Abstract: For example, two intake valves for each cylinder each are driven by a selected one of cams via a corresponding rocker arm. Each rocker arm includes a support portion and a pressing portion (distal end portion). The support portion is rockably supported by a cylinder head. The pressing portion is configured to press a stem of the corresponding intake valve. The support portion of one of the rocker arms deviates to one side in an axis X direction (cam axial direction) with respect to the distal end portion. The support portion of the other one of the rocker arms deviates to the other side in the axis X direction with respect to the distal end portion.

Abstract: A variable valve mechanism includes a camshaft and a cam unit. Internal spline teeth provided at an inner periphery of a sleeve of the cam unit are in mesh with external spline teeth provided at an outer periphery of the camshaft. An engaging portion is provided at one of the inner periphery of the sleeve and the outer periphery of the camshaft, and is configured to retractably project toward the other one of the inner periphery of the sleeve and the outer periphery of the camshaft. A latching portion is provided at the other one of the inner periphery of the sleeve and the outer periphery of the camshaft. The sleeve has a through-hole that is provided at the same position in a circumferential direction as the engaging portion to supply the inner periphery of the sleeve with lubricating oil.

Abstract: A variable valve mechanism includes a first cam unit including cams configured to drive an intake valve on a first side in a first cylinder; a first sliding mechanism configured to slide the first cam unit such that the first cam unit is switched between two positions to select any one of the cams; a second cam unit including cams configured to drive an intake valve on a second side in the first cylinder, cams configured to drive an intake valve on the first side in a second cylinder, and cams configured to drive an intake valve on the second side in the second cylinder; and a second sliding mechanism configured to slide the second cam unit such that the second cam unit is switched among three positions to select any one of the cams for each of the intake valves.

Abstract: A first swing arm of each cylinder is swung by a fixed cam of an intake camshaft, so as to operate a first intake valve according to a profile thereof. A second swing arm is swung by a second cam and its swing range is changed by a variable mechanism. Hereby, a lift amount of a second intake valve changes continuously. The second cam is selected from a plurality of cams on a cam piece provided around the intake camshaft.

Abstract: A variable valve mechanism includes a cam shaft, a cam unit, a guide portion and a shift pin. The guide portion includes a guide plate provided on an outer periphery of a cam unit, a first stopper and a second stopper. The guide plate is pivotally supported at a first part such that a second part of the guide plate is inclined toward a first side or a second side. The first and second stoppers abut with the second part from the first side and the second side, respectively, so as to hold the second part at a first position and a second position, respectively. The first part includes two arms projecting toward the first side and the second side. The two arms are configured to swing the guide plate.

Abstract: A variable valve mechanism includes a camshaft and a cam unit. Internal spline teeth provided at an inner periphery of a sleeve of the cam unit are in mesh with external spline teeth provided at an outer periphery of the camshaft. An engaging portion is provided at one of the inner periphery of the sleeve and the outer periphery of the camshaft, and is configured to retractably project toward the other one of the inner periphery of the sleeve and the outer periphery of the camshaft. A latching portion is provided at the other one of the inner periphery of the sleeve and the outer periphery of the camshaft. The sleeve has a through-hole that is provided at the same position in a circumferential direction as the engaging portion to supply the inner periphery of the sleeve with lubricating oil.

Abstract: For example, two intake valves for each cylinder each are driven by a selected one of cams via a corresponding rocker arm. Each rocker arm includes a support portion and a pressing portion (distal end portion). The support portion is rockably supported by a cylinder head. The pressing portion is configured to press a stem of the corresponding intake valve. The support portion of one of the rocker arms deviates to one side in an axis X direction (cam axial direction) with respect to the distal end portion. The support portion of the other one of the rocker arms deviates to the other side in the axis X direction with respect to the distal end portion.

Abstract: In a variable valve mechanism, a guide groove includes guide portions provided on respective side surfaces of the guide groove in a width direction, the guide portions projecting so as to face each other; a cam unit is slid toward a first side by relatively moving a shift pin toward a second side with use of the guide portion on the first side, and the cam unit is slid toward the second side by relatively moving the shift pin toward the first side with use of the guide portion on the second side; the guide portion on the first side is provided in an immovable piece, and the guide portion on the second side is provided in a movable piece; the movable piece is displaceable between a first position and a second position: and a first urging member configured to urge the movable piece toward the first position is provided.

Abstract: A first swing arm of each cylinder is swung by a fixed cam of an intake camshaft, so as to operate a first intake valve according to a profile thereof. A second swing arm is swung by a second cam and its swing range is changed by a variable mechanism. Hereby, a lift amount of a second intake valve changes continuously. The second cam is selected from a plurality of cams on a cam piece provided around the intake camshaft.

Abstract: A variable valve mechanism includes a first cam unit including cams configured to drive an intake valve on a first side in a first cylinder; a first sliding mechanism configured to slide the first cam unit such that the first cam unit is switched between two positions to select any one of the cams; a second cam unit including cams configured to drive an intake valve on a second side in the first cylinder, cams configured to drive an intake valve on the first side in a second cylinder, and cams configured to drive an intake valve on the second side in the second cylinder; and a second sliding mechanism configured to slide the second cam unit such that the second cam unit is switched among three positions to select any one of the cams for each of the intake valves.

Abstract: A variable valve mechanism includes a cam shaft, a cam unit, a guide portion and a shift pin. The guide portion includes a guide plate provided on an outer periphery of a cam unit, a first stopper and a second stopper. The guide plate is pivotally supported at a first part such that a second part of the guide plate is inclined toward a first side or a second side. The first and second stoppers abut with the second part from the first side and the second side, respectively, so as to hold the second part at a first position and a second position, respectively. The first part includes two arms projecting toward the first side and the second side. The two arms are configured to swing the guide plate.

Abstract: In a variable valve mechanism, a guide groove includes guide portions provided on respective side surfaces of the guide groove in a width direction, the guide portions projecting so as to face each other; a cam unit is slid toward a first side by relatively moving a shift pin toward a second side with use of the guide portion on the first side, and the cam unit is slid toward the second side by relatively moving the shift pin toward the first side with use of the guide portion on the second side; the guide portion on the first side is provided in an immovable piece, and the guide portion on the second side is provided in a movable piece; the movable piece is displaceable between a first position and a second position: and a first urging member configured to urge the movable piece toward the first position is provided.