Patent ID: 8701849

Claim:
A hydraulic clutch for an engine, the hydraulic clutch being disposed on a rotational shaft having an axis parallel to a crankshaft and rotatably supported in a crankcase, the hydraulic clutch comprising: a clutch piston configured to selectively switch between an engaged state and a disengaged state in response to axial movement thereof, wherein said clutch piston comprises opposite surfaces facing a control hydraulic pressure chamber and a canceler chamber, respectively; at least one control oil passage connected to said control hydraulic pressure chamber; and a lubrication oil passage, connected to said canceler chamber, configured to supply lubricating oil to lubricated parts around said rotational shaft, wherein said lubricating oil passage comprises an upstream oil passage defined coaxially in said rotational shaft configured to supply lubricating oil to the lubricated parts around the rotational shaft, and a downstream oil passage connected to said upstream oil passage configured to supply lubricating oil from said upstream oil passage to said canceler chamber, wherein said downstream oil passage is smaller in diameter than said upstream oil passage and has at least a portion extending parallel to the axis of said rotational shaft, and wherein said control oil passage has an axis parallel to the axis of said rotational shaft and is defined in said rotational shaft such that at least a portion of said control oil passage is disposed in a range wherein said downstream oil passage is provided in a direction along the axis of said rotational shaft.