Off-road vehicle and engine thereof

An off-road vehicle comprising:

• a frame;
• a pair of front wheels;
• a pair of rear wheels;
• a controller;
• a suspension system, comprising a front suspension and a rear suspension, the front wheels being connected to the frame by the front suspension, and the rear wheels being connected to the frame by the rear suspension;
• an engine supported on the frame, at least one of the front or rear wheels being rotationally driven by the engine, the engine being equipped with a combustion chamber, the engine comprising a cylinder block and a cylinder head connected to the cylinder block, the cylinder head being equipped with air intake passage and an exhaust passage;
• a fuel supply system for supplying fuel to the engine;
• an exhaust system comprising an exhaust conduit and a muffler communicating with the exhaust conduit, the exhaust conduit communicating with the exhaust passage in the cylinder head;
• an intake system through which air is fed into the air intake passage;
• and
• a supplementary air supply passage for mixing air into the exhaust gas discharged from the combustion chamber;
• wherein an angle between a center line of the supplementary air supply passage and a center line of the exhaust passage is greater than or equal to 90°, and further comprising an air flow buffer zone in fluid communication between the supplementary air supply passage and the exhaust passage, the air flow buffer zone having a greater cross-sectional area than the supplementary air supply passage.

An off-road vehicle comprising:

• a frame;
• a pair of front wheels;
• a pair of rear wheels;
• a controller;
• a suspension system, comprising a front suspension and a rear suspension, the front wheels being connected to the frame by the front suspension, and the rear wheels being connected to the frame by the rear suspension;
• an engine supported on the frame, at least one of the front or rear wheels being rotationally driven by the engine, the engine being equipped with a combustion chamber, the engine comprising a cylinder block and a cylinder head connected to the cylinder block, the cylinder head being equipped with air intake passage and an exhaust passage;
• a fuel supply system for supplying fuel to the engine;
• an exhaust system comprising an exhaust conduit and a muffler communicating with the exhaust conduit, the exhaust conduit communicating with the exhaust passage in the cylinder head;
• an intake system through which air is fed into the air intake passage;
• and
• a supplementary air supply passage for mixing air into the exhaust gas discharged from the combustion chamber;
• wherein the supplementary air supply passage is defined in the cylinder head, and wherein the cylinder head further defines a cooling water passage, a plurality of cavities for mounting valve springs, a lubricating oil chamber and an intake passage, and the supplementary air supply passage is independent of and not in fluid communication with the cooling water passage or the lubricating oil chamber, and wherein a barrier portion of the cylinder head is arranged between the cooling water passage and the supplementary air supply passage.

An off-road vehicle comprising:

• a frame;
• a pair of front wheels;
• a pair of rear wheels;
• a controller;
• a suspension system, comprising a front suspension and a rear suspension, the front wheels being connected to the frame by the front suspension, and the rear wheels being connected to the frame by the rear suspension;
• an engine supported on the frame, at least one of the front or rear wheels being rotationally driven by the engine, the engine being equipped with a combustion chamber, the engine comprising a cylinder block and a cylinder head connected to the cylinder block, the cylinder head being equipped with air intake passage and an exhaust passage;
• a fuel supply system for supplying fuel to the engine;
• an exhaust system comprising an exhaust conduit and a muffler communicating with the exhaust conduit, the exhaust conduit communicating with the exhaust passage in the cylinder head;
• and
• an intake system through which air is fed into the air intake passage;
• and
• a supplementary air supply passage for mixing air into the exhaust gas discharged from the combustion chamber;
• wherein the engine is a multi-cylinder engine comprising a front cylinder and a rear cylinder, with a front supplementary air supply pipe corresponding to the front cylinder of the engine and a rear supplementary air supply pipe corresponding to the rear cylinder of the engine, and further comprising at least one throttling plug throttling air flow through the front supplementary air supply pipe or the rear supplementary air supply pipe.

An off-road vehicle comprising:

• a frame;
• a pair of front wheels;
• a pair of rear wheels;
• a controller;
• a suspension system, comprising a front suspension and a rear suspension, the front wheels being connected to the frame by the front suspension, and the rear wheels being connected to the frame by the rear suspension;
• an engine supported on the frame, at least one of the front or rear wheels being rotationally driven by the engine, the engine being equipped with a combustion chamber, the engine comprising a cylinder block and a cylinder head connected to the cylinder block, the cylinder head being equipped with air intake passage and an exhaust passage;
• a fuel supply system for supplying fuel to the engine;
• an exhaust system comprising an exhaust conduit and a muffler communicating with the exhaust conduit, the exhaust conduit communicating with the exhaust passage in the cylinder head;
• and
• an intake system through which air is fed into the air intake passage;
• and
• a supplementary air supply passage for mixing air into the exhaust gas discharged from the combustion chamber;
• wherein the engine is a multi-cylinder engine comprising a front cylinder and a rear cylinder, with a front supplementary air supply pipe corresponding to the front cylinder of the engine and a rear supplementary air supply pipe corresponding to the rear cylinder of the engine, wherein internal diameters of the front supplementary air supply pipe and rear supplementary air supply pipe are different.

An off-road vehicle comprising:

• a frame;
• a pair of front wheels;
• a pair of rear wheels;
• a controller;
• a suspension system, comprising a front suspension and a rear suspension, the front wheels being connected to the frame by the front suspension, and the rear wheels being connected to the frame by the rear suspension;
• an engine supported on the frame, at least one of the front or rear wheels being rotationally driven by the engine, the engine being equipped with a combustion chamber, the engine comprising a cylinder block and a cylinder head connected to the cylinder block, the cylinder head being equipped with air intake passage and an exhaust passage;
• a fuel supply system for supplying fuel to the engine;
• an exhaust system comprising an exhaust conduit and a muffler communicating with the exhaust conduit, the exhaust conduit communicating with the exhaust passage in the cylinder head;
• an intake system through which air is fed into the air intake passage;
• and
• a supplementary air supply passage for mixing air into the exhaust gas discharged from the combustion chamber;
• wherein the engine is a multi-cylinder engine comprising a front cylinder and a rear cylinder, wherein the exhaust conduit comprises a front cylinder exhaust conduit and a rear cylinder exhaust conduit joining the front cylinder exhaust conduit at a merge section, and wherein the exhaust system comprises at least a front first-stage catalytic converter in the front cylinder exhaust conduit, a rear first-stage catalytic converter is the rear cylinder exhaust conduit, and at least one second-stage catalytic converter downstream of the merge section.

An off-road vehicle comprising:

• a frame;
• a pair of front wheels;
• a pair of rear wheels;
• a controller;
• a suspension system, comprising a front suspension and a rear suspension, the front wheels being connected to the frame by the front suspension, and the rear wheels being connected to the frame by the rear suspension;
• an engine supported on the frame, at least one of the front or rear wheels being rotationally driven by the engine, the engine being equipped with a combustion chamber, the engine comprising a cylinder block and a cylinder head connected to the cylinder block, the cylinder head being equipped with air intake passage and an exhaust passage;
• a fuel supply system for supplying fuel to the engine;
• an exhaust system comprising an exhaust conduit and a muffler communicating with the exhaust conduit, the exhaust conduit communicating with the exhaust passage in the cylinder head;
• an intake system through which air is fed into the air intake passage;
• and
• a supplementary air supply passage for mixing air into the exhaust gas discharged from the combustion chamber;
• wherein the exhaust conduit comprises at least one joint sealed by a graphite seal sleeve, and wherein the graphite seal sleeve comprises copper wires and a graphite layer coated on the copper wires.

An off-road vehicle comprising:

• a frame;
• a pair of front wheels;
• a pair of rear wheels;
• a controller;
• a suspension system, comprising a front suspension and a rear suspension, the front wheels being connected to the frame by the front suspension, and the rear wheels being connected to the frame by the rear suspension;
• an engine supported on the frame, at least one of the front or rear wheels being rotationally driven by the engine, the engine being equipped with a combustion chamber, the engine comprising a cylinder block and a cylinder head connected to the cylinder block, the cylinder head being equipped with air intake passage and an exhaust passage;
• a fuel supply system for supplying fuel to the engine, wherein the fuel supply system comprises:
• a fuel tank;
• a carbon canister connected to the fuel tank;
• a carbon canister control valve connected to the carbon canister and controlling flow of air/fuel mixture from the carbon canister to the engine for combustion;
• and
• a controller electronically communicating with the carbon canister control valve for opening and/or closing the carbon canister control valve;
• an exhaust system comprising an exhaust conduit and a muffler communicating with the exhaust conduit, the exhaust conduit communicating with the exhaust passage in the cylinder head;
• an intake system through which air is fed into the air intake passage;
• and
• a supplementary air supply passage for mixing air into the exhaust gas discharged from the combustion chamber.