Abstract: A crankshaft bearing structure is provided capable of properly lubricating a thrust bearing even when low-viscosity oil is used in an engine. The crankshaft bearing structure includes a crankshaft, a cylinder block, plural journal bearings, and thrust bearings. Each of the plural journal bearings is annularly attached to a respective one of plural crank journals when the crankshaft is rotating. The thrust bearings are attached to a shaft support section, which supports the crank journal, in the cylinder block, to restrict movement of the crankshaft in a direction along an axis. The upper journal bearing annularly attached to the crank journal has a circumferential groove provided in an inner circumferential surface, connected to an oil hole, and extending in a circumferential direction.

Abstract: A crankshaft bearing structure is provided, in which a crankshaft includes a first crank journal and a second crank journal, and a crank pin disposed therebetween. First upper-and-lower journal bearings and second upper-and-lower journal bearings are attached to the respective crank journals, and each upper bearing includes an oil hole connected to an oil passage to supply oil to between the crank journal and the journal bearings. An in-shaft oil passage is formed in the crankshaft to draw oil from an outer circumferential surface of the second crank journal to an outer circumferential surface of the crank pin. The second upper journal bearing has, on an inner circumferential surface thereof, a circumferential groove connected to the oil hole. The oil is supplied to between the first upper-and-lower journal bearings and the first crank journal, only through a passage passing through the oil hole of the first upper journal bearing.

Abstract: A crankshaft bearing structure is provided, in which a crankshaft includes a first crank journal and a second crank journal, and a crank pin disposed therebetween. First upper-and-lower journal bearings and second upper-and-lower journal bearings are attached to the respective crank journals, and each upper bearing includes an oil hole connected to an oil passage to supply oil to between the crank journal and the journal bearings. An in-shaft oil passage is formed in the crankshaft to draw oil from an outer circumferential surface of the second crank journal to an outer circumferential surface of the crank pin. The second upper journal bearing has, on an inner circumferential surface thereof, a circumferential groove connected to the oil hole. The oil is supplied to between the first upper-and-lower journal bearings and the first crank journal, only through a passage passing through the oil hole of the first upper journal bearing.

Abstract: A resistance welding method according to the invention includes: a melting start time specification process for specifying a melting start time, which is a time at which at least a part of a welding portion of a welding subject starts to melt while being subjected to Joule heating by a power input from an electrode pressed against the welding subject, by detecting a variation in an ultrasonic wave emitted toward the welding portion; a first power amount calculation process for calculating a first power amount, which is an integrated value of the power input into the welding subject via the electrode from the melting start time; a first determination process for determining whether or not the first power amount has reached a first set value; and a heating process for performing the Joule heating from the melting start time until the first power amount reaches the first set value.

Abstract: In a resistance welding method, by controlling the power amount from a melting start time onward, the weld quality may be stabilized efficiently, even when a disturbance is present, because of the correlation between the amount of power input from the melting start start time and a resulting nugget. The resistance welding method includes: pressing an electrode against a workpiece; inputting power to the workpiece through the electrode to subject the workpiece to Joule heating; detecting the melting start time, which is the time at which at least a portion of the faying portion of a workpiece starts to melt when subjected to Joule heating; calculating a first power amount input into the workpiece from the melting start time; and determining whether the first power amount has reached a first set value; and continuing the Joule heating until the first power amount reaches the first set value.