Crankshaft for opposed multi-cylinder reciprocating compressors

Compressor crankshaft with reduced unbalanced moments using a pair of 180-degree phase-shifted counterweights

This technology is a crankshaft for opposed multi-cylinder reciprocating compressors. It consists of four crankpins with a 90-degree phase difference or six crankpins with a 60-degree phase difference, webs connecting them to the main journal, and a pair of counterweights coupled to both ends of the main journal with a 180-degree phase difference. The counterweights are positioned away from the crankpins and are determined to satisfy the design equation between the centrifugal force of the rotating members and the centrifugal force of the counterweights.

Large reciprocating compressors used in industrial, marine, and HVAC applications have historically suffered from severe vibration due to unbalanced forces and moments generated during the conversion of rotational motion into reciprocating motion. While research into counterweight design and crankshaft geometry exists, there has been a lack of design solutions that minimize moments while reducing counterweight mass for multi-cylinder opposed structures.

This technology reduces unbalanced moments in opposed compressors by using a pair of counterweights at both ends of the main journal in opposite directions, which also reduces the number and size of the counterweights. Applicable to process gas compressors for petrochemical plants, ships, and large refrigeration systems, it reduces vibration and rotating mass, thereby extending bearing life and maintenance intervals.

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Key Features:

• Opposed multi-cylinder reciprocating compressor crankshaft equipped with four crankpins forming a 90-degree phase difference or six crankpins forming a 60-degree phase difference
• Crankshaft body structure that transmits rotational motion, including a plurality of webs connecting the crankpins and the main journal
• A pair of counterweights spaced apart from the crankpins, coupled to both ends of the main journal, and having a 180-degree phase difference from each other
• Balancing conditions that satisfy the design equation between crankpin distance, centrifugal force of rotating members, centrifugal force of counterweights, and phase angles during the reciprocating motion of the piston, piston rod, crosshead, and connecting rod

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