Oil passage structure for hydraulic clutch of an engine

An oil passage structure for a hydraulic clutch for an engine, the hydraulic clutch being mounted on a rotational shaft having an axis parallel to a crankshaft and rotatably supported in a crankcase, the oil passage structure comprising:

• a plurality of oil passages defined in the rotational shaft and extending axially thereof, the oil passages configured to supply oil to a hydraulic clutch;
• and
• a plurality of supply oil passages configured to guide oil from an oil supply source, the supply oil passages being defined in a case cover configured to cover the hydraulic clutch and coupled to the crankcase, the supply oil passages being connected individually to the oil passages in the rotational shaft,
• wherein a cavity having a closed end wall facing an end of the rotational shaft and receiving the end of the rotational shaft therein is defined in an inner surface of the case cover such that the supply oil passages are open at inner circumferential surfaces of said cavity,
• wherein at least one radial joint hole is defined in an end portion of said rotational shaft and extends radially of said rotational shaft, the radial joint hole having an inner end connected to one of the oil passages in the rotational shaft,
• wherein said radial joint hole is connected to a corresponding one of the supply oil passages in said cavity,
• wherein the oil passage structure further comprises a cylindrical tubular member interposed between and connected to an outer circumferential surface of the end portion of said rotational shaft and an inner circumferential surface of said cavity,
• wherein said cylindrical tubular member having oil passage forming recesses defined in outer circumferential surfaces thereof independently of each other and connected individually to said supply oil passages,
• wherein an oil chamber that is connected to one of the plurality of oil passages is defined by said closed end wall of said cavity, the end of said rotational shaft, and an end of said tubular member, and
• wherein said tubular member has an axial oil hole defined therein which extends axially thereof and allowing one of the oil passage forming recesses to be connected to said oil chamber, and a radial oil hole defined therein which extends radially thereof and allowing the other oil passage forming recess to be connected to said radial joint hole.

An oil passage structure for a hydraulic clutch for an engine, the hydraulic clutch being mounted on a rotational shaft having an axis parallel to a crankshaft and rotatably supported in a crankcase, the oil passage structure, comprising:

• supplying means for supplying oil to a hydraulic clutch, the supplying means defined in the rotational shaft and extending axially thereof;
• and
• guiding means for guiding oil from an oil supply source, the guiding means being defined in a case cover means for covering the hydraulic clutch and coupled to the crankcase, the guiding means being connected individually to the supplying means in the rotational shaft;
• receiving means for receiving an end of the rotational shaft, the receiving means having a closed end wall facing an end of the rotational shaft, wherein the receiving means is defined in an inner surface of the case cover means such that the guiding means are open at inner circumferential surfaces of the receiving means,
• wherein at least one radial joint hole is defined in an end portion of said rotational shaft and extends radially of said rotational shaft, the radial joint hole having an inner end connected to one of the supplying means in the rotational shaft,
• wherein said radial joint hole is connected to a corresponding one of the guiding means in said receiving means, and
• wherein the oil passage structure further comprises cylindrical tubular member means entirely interposed between and connected to an outer circumferential surface of the end portion of said rotational shaft and an inner circumferential surface of said receiving means.

An oil passage structure for a hydraulic clutch for an engine, the hydraulic clutch being mounted on a rotational shaft having an axis parallel to a crankshaft and rotatably supported in a crankcase, the oil passage structure, comprising:

• supplying means for supplying oil to a hydraulic clutch, the supplying means defined in the rotational shaft and extending axially thereof;
• and
• guiding means for guiding oil from an oil supply source, the guiding means being defined in a case cover means for covering the hydraulic clutch and coupled to the crankcase, the guiding means being connected individually to the supplying means in the rotational shaft;
• receiving means for receiving an end of the rotational shaft, the receiving means having a closed end wall facing an end of the rotational shaft, wherein the receiving means is defined in an inner surface of the case cover means such that the guiding means are open at inner circumferential surfaces of the receiving means,
• wherein at least one radial joint hole is defined in an end portion of said rotational shaft and extends radially of said rotational shaft, the radial joint hole having an inner end connected to one of the supplying means in the rotational shaft,
• wherein said radial joint hole is connected to a corresponding one of the guiding means in said receiving means,
• wherein the oil passage structure further comprises cylindrical tubular member means interposed between and connected to an outer circumferential surface of the end portion of said rotational shaft and an inner circumferential surface of said receiving means,
• wherein cylindrical tubular member means having oil passage forming recesses defined in outer circumferential surfaces thereof independently of each other and connected individually to said guiding means,
• wherein an oil chamber that is connected to one of the supplying means is defined by said closed end wall of said receiving means, the end of said rotational shaft, and an end of said tubular member means, and
• wherein said tubular member means has an axial oil hole defined therein which extends axially thereof and allowing one of the supplying means forming recesses to be connected to said oil chamber, and a radial oil hole defined therein which extends radially thereof and allowing the other supplying means forming recess to be connected to said radial joint hole.

A method, comprising:

• supplying oil, by a plurality of oil passages, to a hydraulic clutch, the oil passages defined in a rotational shaft having an axis parallel to a crankshaft and rotatably supported in a crankcase, the oil passages extending axially of the rotational shaft;
• guiding oil, by a plurality of supply oil passages, from an oil supply source, the supply oil passages being defined in a case cover for covering the hydraulic clutch and coupled to the crankcase;
• connecting the supply oil passages individually to the oil passages in the rotational shaft;
• receiving, by a cavity, an end of the rotational shaft, the cavity having a closed end wall facing an end of the rotational shaft, and defining the cavity in an inner surface of the case cover such that the supply oil passages are open at inner circumferential surfaces of the cavity;
• defining at least one radial joint hole in an end portion of said rotational shaft, extending the at least one radial joint hole radially of said rotational shaft, and connecting an inner end of the radial joint hole to one of the oil passages in the rotational shaft;
• connecting said radial joint hole to a corresponding one of the supply oil passages in the cavity;
• and
• interposing entirely between and connecting a cylindrical tubular member to an outer circumferential surface of the end portion of said rotational shaft and an inner circumferential surface of said cavity.