pipe 32 either in a direction in which the exhaust flows from the first exhaust filter 331 via the exhaust purification catalyst 332 to the second exhaust filter 333 (hereinafter referred to as the "forward direction"), or in a direction in which the exhaust flows from the second exhaust filter 333 via the exhaust purification catalyst 332 to the first exhaust filter 331 (hereinafter referred to as the "reverse direction"). When the exhaust flows in the forward direction, particulate matter in the exhaust is trapped by the first exhaust filter 331 and deposited on the inner surfaces of the porous walls w that define the first cells c1. On the other hand, when the exhaust flows in the reverse direction, particulate matter in the exhaust is trapped by the second exhaust filter 333 and deposited on the inner surfaces of the porous walls w that define the second cells c2.

[0032] (Outline of control system configuration) As shown in FIG. 1, the engine E includes an engine controller 101, various sensors 201 to 203, and a warning light 301.

[0033] The engine controller 101 is an electronic control unit configured as a microcomputer including a central processing unit (CPU), storage devices such as ROM and RAM, an input / output interface, and the like.

[0034] The engine E is equipped with an intake air amount sensor 201, an engine speed sensor 202, and a differential pressure sensor 203 as sensors related to the control of its operating state.

[0035] The intake air amount sensor 201 detects the flow rate of air taken into the cylinders of the engine E.

[0036] The engine speed sensor 202 detects the rotation speed of the engine E.

[0037] The differential pressure sensor 203 detects the differential pressure DIF between the exhaust pressure Pexh1 upstream of the catalytic converter 33 and the exhaust pressure Pexh2 downstream of the catalytic converter 33 (the differential pressure before and after the catalytic converter 33, hereinafter sometimes referred to as the "differential pressure before and after the filter").

[0038] The engine controller 101 controls the operating state of the engine E while controlling the air-fuel ratio of the mixture used for combustion based on the detection signals output from these various sensors 201 to 203.

[0039] (Contents of exhaust purification control) In this embodiment, while the engine E is operating, exhaust purification control is executed and the differential pressure before and after the catalytic converter 33 (i.e., the differential pressure before and after the filter DIF) is monitored. Then, when the accumulation of particulate matter in the first exhaust filter 331 progresses and the differential pressure before and after the catalytic converter 33, in other words, the pressure loss in the catalytic converter 33, increases to a certain level or more, control is executed to raise the temperature of the exhaust gas (hereinafter referred to as "exhaust temperature rise control"), and a process is executed to burn off the particulate matter accumulated in the exhaust filters, specifically, the exhaust filters 331, 333 arranged upstream of the exhaust purification catalyst 332 (hereinafter referred to as "catalyst regeneration process").

[0040] After the exhaust gas temperature increase control is executed, if the pressure difference across the catalytic converter 33 falls below a predetermined pressure, the operation of the engine E is continued. On the other hand, if the pressure difference across the catalytic converter 33 remains at or above a predetermined pressure, the operation of the engine E is continued and a monitoring and inspection process is executed.

[0041] In the monitoring and inspection process, the differential pressure before and after the catalytic converter 33 is monitored, and the driver is prompted to take appropriate measures to deal with the accumulation of ash remaining after the incineration of particulate matter. Measures that can be taken in this embodiment to deal with the accumulation of ash include a filter front-to-back swapping measure and a filter cleaning / replacement measure. The filter front-to-back swapping measure is a measure in which the catalytic converter 33 is removed from the exhaust pipe 32, and the front and back are swapped and then attached to the exhaust pipe 32. The filter cleaning / replacement measure is a measure in which the exhaust filters 331, 332 are cleaned with high-pressure water or air blowing, and if the pressure difference does not decrease sufficiently even after cleaning, the exhaust filters 331, 332 are replaced.

[0042] (Flowchart explanation) Figures 4 to 7 are flowcharts showing the flow of exhaust purification control according to this embodiment. Figure 4 shows the details of the catalyst regeneration process, and Figures 5 to 7 show the details of the monitoring and inspection process. The monitoring and inspection process is divided into a first half and a second half, with Figure 6 showing the details of the filter front-rear replacement timing notification process in the first half, and Figure 7 showing the details of the filter cleaning and replacement timing notification process in the second half. Exhaust purification control is executed by engine controller 101 at a predetermined interval after engine E is started.

[0043] In the flowchart shown in FIG. 4, in S101, various control information required for exhaust purification control is read.

[0044] In S102, the differential pressure between the exhaust pressure Pexh1 on the upstream side of the catalytic converter 33 and the exhaust pressure Pexh2 on the downstream side of the catalytic converter 33, that is, the filter differential pressure DIF, is detected.

[0045] In S103, it is detected whether the differential pressure DIF across the filter is equal to or greater than the first threshold THR1. If the differential pressure DIF across the filter is equal to or greater than the first threshold THR1, it is determined that the accumulation of particulate matter in the first and second exhaust filters 331, 332 has reached a certain level, and the increase in pressure loss will interfere with normal operation of the engine E, and the process proceeds to S104. On the other hand, if the differential pressure DIF across the filter is less than the first threshold THR1, the current control is terminated.

[0046] In S104, the warning light 301 is activated in a first predetermined mode (mode A) to prompt the driver to recognize that exhaust gas temperature increase control will be executed.

[0047] In S105, exhaust gas temperature raising control is executed. The exhaust gas temperature raising control is performed, for example, by increasing the fuel injection amount by the fuel injector 51 to increase the rotation speed of the engine E or by retarding the ignition timing by the spark plug 61.

[0048] In S106, it is determined whether a predetermined time has elapsed since the start of exhaust gas temperature increase control. If the predetermined time has elapsed, the process proceeds to S107, and if not, the processes from S104 to S106 are repeated until the predetermined time has elapsed.

[0049] In S107, the operation of the warning light 301 in the first predetermined mode is stopped.

[0050] In S108, it is detected whether the differential pressure across the filter DIF is less than a second threshold value THR2. The second threshold value THR2 is a threshold value that is smaller than the first threshold value THR1. If the differential pressure across the filter DIF is less than the second threshold value THR2, the current control is terminated. However, if it is not less than the second threshold value THR2, that is, if the differential pressure across the filter DIF maintains a pressure equal to or greater than the second threshold value THR2, it is determined that the accumulation of ash remaining after the incineration of particulate matter has not eliminated the pressure loss, and the first and second exhaust filters 331, 332 cannot be regenerated, and the process proceeds to S109.

[0051] In S109, the warning light 301 is activated in a second predetermined mode (mode B) to prompt the driver to take the measure of replacing the front and rear filters.

[0052] 5, in S201, it is determined whether or not it is immediately after the catalytic converter 33 has been attached to the exhaust pipe 32. If it is immediately after the catalytic converter 33 has been attached, the process proceeds to S202, and if not, the current control is terminated. In other words, in this embodiment, the filter front / rear switching time notification process and filter cleaning / replacement time notification process, which will be described later, are performed only immediately after the catalytic converter 33 has been removed from the exhaust pipe 32 and then reattached to the exhaust pipe 32.

[0053] In S202, a process for notifying the timing of front-rear filter replacement is performed according to the procedure shown in the flowchart of FIG. 6, and a process for notifying the timing of filter cleaning and replacement is performed according to the procedure shown in the flowchart of FIG.

[0054] In the flowchart shown in FIG. 6, in S301, the differential pressure across the filter DIF is detected.

[0055] In S302, it is determined whether or not a filter front-to-back replacement measure has been implemented, specifically, whether or not the catalytic converter 33 has been removed from the exhaust pipe 32 and reattached to the exhaust pipe 32 after the warning in the second predetermined mode. If a filter front-to-back replacement measure has been implemented, the process proceeds to S303, and otherwise, that is, if a filter front-to-back replacement measure has not been implemented, the process bypasses the processes of S303 and S304 and proceeds to S401 in the flowchart shown in FIG.

[0056] In S303, it is determined whether the differential pressure before and after the filter DIF is less than the third threshold value THR3. If the differential pressure before and after the filter DIF is less than the third threshold value THR3, the current process is terminated. However, if the differential pressure before and after the filter DIF is not less than the third threshold value THR3, that is, if the differential pressure before and after the filter DIF maintains a pressure equal to or greater than the third threshold value THR3, it is determined that a certain amount or more of ash still remains in the first and second exhaust filters 331, 332 even after the filter replacement measure, and the process proceeds to S304.

[0057] In S304, the warning light 301 is activated in a third predetermined mode (mode C) to prompt the driver to take measures to clean or replace the filter.

[0058] 7, in S401, it is determined whether or not the exhaust filters 331, 333 have been cleaned with high-pressure water or air blow (filter cleaning measures). If the filter cleaning measures have been performed, the process proceeds to S402, and if not, the process proceeds to S404.

[0059] In S402, it is determined whether the differential pressure across the filter DIF is less than a fourth threshold value THR4. If the differential pressure across the filter DIF is less than the fourth threshold value THR4, the current control is terminated. However, if the differential pressure across the filter DIF is not less than the fourth threshold value THR4, that is, if the differential pressure across the filter DIF maintains a pressure equal to or greater than the fourth threshold value THR4, it is determined that a certain amount of ash or more still remains in the first and second exhaust filters 331, 332 even after the filter cleaning procedure, and the process proceeds to S403. In this embodiment, a threshold value equal to the third threshold value THR3 is used as the fourth threshold value THR4, but a threshold value different from the third threshold value THR3 may also be used.

[0060] In S403, the warning light 301 is activated in a fourth predetermined mode (mode D) to prompt the driver to take filter replacement measures to replace the exhaust filters 331, 333 with new ones. After the warning light 401 is activated in the fourth predetermined mode, the engine controller 101 may execute engine output suppression control to suppress the emission of particulate matter from the engine E.

[0061] In S404, since it is determined that neither the front-to-rear filter replacement measures nor the filter cleaning / replacement measures have been taken yet, the warning light 301 is activated in the fifth predetermined mode (mode E) to prompt the driver to take the front-to-rear filter replacement measures.

[0062] (Explanation of action and effect) The effects obtained by this embodiment will be described below.

[0063] First, catalyst poisoning substances derived from engine oil are captured by the upstream exhaust filter (first exhaust filter 331 before the catalytic converter 33 is swapped), making it possible to prevent catalyst poisoning substances from flowing into the exhaust purification catalyst 332 and the resulting decline in exhaust purification performance.

[0064] Furthermore, if the accumulation of particulate matter in the exhaust and repeated regeneration of the exhaust filters 331, 333 causes the accumulation of ash remaining on the exhaust filters 331, 333 to increase, and the differential pressure before and after the catalytic converter 33 (i.e., the pressure loss in the catalytic converter 33) increases, the catalytic converter 33 can be removed from the exhaust pipe 32 along with the casing 334, swapped front to back, and then reattached. This will allow the exhaust pressure to remove the ash from the exhaust filter (for example, the first exhaust filter 331, which is positioned downstream after the swap), thereby restoring the filter function.

[0065] FIG. 8 is a schematic diagram showing the effect (ash removal) of swapping the catalytic converter 33. FIG. 8(a) shows the state inside the exhaust filters 331, 333 before swapping, and FIG. 8(b) shows the state inside the exhaust filters 331, 333 after swapping. In this way, as particulate matter accumulates on the exhaust filters 331, 332 and the exhaust filters 331, 332 are repeatedly regenerated by incinerating the particulate matter, the ash remaining after incineration accumulates inside the exhaust filters 331, 332. By swapping the catalytic converter 33, the cell c1 in which the ash has accumulated opens downstream after swapping, allowing the ash to be discharged by the exhaust pressure.

[0066] Furthermore, the downstream exhaust filter (the second exhaust filter 333 before the catalytic converter 33 is switched) prevents seawater from adhering to the exhaust purification catalyst 332, making it possible to prevent the exhaust purification catalyst 332 from being poisoned by calcium contained in seawater, just as with calcium contained in the exhaust.

[0067] Secondly, in the exhaust purification catalyst 332, the catalyst components are coated uniformly over the entire inner surface of the catalyst carrier, so that when the catalytic converter 33 is installed with its front and rear orientation reversed, it is possible to avoid a situation in which the distribution of the catalyst components (for example, the thickness of the coating) on ​​the inlet and outlet sides of the exhaust purification catalyst 332 is reversed, causing a disruption to the exhaust purification performance.

[0068] Third, the differential pressure before and after the catalytic converter 33 (i.e., the differential pressure before and after the filter DIF) is detected, and when the differential pressure before and after the filter DIF reaches a first threshold value THR1, exhaust temperature control is executed to burn off particulate matter accumulated on the upstream exhaust filter (the first exhaust filter 331 before the catalytic converter 33 is swapped), thereby regenerating the first exhaust filter 331 and preventing a situation in which pressure loss in the catalytic converter 33 impairs engine performance.

[0069] Fourth, after the exhaust temperature rise control is executed, the differential pressure DIF before and after the filter is maintained at a pressure equal to or greater than the second threshold THR2, thereby accurately detecting that the accumulation of ash remaining in the first and second exhaust filters 331, 333 has progressed beyond a certain level, and the warning light 301 alerts the driver to this, making it possible to appropriately urge the driver to switch the catalytic converter 33 between the front and rear.

[0070] Fifth, after switching the catalytic converter 33, if the differential pressure DIF before and after the filter is maintained at or above the third threshold value THR3 or the fourth threshold value THR4, it is detected that a certain amount of ash remains in the first and second exhaust filters 331, 332, and the warning light 301 notifies the driver of this, making it possible to appropriately prompt the driver to clean or replace the catalytic converter 33 (specifically, the exhaust filters 331, 333).

[0071] Sixth, by interposing the catalytic converter 33 in the exhaust pipe 32 so that the first and second exhaust filters 331, 333 are arranged above and below the exhaust purification catalyst 332 and the outlet or downstream end of the exhaust purification catalyst 332 faces downward, it is possible to reliably prevent seawater from adhering to the exhaust purification catalyst 332 by the downstream exhaust filter (the second exhaust filter 333 before the catalytic converter 33 is swapped).

[0072] (Description of Other Embodiments) FIG. 9 is a cross-sectional view that schematically shows the internal configuration of a catalytic converter 51 according to another embodiment of the present invention.

[0073] The catalytic converter 51 includes a first exhaust filter 511, an exhaust purification catalyst 512, and a second exhaust filter 513, and similar to the example described above, these exhaust purification elements 511, 512, and 513 are housed in a cylindrical housing 514. A water jacket j for cooling is formed in the housing 514, and seawater can be circulated through the water jacket j.

[0074] Housing 514 has intermediate portion 514a, and inlet portion 514b and outlet portion 514c that sandwich intermediate portion 514a from the front and rear in exhaust flow direction A. Inlet portion 514b and outlet portion 514c both have the same outer diameter as intermediate portion 514a. Unlike the example described above, inlet portion 514b and outlet portion 514c are not provided with enlarged diameter portions that serve as flanges, and flange-shaped end portions 321a and 321b formed on exhaust pipes 32a and 32b, respectively, abut against the end faces of inlet portion 514b and outlet portion 514c, respectively. The flange-shaped end 321a of the upstream exhaust pipe 32a is fixed to the inlet portion 514b of the housing 514 by a bolt 515a arranged to avoid the water jacket j, and the flange-shaped end 321b of the downstream exhaust pipe 32b is fixed to the outlet portion 514c of the housing 514 by a bolt 515b arranged to avoid the water jacket j. [Explanation of symbols]

[0075] E...engine, 1...engine body, 2...intake system, 3...exhaust system, 21...surge tank, 22...intake manifold, 31...exhaust manifold, 32...exhaust pipe, 33, 51...catalytic converter, 331, 511...first exhaust filter (gasoline particulate filter), 332, 512...exhaust purification catalyst, 333, 513...second exhaust filter (gasoline particulate filter).

Claims

1. an engine body having a cylinder bore centerline oriented horizontally and a piston that can reciprocate horizontally within the cylinder bore along the cylinder bore centerline; an exhaust pipe connected to the engine body so that exhaust gas after combustion can flow; an exhaust purification device installed in the exhaust pipe, The exhaust purification device is an exhaust purification catalyst having a catalyst carrier and a catalyst component that promotes an exhaust purification reaction supported on the catalyst carrier; first and second exhaust filters arranged to sandwich the exhaust purification catalyst from the front and rear in the exhaust flow direction and capable of capturing particulate matter in the exhaust; a housing that houses the exhaust purification catalyst, the first exhaust filter, and the second exhaust filter and is configured to be detachable from the exhaust pipe, After being removed from the exhaust pipe, the housing can be attached to the exhaust pipe by switching its front-to-back orientation, and can be switched between a first operating state before removal, in which exhaust flows from the first exhaust filter to the second exhaust filter via the exhaust purification catalyst, and a second operating state after attachment, in which exhaust flows from the second exhaust filter to the first exhaust filter via the exhaust purification catalyst.

2. 2. The engine of claim 1, wherein the catalytic component is uniformly coated over the entire inner surface of the catalyst support along the exhaust flow.

3. a differential pressure detection means for detecting a differential pressure between the upstream side and the downstream side of the exhaust purification device; 2. The engine according to claim 1, further comprising a filter regeneration means that, when the differential pressure exceeds a first threshold, performs exhaust temperature increase control to increase the temperature of the exhaust gas and incinerates the particulate matter that has accumulated on the first exhaust filter or the second exhaust filter.

4. 4. The engine according to claim 3, further comprising a warning unit that issues a warning to prompt the user to switch the exhaust gas purification device between upstream and downstream sides when the differential pressure remains higher than a second threshold value after the filter regeneration unit performs the exhaust gas temperature increase control.

5. 5. The engine according to claim 4, wherein the warning means issues a warning to prompt cleaning of the first and second exhaust filters or replacement of the exhaust purification device when the differential pressure after switching the front and rear of the exhaust purification device remains higher than a third threshold value.

6. 2. The engine according to claim 1, wherein the housing is interposed in the exhaust pipe so that the first and second exhaust filters are aligned vertically relative to the exhaust purification catalyst, with an exhaust inlet facing upward and an exhaust outlet facing downward.

7. The engine according to any one of claims 1 to 6, wherein the crankshaft is disposed vertically; a propeller shaft disposed in a direction intersecting the crankshaft; a power transmission mechanism configured to be able to transmit torque of the crankshaft to the propeller shaft; a propeller attached to the shaft end of the propeller shaft.

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