Engine braking method and system
AssigneeCummins Turbo Technologies Limited
InventorPierre French
Life of this patent
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Abstract
During engine braking of a turbocharged internal combustion engine, the exhaust gas pressure increases and this is used to pressurize the seals between the turbocharger shaft and the bearing housing so as to prevent oil leakage into the compressor housing. Immediately after engine braking, stored exhaust gas pressure is used to pressurize the seals at the turbine end so as to prevent oil leakage into the turbine housing. In an alternative arrangement the exhaust gas is used to generate a reduced pressure in the bearing housing to increase the pressure gradient across the seals.
Claims28
An engine braking method for an internal combustion engine having an air intake path and an exhaust gas path, a turbocharger comprising a turbine in the exhaust gas path and a compressor in the intake path, the turbine comprising a turbine wheel rotatably disposed in a turbine housing, the compressor comprising a compressor impeller rotatably disposed in a compressor housing, the turbine wheel and compressor impeller being connected by a turbocharger shaft, a bearing housing disposed between the compressor and turbine for housing a bearing assembly to support the turbocharger shaft in rotation, at least one first seal between a compressor end of the shaft and the bearing housing, the method comprising:
- operating the engine in an engine braking mode by activating an exhaust gas brake to impede the flow of exhaust gas in the exhaust gas path when the engine throttle is closed, thereby generating an exhaust gas back-pressure in the exhaust gas path;
- diverting at least a portion of the exhaust gas during engine braking mode from the exhaust gas path in order to increase the pressure gradient across the at least one first seal in the direction from the bearing housing to the compressor housing.
An engine braking system comprising:
- an internal combustion engine with an air intake path and an exhaust gas path;
- a turbocharger comprising a compressor for delivering pressurised air to the air intake path and a turbine for receipt of the exhaust gas from the engine, the turbine comprising a turbine wheel rotatably disposed in a turbine housing, the compressor comprising a compressor impeller rotatably disposed in a compressor housing, the turbine wheel and compressor impeller being connected by a turbocharger shaft, a bearing housing disposed between the compressor and turbine for housing a bearing assembly to support the turbocharger shaft in rotation, at least one first seal between the shaft and a compressor end of the bearing housing;
- an exhaust gas brake in the exhaust gas path and operable to effect engine braking, an exhaust gas bleed path extending from the exhaust gas path to a location between the at least one first seal and the compressor housing for diverting at least a portion of the exhaust gas from the exhaust gas path during engine braking.
A method for reducing oil leakage in a turbocharger comprising a compressor for delivering pressurised air to an air intake path of an internal combustion engine, and a turbine for receipt of the exhaust gas from the engine, the turbine comprising a turbine wheel rotatably disposed in a turbine housing, the compressor comprising a compressor impeller rotatably disposed in a compressor housing, the turbine wheel and compressor impeller being connected by a turbocharger shaft, a bearing housing disposed between the compressor and turbine for housing a bearing assembly to support the turbocharger shaft in rotation, at least one first seal between a compressor end of the shaft and the bearing housing, activating an exhaust gas brake to impede the flow of exhaust gas into the turbine and diverting at least a portion of the impeded exhaust gas flow in order to increase the pressure gradient across the at least one first seal in the direction from the bearing housing to the compressor housing.
Dependencies are inferred from the claim text.