Multistage Compressor

Abstract

A multistage compressor including: at least a first compressor main body and a second compressor main body configured to suck compressed gas discharged from the first compressor main body to discharge the compressed gas with higher pressure; a first driving source configured to drive the first compressor main body; a second driving source configured to drive the second compressor main body; an intermediate pipe configured to connect a discharge side of the first compressor main body and a suction side of the second compressor main body; a low-pressure side discharge piping system branched from the intermediate pipe; an on-off valve disposed in the low-pressure side discharge piping system and configured to switch permission and prohibition of a flow of compressed gas discharged from the first compressor main body; and a control unit configured to control driving of the first driving source and the second driving source.

1 . A multistage compressor comprising:
 at least a first compressor main body and a second compressor main body configured to suck compressed gas discharged from the first compressor main body to discharge the compressed gas with higher pressure;   a first driving source configured to drive the first compressor main body;   a second driving source configured to drive the second compressor main body;   an intermediate pipe configured to connect a discharge side of the first compressor main body and a suction side of the second compressor main body;   a low-pressure side discharge piping system branched from the intermediate pipe;   an on-off valve disposed in the low-pressure side discharge piping system and configured to switch permission and prohibition of a flow of compressed gas discharged from the first compressor main body; and   a control unit configured to control driving of the first driving source and the second driving source,   wherein the control unit is configured to drive the first driving source alone when the on-off valve is opened.   
     
     
         2 . The multistage compressor according to  claim 1 ,
 wherein the intermediate pipe includes a suction side on-off valve configured to switch permission and prohibition of the flow of compressed gas discharged from the first compressor main body to the suction side of the second compressor main body and,   the control unit is configured to drive the first driving source alone when the on-off valve is opened, and the suction side on-off valve is closed.   
     
     
         3 . The multistage compressor according to  claim 1 ,
 wherein the control unit is configured to further drive the second driving source, when the on-off valve is opened.   
     
     
         4 . The multistage compressor according to  claim 1 , comprising:
 a by-pass pipe configured to connect a discharge pipe of the second compressor main body and a downstream side of the on-off valve disposed at the low-pressure side discharge pipe, and   a by-pass valve configured to switch permission and prohibition of a flow of compressed gas into the by-pass pipe, the compressed gas flowing through the discharge pipe,   wherein the control unit is configured to drive the first driving source alone when the by-pass valve is opened, and the suction side on-off valve is closed.   
     
     
         5 . The multistage compressor according to  claim 1 ,
 wherein at least one of the on-off valve, the suction side on-off valve, and the by-pass valve is an electromagnetic valve, and the control unit is configured to control the electromagnetic valve.   
     
     
         6 . A multistage compressor comprising:
 at least a first compressor main body and a second compressor main body configured to suck compressed gas discharged from the first compressor main body to discharge the compressed gas with higher pressure;   a first driving source configured to drive the first compressor main body;   a second driving source configured to drive the second compressor main body;   an intermediate pipe which connects a discharge side of the first compressor main body, and a suction side of the second compressor main body;   a low-pressure side discharge piping system branched from the intermediate pipe;   an on-off valve disposed in the low-pressure side discharge piping system and configured to switch permission and prohibition of a flow of compressed gas discharged from the first compressor main body;   a by-pass pipe configured to connect a discharge pipe of the second compressor main body and a downstream side of the on-off valve of the low-pressure side discharge pipe;   a by-pass valve configured to switch permission and prohibition of a flow of compressed gas into the by-pass pipe, the compressed gas flowing through the discharge pipe;   a suction pipe connected to the intermediate pipe or a suction side of the second compression main body and in which gas flows without passing through the first compressor main body;   a valve body disposed at the suction pipe, and configured to permit or prohibit a flow of the gas; and   a control unit configured to control driving of the first driving source and the second driving source,   wherein the control unit configured to drive the second driving source alone when the on-off valve, the by-pass valve, and the valve body are opened.   
     
     
         7 . The multistage compressor according to  claim 6 ,
 wherein the control unit is configured to drive the first driving source alone in place of the second driving source when the valve body is closed and the on-off valve and the by-pass valve are opened.   
     
     
         8 . The multistage compressor according to  claim 6 ,
 where in the control unit is configured to drive the first driving source also when the by-pass valve and the valve body is closed, and the on-off valve is opened.   
     
     
         9 . The multistage compressor according to  claim 6 ,
 wherein at least one of the on-off valve, the by-pass valve, and the valve body is an electromagnetic valve, and the control unit is configured to control the electromagnetic valve.   
     
     
         10 . The multistage compressor according to  claim 2 ,
 wherein at least one of the on-off valve, the suction side on-off valve, and the by-pass valve is an electromagnetic valve, and the control unit is configured to control the electromagnetic valve.   
     
     
         11 . The multistage compressor according to  claim 3 ,
 wherein at least one of the on-off valve, the suction side on-off valve, and the by-pass valve is an electromagnetic valve, and the control unit is configured to control the electromagnetic valve.   
     
     
         12 . The multistage compressor according to  claim 4 ,
 wherein at least one of the on-off valve, the suction side on-off valve, and the by-pass valve is an electromagnetic valve, and the control unit is configured to control the electromagnetic valve.   
     
     
         13 . The multistage compressor according to  claim 7 ,
 wherein at least one of the on-off valve, the by-pass valve, and the valve body is an electromagnetic valve, and the control unit is configured to control the electromagnetic valve.   
     
     
         14 . The multistage compressor according to  claim 8 ,
 wherein at least one of the on-off valve, the by-pass valve, and the valve body is an electromagnetic valve, and the control unit is configured to control the electromagnetic valve.