Abstract: [Task] A task is to improve the flexibility for setting a muffler and making a V-type engine compact. [Solution] A V-type engine (1) includes an engine body (3) including a crankcase (7) configured to rotatably support a crankshaft (11), and a first and second cylinder banks (8, 9) extending from the crankcase (7), a first exhaust pipe (41) connected to the first cylinder bank (8); a second exhaust pipe (42) connected to the second cylinder bank (9); a merging pipe connected to the first and second exhaust pipes (41, 42); a first catalyst (32a) accommodated in the first exhaust pipe (41); a second catalyst (32b) accommodated in the second exhaust pipe (42); and a muffler (33) detachably connected to the merging pipe, wherein the first catalyst (32a) is arranged along an outer surface of the first cylinder bank (8), and the second catalyst (32b) is arranged along an outer surface of the second cylinder bank (9).

Abstract: A work machine that smooths a road surface by rotating a blade contacting the road surface, the work machine comprises: a motor that rotates the blade; and a fan that cools the motor and is provided between the motor and the blade.

Abstract: An automatic choke device of a carburetor includes a wax attached to an engine main body, a rod configured to perform a linear motion in conjunction with expansion of the wax, a choke lever configured to rotate in conjunction with the linear motion of the rod, and a choke shaft arranged so as to be able to abut against the choke lever and connected to a choke valve of the carburetor. The choke lever includes a flat portion that engages with an engaging portion of the choke shaft, and a circular arc portion that is formed in a circular arc shape so as to be continuous from the flat portion and is brought into sliding contact with the engaging portion of the choke shaft.

Abstract: An engine (E) includes a crankcase body (19), a crankcase cover (20) covering a case opening portion (19b) of the crankcase body (19), a crankshaft (2), a cylinder base portion 21a located inside the crankcase body (19), a cylinder block (21b) located outside the crankcase body (19). The crankcase cover (20) is detachably attached to an upper portion of the crankcase body (19).

Abstract: An engine (E) includes a crankcase body (19) including a bottom plate (19a) and a tubular portion (19c), a crankcase cover (20) covering a case opening portion (19b) of the crankcase body (19), a crankshaft (2), a cylinder base portion (21a) located inside the crankcase body (19), a cylinder block (21b) located outside the crankcase body (19), and a camshaft (25) located inside the crankcase body (19) and between the bottom plate (19a) and cylinder base portion (21a). The crankcase body (19) has the bottom plate (19a) detachably attached to the tubular portion (19c).

Abstract: An engine (E) includes a crankcase body (19) including a bottom plate (19a) and a tubular portion (19c), a crankcase cover (20) covering a case opening portion (19b) of the crankcase body (19), a crankshaft (2), a cylinder base portion (21a) located inside the crankcase body (19), a cylinder block (21b) located outside the crankcase body (19), and a camshaft (25) located inside the crankcase body (19) and between the bottom plate (19a) and cylinder base portion (21a). The crankcase body (19) has the bottom plate (19a) detachably attached to the tubular portion (19c).

Abstract: An automatic choke device of a carburetor includes a wax attached to an engine main body, a rod configured to perform a linear motion in conjunction with expansion of the wax, a choke lever configured to rotate in conjunction with the linear motion of the rod, and a choke shaft arranged so as to be able to abut against the choke lever and connected to a choke valve of the carburetor. The choke lever includes a flat portion that engages with an engaging portion of the choke shaft, and a circular arc portion that is formed in a circular arc shape so as to be continuous from the flat portion and is brought into sliding contact with the engaging portion of the choke shaft.

Abstract: An engine is provided with: a crank case that has a first crank shaft insertion hole and a second crank shaft insertion hole along the vertical direction; a crank shaft that is inserted into the first and second shaft insertion holes; and a cylinder unit that extends in the front-rear direction from the crank case. The cylinder unit is provided with a cylinder base that is positioned inside the crank case, and a cylinder block that is positioned outside the crank case. The cylinder unit is detachably attached to the crank case.

Abstract: An engine (E) includes a crankcase body (19), a crankcase cover (20) covering a case opening portion (19b) of the crankcase body (19), a crankshaft (2), a cylinder base portion 21a located inside the crankcase body (19), a cylinder block (21b) located outside the crankcase body (19). The crankcase cover (20) is detachably attached to an upper portion of the crankcase body (19).

Abstract: A valve operating system for an internal combustion engine, which includes a decompression cam member (47) that is supported on a camshaft (26) and that operates an exhaust valve operating member (29e) in an opening direction of an exhaust valve (17e) in a compression stroke when the engine is started, an exhaust gas recirculation cam member (48) that is supported on the camshaft (26) and that operates the exhaust valve operating member (29e) in the opening direction of the exhaust valve (17e) in an intake stroke when the engine is running at high speed, and a centrifugal mechanism (46) that is mounted on a driven timing rotating member (32) rotating integrally with the valve operating cam (25) and makes the decompression cam member (47) and the exhaust gas recirculation cam member (48) move, wherein the valve operating cam (25) is provided with a recess (39) surrounding the camshaft (26), the recess (39) opening on the face on the other side of the driven timing rotating member (32) and on a base face of the

Abstract: In an exhaust emission control system for an internal combustion engine, an exhaust gas recirculation device that operates so as to partially open an exhaust valve to introduce exhaust gas into a cylinder in an intake stroke is provided; a secondary air passage capable of supplying secondary air to an exhaust passage is connected to the exhaust passage; and a one-way valve opened by negative pressure applied from the cylinder to the exhaust passage following an operation of the exhaust gas recirculation device in the intake stroke is provided in the secondary air passage. Accordingly, it is possible to provide an exhaust emission control system for an internal combustion engine that allows secondary air to be supplied into an exhaust passage to reduce HC and CO concentrations and also a NOx concentration in an exhaust gas without using an air pump regardless of an exhaust system structure of the internal combustion engine.

Abstract: A valve operating system for an internal combustion engine, which includes a decompression cam member (47) that is supported on a camshaft (26) and that operates an exhaust valve operating member (29e) in an opening direction of an exhaust valve (17e) in a compression stroke when the engine is started, an exhaust gas recirculation cam member (48) that is supported on the camshaft (26) and that operates the exhaust valve operating member (29e) in the opening direction of the exhaust valve (17e) in an intake stroke when the engine is running at high speed, and a centrifugal mechanism (46) that is mounted on a driven timing rotating member (32) rotating integrally with the valve operating cam (25) and makes the decompression cam member (47) and the exhaust gas recirculation cam member (48) move, wherein the valve operating cam (25) is provided with a recess (39) surrounding the camshaft (26), the recess (39) opening on the face on the other side of the driven timing rotating member (32) and on a base face of the

Abstract: An exhaust gas reflux mechanism for a multipurpose engine includes an exhaust reflux cam formed as an integral part of an single cam of the engine and having a cam lobe profiled to open an exhaust valve while an intake valve stays open during the intake stroke of the engine so that part of an exhaust gas remaining on the side of an exhaust port of the engine is drawn into a combustion chamber during the intake stroke.

Abstract: An exhaust gas reflux mechanism for a multipurpose engine includes an exhaust reflux cam formed as an integral part of an single cam of the engine and having a cam lobe profiled to open an exhaust valve while an intake valve stays open during the intake stroke of the engine so that part of an exhaust gas remaining on the side of an exhaust port of the engine is drawn into a combustion chamber during the intake stroke.

Abstract: In an exhaust emission control system for an internal combustion engine, an exhaust gas recirculation device that operates so as to partially open an exhaust valve to introduce exhaust gas into a cylinder in an intake stroke is provided; a secondary air passage capable of supplying secondary air to an exhaust passage is connected to the exhaust passage; and a one-way valve opened by negative pressure applied from the cylinder to the exhaust passage following an operation of the exhaust gas recirculation device in the intake stroke is provided in the secondary air passage. Accordingly, it is possible to provide an exhaust emission control system for an internal combustion engine that allows secondary air to be supplied into an exhaust passage to reduce HC and CO concentrations and also a NOx concentration in an exhaust gas without using an air pump regardless of an exhaust system structure of the internal combustion engine.

Abstract: A carburetor choke valve electronic control system includes: a transmission device coupled to a choke valve for opening and closing an intake path of a carburetor; an electric motor for driving the choke valve to be opened and closed via the transmission device; and an electronic control unit for controlling operation of the electric motor. The system further includes: a casing mounted on one side of the carburetor, and housing the transmission device and the electric motor; an operating lever disposed outside the casing; and a choke valve forced closure mechanism that allows the transmission device to be operated in a direction that closes the choke valve by operation of the operating lever.

Abstract: A carburetor choke valve electronic control system includes: a transmission device coupled to a choke valve for opening and closing an intake path of a carburetor; an electric motor for driving the choke valve to be opened and closed via the transmission device; and an electronic control unit for controlling operation of the electric motor. The system further includes: a casing mounted on one side of the carburetor, and housing the transmission device and the electric motor; an operating lever disposed outside the casing; and a choke valve forced closure mechanism that allows the transmission device to be operated in a direction that closes the choke valve by operation of the operating lever.

Abstract: A carburetor electronic control system includes: transmission devices coupled to valves for opening and closing an intake path of a carburetor; electric motors that make the valves open and close via the transmission devices; and an electronic control unit for controlling the operation of the electric motors. The interior of a casing joined to one side face of the carburetor is divided by a partition plate into a transmission chamber on the carburetor side and a drive chamber on the opposite side. The transmission devices and the electric motors are housed and held in the transmission chamber and the drive chamber, respectively. Therefore, the transmission devices, the electric actuators, and the electronic control unit can be housed in a common casing, thereby reducing the dimensions of the carburetor electronic control system.

Abstract: A valve operating system includes: a decompression cam member that is provided on a camshaft, and moves between an operative position C where an exhaust tappet is operated in a valve opening direction in a compression stroke and an inoperative position D where the exhaust tappet is released; an exhaust gas recirculation cam member that is provided on the camshaft, and moves between an inoperative position F where the exhaust tappet is released and an operative position G where the exhaust tappet is operated in a valve opening direction in an intake stroke of the engine; and a common centrifugal mechanism that is driven by the camshaft to operate the decompression cam member to the operative position C in a starting rotation region of the engine and to the inoperative position D after the starting, and operate the exhaust gas recirculation cam member to the inoperative position F in a low speed operation region of the engine and to the operative position G in a high-speed operation region.

Abstract: A carburetor choke valve electronic control system includes: a transmission device coupled to a choke valve for opening and closing an intake path of a carburetor; an electric motor for driving the choke valve to be opened and closed via the transmission device; and an electronic control unit for controlling operation of the electric motor. The system further includes: a casing mounted on one side of the carburetor, and housing the transmission device and the electric motor; an operating lever disposed outside the casing; and a choke valve forced closure mechanism that allows the transmission device to be operated in a direction that closes the choke valve by operation of the operating lever.