Scroll compressor

A scroll compressor comprising:

• a fixed scroll having an outlet port;
• a movable scroll engaged with the fixed scroll, the movable scroll having a movable-scroll end plate with a back surface;
• two compression chambers formed by the movable scroll engaged together with the fixed scroll, the fixed scroll and the movable scroll being configured to compress a fluid in each compression chamber by driving the movable scroll;
• a pressing mechanism including
• a back-pressure chamber facing the back surface of the movable-scroll end plate of the movable scroll, and
• a back-pressure supply path arranged to move to opposite inner and outer sides of a stationary lap of the stationary scroll as the movable scroll is driven in order to allow the back-pressure chamber to alternately communicate with one of the compression chambers when the one of the compression chambers is in
• a state right before the one of the compression chambers communicates with the outlet port and
• a state in which the one of the compression chambers communicates with the outlet port,
• the pressing mechanism being configured to press the movable scroll against the fixed scroll by internal pressure of the back-pressure chamber;
• and
• a back-flow prevention mechanism including a valve member configured to allow fluid of the back-pressure supply path to flow from each compression chamber to the back-pressure chamber and to prevent fluid of the back-pressure supply path from returning from the back-pressure chamber to each compression chamber.