Abstract: In a horizontally opposed type internal combustion engine, to enable rigid support of a middle journal of a crankshaft through rational utilization of first and second case halves constituting a crankcase, and to thereby contribute to a simplification in structure and a reduction in weight. In a horizontally opposed type internal combustion engine, a crankcase is split at a plane containing the axis line of a crankshaft into first and second case halves connected with first and second cylinder blocks. The first and second case halves are integrally provided with first and second journal supporting walls for supporting a middle journal of the crankshaft. The first and second journal supporting walls front cylinder bores of the first and second cylinder blocks. The first and second journal supporting walls are coupled by a plurality of first bolts inserted from the side of the cylinder bores of the first cylinder block and disposed on opposite sides of and in proximity to the middle journal.

Abstract: In a valve system for a OHV horizontally-opposed, four-cycle internal combustion engine, valve camshafts are provided at crankcase portions for supporting a crankshaft, of left and right cylinder banks disposed on opposite sides of the crankshaft. Intake and exhaust valves are provided at cylinder heads and are opened and closed by pull rods operated by the valve camshafts. The aforementioned valve system achieves large reductions in the size and weight of the piston heads where the intake and exhaust valves of the internal combustion engine are disposed.

Abstract: An intake system for a horizontally opposed type internal combustion engine can contribute to an improvement in output performance without sacrificing the intrinsic merit of the horizontally opposed type internal combustion engine. Specifically, the intake system ensures that the overall height of the engine remains small. First and second intake ports are provided at head portions of first and second banks, which are arranged on the left and right sides. First and second intake distribution ports are arranged horizontally at a front wall of an intake surge tank 10, which is disposed on the rear end side of and adjacent to a crankshaft 1. The first and second intake ports are respectively connected with each other through first and second intake pipes disposed along a top surface or bottom surface of the engine E. Throttle valves for controlling intake quantities in the first and second intake pipes are provided in upstream portions of the intake pipes.

Abstract: To provide a valve system for an engine, in which a rocker arm is interlocked with an engine valve and is supported on a rocker shaft fixedly mounted to a cylinder head such that it is rockable with the rotation of a camshaft. Accordingly, the size and weight of the engine can be reduced. The posture of a rocker shaft is set to have an axial line crossing an axial line of a crankshaft on the projection plane perpendicular to an axial line of a cylinder bore. A rocker arm is rockably supported by the rocker shaft and is provided with an input arm extending, on the above projection plane, from the rocker arm to the camshaft side. A pull rod reciprocates in the axial direction with the rotation of the camshaft and is connected to the input arm.

Abstract: A valve actuating mechanism for an internal combustion engine in which a rotatable cam has its camming surface disposed to slide on a cam slipper surface of a rocker arm to thereby open and close an intake valve (or exhaust valve) of the engine by rocking motion of the rocker arm. The dimensions, shapes, and relative positions of the rotatable cam and the rocker arm are so designed as to satisfy a condition of V.sub.C +V.sub.F >0, where V.sub.C represents the velocity of movement of a contact point on the camming surface at which the camming surface slides on the cam slipper surface, and V.sub.F the velocity of movement of the contact point on the cam slipper surface at which the cam slipper surface slides on the camming surface.

Abstract: A slow flow meter having a free piston slideably mounted in a cylinder with a non-contact type detector measuring movement of the same. A bypass is provided between fluid inflow and outflow pipes connected to opposite ends of the cylinder. A forcible returning device is operatively associated with the bypass controller to return the free piston to its original position after measurement.