Interstage gas injection for multi-stage turbocharged natural gas engine

An internal combustion engine system, comprising:

• an internal combustion engine including at least one intake system for delivering a charge flow to at least a portion of a plurality of cylinders of the internal combustion engine and at least one exhaust system for receiving exhaust gas from at least a portion of the plurality of cylinders;
• at least one high-pressure turbocharger with a first high pressure turbine in the exhaust system and at least one low pressure turbocharger with a first low pressure turbine in the exhaust system downstream of the first high pressure turbine;
• the low pressure turbocharger further including a first low pressure compressor operably connected to the low pressure turbine with the low pressure compressor connected in the intake system to receive and compress intake air, and the high pressure turbocharger further including a first high pressure compressor operably connected with the first high pressure turbine with the first high pressure compressor connected in the intake system downstream of the low pressure compressor;
• a fuel injector connected to the intake system between the low pressure compressor and the high pressure compressor to provide a fuel to the intake air and form the charge flow for compression by the high pressure compressor;
• and
• a multi-stage bypass configured to selectively bypass at least a portion of the charge flow in the intake system from a first location that is downstream of the high pressure compressor to a second location that is upstream of the low pressure compressor.

An internal combustion engine system, comprising:

• an internal combustion engine including at least one intake system for delivering a charge flow to at least a portion of a plurality of cylinders of the internal combustion engine and at least one exhaust system for receiving exhaust gas from at least a portion of the plurality of cylinders;
• a first high pressure turbocharger with a first high pressure turbine in a first exhaust passage of the exhaust system and a second high pressure turbocharger with a second high pressure turbine in a second exhaust passage of the exhaust system;
• a first low pressure turbocharger with a first low pressure turbine connected to the first exhaust passage and a second low pressure turbocharger with a second low pressure turbine connected to the second exhaust passage;
• the first low pressure turbocharger further including a first low pressure compressor connected to a first intake passage portion and the second low pressure turbocharger further including a second low pressure compressor connected to a second intake passage portion of the intake system, wherein outlets of the first and second low pressure compressors are connected to a first common intake passage portion to provide compressed intake air thereto;
• a fuel injector connected to the first common intake passage portion that is configured to provide a fuel to the intake air to form the charge flow, wherein the first common intake passage branches to third and fourth intake passage portions downstream of the connection of the fuel injector;
• and
• the first high pressure turbocharger further including a first high pressure compressor connected to the third intake passage portion and operably connected to the first high pressure turbine and the second high pressure turbocharger including a second high pressure compressor connected to the fourth intake passage portion and operably connected to the second high pressure turbine, the first and second high pressure compressors each being operable to compress the charge flow received from the respective third and fourth intake passage portions.