A crank mechanism for the use in an in-line boxer engine has at least two diametrically opposed cylinders, that has a crankshaft and the respective pistons as well as connecting rods for each cylinder of the in-line boxer engine, with the connecting rods cooperatively connecting the pistons with the crankshaft. Each of the connecting rods encompasses a respective piston connecting portion, at one end having bushings accepting a gudgeon pin. At the other end, the central connecting rod has a one-piece crankshaft bearing portion for the crankpin whereas the forked connecting rod has a crankshaft bearing portion with two spaced limbs resultant in bifurcated crankshaft bearing portions for the crankpin. The crankshaft possesses a cylindrical central middle crankpin, that is eccentric towards the crankshaft, onto which a cylindrical outer crank pin is immediately attached at each side without crank webs.

A drive transmission device according to one embodiment of the disclosure includes: an arm having a motor that generates a rotational force; a speed reducer that is provided in the arm and has a carrier for decelerating rotation of the motor and outputting the decelerated rotation; a bucket fixed to the carrier by a reamer bolt, the reamer bolt being inserted in a bracket through hole formed in the bucket; and a resin bush provided between an internal surface of the bracket through hole and an external lateral surface of the reamer bolt. The mechanical strength of the resin bush is lower than the mechanical strength of the bucket and the mechanical strength of the reamer bolt.

A crankshaft with improved seizure resistance is provided. A crankshaft having journals 11 and pins 12 includes a compound layer containing iron and nitrogen on its surface, wherein, in the compound layer, for both the journals 11 and pins 12, the porosity area ratio of the thinner one of a region from the surface to a depth of 3.0 μm and a region across the total thickness of the compound layer is not higher than 10.0%, and both the journals 11 and pins 12 have such a surface geometry that the arithmetical mean deviation of the primary profile, Pa, is not larger than 0.090 μm.

A crankshaft with improved seizure resistance is provided. A crankshaft having journals 11 and pins 12 includes a compound layer containing iron and nitrogen on its surface, wherein, in the compound layer, for both the journals 11 and pins 12, the porosity area ratio of the thinner one of a region from the surface to a depth of 3.0 μm and a region across the total thickness of the compound layer is not higher than 10.0%, and both the journals 11 and pins 12 have such a surface geometry that the arithmetical mean deviation of the primary profile, Pa, is not larger than 0.090 μm.

A nodular iron alloy and automotive components, such as a crankshaft, are provided. The nodular iron alloy may include iron, about 2.2-3.2 wt % carbon, about 1.7-2.3 wt % silicon, about 0.2-0.6 wt % manganese, a maximum of 0.03 wt % phosphorus, a maximum of 0.02 wt % sulfur, about 0.2-0.6 wt % copper, about 0.1-0.4 wt % chromium, about 0.4-0.8 wt % nickel, about 0.15-0.45 wt % molybdenum, about 0.2-1.0 wt % cobalt, about 0.02-0.06 wt % magnesium, and a maximum of 0.002 wt % rare earth element(s). The nodular iron alloy may have a Young's modulus in the range of 175-195 GPa and an as-cast ultimate tensile strength in the range of 750-950 MPa. This alloy possesses favorable strength, stiffness and noise/vibration/harshness qualities, making it suitable in crankshaft applications. A method of forming the nodular iron alloy includes feeding a magnesium-based material into a molten iron alloy through a continuous system at a constant amount.

Embodiments are directed toward an engine. In some embodiments, the engine includes a water pump and a balancer shaft. In some embodiments, the water pump has a plain bearing. In some embodiments, plain bearing is supplied with pressurized oil. In some embodiments, the balancer shaft drives the water pump as well as cam shafts.

An automotive shaft includes a journal having a crest-to-crest contact surface area defined by and between undercut regions of the shaft, an entirety of the crest-to-crest contact surface area being laser hardened to a depth no greater than 1 mm to form a layer that does not contain unhardened portions.

A method of manufacturing a crankshaft having weight-reducing forged holes can achieve lightening and precise forming by additionally including a punching process of using an individual hydraulic press. The method includes steps of: heating a steel bar, performing busting such that the heated steel bar is disposed in a cavity of a mold to be produced as a first intermediate shape of a crankshaft, performing brokering such that the first intermediate shape is produced as a second intermediate shape, performing finishing such that the second intermediate shape is produced as a third intermediate shape, performing trimming such that the third intermediate shape is produced as a complete shape of the crankshaft by cutting portions other than the shape of the crankshaft, and performing punching such that holes are formed in the complete shape of the crankshaft.

The present invention provides a steel material which is excellent in both of the strength (particularly, fatigue strength) and the manufacturability (particularly, bending straightening properties), and thus can be used as an automobile component such as a crankshaft by being formed into a product shape, being subjected to a high strength treatment such as a nitrocarburizing treatment, and then being subjected to the bending straightening.

A compressor and a refrigeration system having the same are provided. The compressor includes a crankcase, a thrust bearing and a crankshaft. The crankcase is formed with a crankshaft hole therein and provided with a mounting protrusion at an upper end thereof. The crankshaft hole runs upward through the mounting protrusion. The thrust bearing is fitted over the mounting protrusion. The crankshaft is rotatably disposed within the crankshaft hole, has a thrust part, and is formed with an oil supply passage therein. A lower end face of the thrust part is abutted against an upper end face of the thrust bearing. A cavity is defined by the mounting protrusion, the thrust bearing and the thrust part. A through hole is formed in a peripheral wall of the crankshaft for communicating the oil supply passage with the cavity.