Air supply system with reduced oil passing in compressor

Abstract

An air supply system includes a compressor having a compression chamber, an inlet port through which air flows into the compression chamber and an outlet port through which air exits the compression chamber, an unloader which causes the compressor to be in an unloaded state when a desired system air pressure is maintained, an isolation valve preventing inlet air from flowing into the inlet port of the compressor when the compressor is in the unloaded state, and a source of pressurized air supplying pressurized air to the inlet port of the compressor at least when the isolation valve prevents inlet air from flowing into the inlet port of the compressor.

1 . An air supply system comprising:
 a compressor having a compression chamber, an inlet port through which air flows into the compression chamber and an outlet port through which air exits the compression chamber;   an unloader which causes said compressor to be in an unloaded state in response to a pneumatic signal received at a signal port;   an isolation valve having an inlet port, an outlet port and a signal port, the inlet port of said isolation valve being in fluid communication with a source of inlet air, and the outlet port of said isolation valve being in fluid communication with the inlet port of said compressor, said isolation valve allowing air to flow from the inlet port of said isolation valve to the outlet port of said isolation valve, and thereby allowing air to flow from the source of inlet air to the inlet port of said compressor, when no pneumatic signal is received at the signal port of the isolation valve, and preventing air from flowing from the inlet port of said isolation valve to the outlet port of said isolation valve, and thereby preventing air from flowing from the source of inlet air to the inlet port of said compressor, when a pneumatic signal is received at the signal port of the isolation valve;   a governor having an unloading port in fluid communication with the signal port of said isolation valve and with the signal port of said unloader, said governor supplying a pneumatic signal to the signal port of said isolation valve and the signal port of said unloader when a desired system air pressure is maintained; and   a source of pressurized air supplying pressurized air to the inlet port of said compressor at least when the pneumatic signal is received by said isolation valve.   
   
   
       2 . The air supply system of  claim 1  wherein the pressurized air supplied by said source of pressurized air to the inlet port of said compressor has a pressure about equal to a pressure of air in a crankcase of said compressor. 
   
   
       3 . The air supply system of  claim 1  wherein said source of pressurized air comprises an air reservoir in fluid communication with the inlet port of said compressor. 
   
   
       4 . The air supply system of  claim 3  further comprising a pressure regulator in fluid communication between the air reservoir and the inlet port of said compressor, said pressure regulator regulating a pressure of air supplied by the reservoir such that the pressurized air supplied by the reservoir to the inlet port of said compressor has a pressure about equal to a pressure of air in a crankcase of said compressor. 
   
   
       5 . The air supply system of  claim 1  wherein the unloading port of said governor is in fluid communication with the inlet port of said compressor, such that said source of pressurized air comprises the unloading port of said governor. 
   
   
       6 . The air supply system of  claim 5  further comprising a pressure regulator in fluid communication between the unloading port of said governor and the inlet port of said compressor, said pressure regulator regulating a pressure of air supplied by the unloading port of said governor such that the pressurized air supplied by the unloading port of said governor to the inlet port of said compressor has a pressure about equal to a pressure of air in a crankcase of said compressor. 
   
   
       7 . The air supply system of  claim 5  wherein said governor further comprises a reservoir port, and wherein the air supply system further comprises a reservoir having a port in fluid communication with the reservoir port of said governor. 
   
   
       8 . The air supply system of  claim 1  wherein said isolation valve comprises a valve body moveable, in response to the pneumatic signal received at the signal port of the isolation valve, between an open position in which said isolation valve allows air to flow from the inlet port of said isolation valve to the outlet port of said isolation valve, and thereby allows air to flow from the source of inlet air to the inlet port of said compressor, and a closed position in which said isolation valve prevents air from flowing from the inlet port of said isolation valve to the outlet port of said isolation valve, and thereby prevents air from flowing from the source of inlet air to the inlet port of said compressor. 
   
   
       9 . The air supply system of  claim 8  wherein the valve body is biased toward the open position, and is moveable against the bias to the closed position when the pneumatic signal is received at the signal port of the isolation valve. 
   
   
       10 . An air supply system comprising:
 a compressor having a compression chamber, an inlet port through which air flows into the compression chamber and an outlet port through which air exits the compression chamber;   an unloader which causes said compressor to be in an unloaded state when a desired system air pressure is maintained;   an isolation valve preventing inlet air from flowing into the inlet port of said compressor when said compressor is in the unloaded state; and   a source of pressurized air supplying pressurized air to the inlet port of said compressor at least when said isolation valve prevents inlet air from flowing into the inlet port of said compressor.   
   
   
       11 . The air supply system of  claim 10  wherein the pressurized air supplied by said source of pressurized air to the inlet port of said compressor has a pressure about equal to a pressure of air in a crankcase of said compressor. 
   
   
       12 . The air supply system of  claim 10  wherein said source of pressurized air comprises an air reservoir in fluid communication with the inlet port of said compressor. 
   
   
       13 . The air supply system of  claim 12  further comprising a pressure regulator in fluid communication between the air reservoir and the inlet port of said compressor, said pressure regulator regulating a pressure of air supplied by the reservoir such that the pressurized air supplied by the reservoir to the inlet port of said compressor has a pressure about equal to a pressure of air in a crankcase of said compressor. 
   
   
       14 . The air supply system of  claim 10  further comprising a governor in fluid communication with said isolation valve and with said unloader, said governor signaling said unloader to cause the compressor to be in the unloaded state when the desired system air pressure is maintained, and signaling said isolation valve to prevent inlet air from flowing into the inlet port of said compressor when the desired system air pressure is maintained. 
   
   
       15 . The air supply system of  claim 14  wherein said governor is in fluid communication with the inlet port of said compressor, such that said source of pressurized air comprises said governor. 
   
   
       16 . The air supply system of  claim 15  further comprising a pressure regulator in fluid communication between said governor and the inlet port of said compressor, said pressure regulator regulating a pressure of air supplied by said governor such that the pressurized air supplied by said governor to the inlet port of said compressor has a pressure about equal to a pressure of air in a crankcase of said compressor. 
   
   
       17 . The air supply system of  claim 15  further comprising a reservoir in fluid communication with said governor. 
   
   
       18 . An air supply system comprising:
 a compressor having a compression chamber, an inlet port through which air flows into the compression chamber and an outlet port through which air exits the compression chamber;   an unloader which causes said compressor to be in an unloaded state in response to a pneumatic signal received at a signal port;   an isolation valve having an inlet port, an outlet port and a signal port, the inlet port of said isolation valve being in fluid communication with a source of inlet air, and the outlet port of said isolation valve being in fluid communication with the inlet port of said compressor, said isolation valve further comprising a valve body moveable between an open position in which said isolation valve allows air to flow from the inlet port of said isolation valve to the outlet port of said isolation valve, and thereby allows air to flow from the source of inlet air to the inlet port of said compressor, and a closed position in which said isolation valve prevents air from flowing from the inlet port of said isolation valve to the outlet port of said isolation valve, and thereby prevents air from flowing from the source of inlet air to the inlet port of said compressor, wherein the valve body is biased toward the open position, and is moveable against the bias to the closed position when a pneumatic signal is received at the signal port of the isolation valve;   a governor having an unloading port in fluid communication with the signal port of said isolation valve and with the signal port of said unloader, said governor supplying a pneumatic signal to the signal port of said isolation valve and the signal port of said unloader when a desired system air pressure is maintained; and   an air reservoir in fluid communication with the inlet port of said compressor, said air reservoir supplying pressurized air to the inlet port of said compressor at least when the pneumatic signal is received by said isolation valve.   
   
   
       19 . The air supply system of  claim 18  further comprising a pressure regulator in fluid communication between the air reservoir and the inlet port of said compressor, said pressure regulator regulating a pressure of air supplied by the reservoir such that the pressurized air supplied by the reservoir to the inlet port of said compressor has a pressure about equal to a pressure of air in a crankcase of said compressor. 
   
   
       20 . An air supply system comprising:
 a compressor having a compression chamber, an inlet port through which air flows into the compression chamber and an outlet port through which air exits the compression chamber;   an unloader which causes said compressor to be in an unloaded state in response to a pneumatic signal received at a signal port;   an isolation valve having an inlet port, an outlet port and a signal port, the inlet port of said isolation valve being in fluid communication with a source of inlet air, and the outlet port of said isolation valve being in fluid communication with the inlet port of said compressor, said isolation valve further comprising a valve body moveable between an open position in which said isolation valve allows air to flow from the inlet port of said isolation valve to the outlet port of said isolation valve, and thereby allows air to flow from the source of inlet air to the inlet port of said compressor, and a closed position in which said isolation valve prevents air from flowing from the inlet port of said isolation valve to the outlet port of said isolation valve, and thereby prevents air from flowing from the source of inlet air to the inlet port of said compressor, wherein the valve body is biased toward the open position, and is moveable against the bias to the closed position when a pneumatic signal is received at the signal port of the isolation valve;   a governor having an unloading port in fluid communication with the signal port of said isolation valve and with the signal port of said unloader, said governor supplying a pneumatic signal to the signal port of said isolation valve and the signal port of said unloader when a desired system air pressure is maintained; and   wherein the unloading port of said governor is in fluid communication with the inlet port of said compressor, such that the unloading port of said governor supplies pressurized air to the inlet port of said compressor at least when the desired system air pressure is maintained.   
   
   
       21 . The air supply system of  claim 20  further comprising a pressure regulator in fluid communication between the unloading port of said governor and the inlet port of said compressor, said pressure regulator regulating a pressure of air supplied by the unloading port of said governor such that the pressurized air supplied by the unloading port of said governor to the inlet port of said compressor has a pressure about equal to a pressure of air in a crankcase of said compressor. 
   
   
       22 . The air supply system of  claim 20  wherein said governor further comprises a reservoir port, and wherein the air supply system further comprises a reservoir having a port in fluid communication with the reservoir port of said governor.