A bearing cap (1) is attached to a bulkhead (22) of a cylinder block (21) made of a light metal through a pair of bolts (24). The bearing cap (1) has a frame (2) made of an iron-based metal and a cast light-alloy part (3). The frame (2) has a pair of pillar parts (9) through which the bolts (24) extend and a circular-arc-shaped arch section (10). At high temperatures, the span of the pair of the bolts (24) increases due to thermal expansion of the light-alloy material, and the pair of the pillar parts (9) expand. This causes the middle part of the arch section (10) to shift upward, thereby suppressing an increase in bearing clearance.

A scroll compressor includes scroll members that are made of austempered grey iron in whole or in part. The austempering process can increases fatigue strength and toughness of a grey iron while maintaining its good machinability and vibration damping characteristics. Use of austempered grey iron scroll members allows the scroll compressor to improve its capacity, efficiency, and durability.

A rotary compressor includes: a compressing unit that includes an annular cylinder, an end plate, an annular piston which is fit in an eccentric portion of a rotation shaft, and a vane which protrudes from the inside of a vane groove of the cylinder to the inside of an operation chamber, comes into contact with the annular piston, and partitions the operation chamber into an inlet chamber and a compression chamber. The vane is formed of steel and has a diamond-like carbon layer formed on a sliding surface with respect to the annular piston. The annular piston is formed of NiCrMo cast iron to which 0.15 wt % to 0.45 wt % of phosphorus is added, or is formed of cast iron or steel and has an iron nitride layer formed on an outer circumferential surface thereof.

A cam ring and plate module for vehicle vacuum pumps in which, when an oxide layer formed through steam treatment comes into contact with a carbon or graphite material, a uniform carbon layer is stacked on the oxide layer so as to improve corrosion resistance, wear resistance, hardness and seal resistance.

A cam ring and plate module for vehicle vacuum pumps in which, when an oxide layer formed through steam treatment comes into contact with a carbon or graphite material, a uniform carbon layer is stacked on the oxide layer so as to improve corrosion resistance, wear resistance, hardness and seal resistance.

A cam ring and plate module for vehicle vacuum pumps in which, when an oxide layer formed through steam treatment comes into contact with a carbon or graphite material, a uniform carbon layer is stacked on the oxide layer so as to improve corrosion resistance, wear resistance, hardness and seal resistance.