Low-backpressure compressor

The invention discloses a low-backpressure compressor, comprising a shell body and a compression mechanism, wherein the compression mechanism is provided with two exhaust cavities including a first exhaust cavity and a second exhaust cavity, the second exhaust cavity is communicated with the first exhaust cavity; the compression mechanism comprises an air cylinder assembly and two bearings, the air cylinder assembly comprises at least one air cylinder, and a slip sheet cavity is arranged in each air cylinder. The two bearings are respectively a master bearing and a secondary bearing, an exhaust clapboard is arranged between at least one bearing and the air cylinder assembly, and at least one of the first exhaust cavity and the second exhaust cavity is limited by the exhaust clapboard and the corresponding bearing. According to the low-backpressure compressor, the exhaust cavities and the exhaust clapboard structure can be simplified, the sealing surfaces of the exhaust cavities are simple planes and are mechanically sealed, the cost is low and the reliability is high; the problems that low-backpressure compressor component structure is excessively complex, the technique difficulty is large, and the production cost is high are solved, and the reliability of the compressor is improved.