Honda Motor Co., Ltd.

Honda Giken Kogyo Kabushiki Kaisha

Eiko Shiozaki

Yuichi Tawarada

Hodaka Mukouhara

Takashi Matsuda

Atsushi Ogasawara

Hiroyuki Kawakubo

Katsunori Takahashi

Isamu Takahashi

Kazuyuki Nakai

Sakae Mizumura

Tensei Hayashi

Hirotaka Haze

Tohru Ohshita

A power unit case for a power unit, including an internal combustion engine and a transmission, makes it possible to enhance the lubrication of a desired meshing portion of a group of transmission gears, while reducing the size of the engine. In the power unit case, a main shaft is arranged above a space between a crankshaft and a counter shaft arranged at a position substantially horizontally behind the crankshaft. A gear-ratio selecting member is arranged above a group of transmission gears on the counter shaft whose upper portion rotates toward a meshing portion between groups of transmission gears, and a lubricating projection that projects downwardly is formed in the transmission case above each of the transmission gears on the counter shaft and at a location on a ceiling surface of the transmission case where the gear-ratio selecting member is supported.

Power unit case configured to house both an engine and a transmission, and power unit including same

A starter-motor mounting structure is provided in a wall of an engine case, in which a front mounting boss is formed in a rear inclined surface of an inclined cylinder block portion that projects from a crankcase. A rear mounting boss is formed in a front wall surface of a raised portion where an upper wall of a transmission case is raised upwardly to accommodate a main shaft that is positioned higher than a counter shaft. The front mounting boss and the rear mounting boss are offset from each other in the crankshaft direction. Front and rear brackets of a starter motor are fastened to the front mounting boss and to the rear mounting boss, respectively. This arrangement enables a starter motor to be securely mounted to a power unit case with high rigidity, while enabling a reduction in the size of the internal combustion engine.

Mounting structure for supporting a starter motor on an internal combustion engine

An engine cooling apparatus includes a cooling water outlet communicating with a water jacket provided in a cylinder block and a cylinder head provided on an intake port side of the cylinder head. A thermostat switches a path for cooling water discharged from the cooling water outlet, according to a cooling water temperature. A thermostat case for the thermostat is disposed downward of a line L extended from a coupling surface between a cylinder block and a cylinder head. The thermostat case and the cooling water outlet are connected via a connecting pipe. This arrangement makes it easy to secure a space for disposing the thermostat.

Engine cooling apparatus

A lubrication system of a vehicle engine wherein a cylinder head has a head side oil passage disposed at one end thereof along the axis of a crankshaft. A lower case of a crankcase is provided with a supply source side oil passage communicating with an oil supply source and extending parallel to the axis of the crankshaft and a branched oil passage guiding oil to the head side oil passage which branches from the supply source side oil passage and extends upwardly. An upper case side oil passage extending vertically to communicate with a head side oil passage is provided at one end of an upper case along the axis of the crankshaft. A communication passage communicating the upper end of a branched oil passage is provided in a lower case in a position inwardly from the upper case side oil passage along the axis of the crankshaft.

Lubrication system of small vehicle engine

A vehicular power unit including a drive-side transmission sprocket wheel provided on an end of an output shaft that protrudes from one side of a crankcase, an endless transmission belt for transmitting power to a driving wheel wound the sprocket wheel. The endless transmission belt transmits power from the crankshaft to a transmission housed in the crankcase. A water pump is arranged on the same side of the crankcase in a position between the crankshaft and the output shaft. Further, the water pump is disposed inside the drive-side transmission sprocket wheel in a direction along the axis of an output shaft. This configuration enables the vehicular power unit to be formed in a compact size in a direction along an axis of a crankshaft.

Vehicular power unit

A water pump is provided on one lower side of a crankcase and connected to a water jacket on the rear surface of the cylinder block through a water hose. The outlet section of the water jacket is connected to the thermostat case near this connecting section. The thermostat valve is a bottom bypass type thermostat valve, directly attached to the rear surface of the cylinder head. The bypass hose is connected to the water pump and passes along the side of a starter motor and passes between the starter motor and a speed sensor. The arrangement of the bypass hose in a bottom bypass type thermostat valve effectively utilizes space.

Water-cooled engine

A starter motor and balancers are disposed reasonably so as not to interfere with each other by effectively utilizing spaces in an engine. Cylinders are set so as to be tilted forward on casings supporting a crankshaft in a transverse position, a rear balancer and a starter motor are disposed in a space behind the cylinders, and a front balancer is disposed on an opposite side of the rear balancer with respect to the crankshaft. The rear balancer and the front balancer are disposed on the right side of a plane including the center of gravity of the engine and perpendicular to the crankshaft, and the starter motor is disposed on the left side of the plane. Weight portions included in the rear balancer and the front balancer are disposed close to the plane to prevent coupling vibrations.

Growing community of inventors

Saitama, Japan

Eiko Shiozaki