Actuator for controlling intake pressure in sequential turbo-system
AssigneesToyota Jidosha Kabushiki Kaisha, Aisen Industry Co., Ltd.
InventorsShinobu Ishiyama, Teruo Kumai, Kazuyoshi Ishisaka, Toshiyuki Maehara, Makoto Fujimori, Kimio Nemoto
Life of this patent
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Abstract
In a sequential turbocharger system having a first stage large volume turbo-charger and a second stage small volume turbocharger, a diaphragm actuator is provided for an exhaust bypass valve bypassing a turbine of the small volume turbocharger. The diaphragm actuator has a two step characteristic in relation to an opening of the exhaust bypass valve, so that an increased speed of opening of the exhaust bypass valve is obtained when the pressure downstream of the compressor of the first turbocharger is equal to the pressure downstream of the compressor of the second turbocharger.
Claims25
An internal combustion engine comprising:
- (a) an engine body;
- (b) an intake system connected to the engine body for an introduction of a combustible mixture of gas thereto;
- (c) an exhaust system connected to the engine body for a removal of combustion gas therefrom;
- (d) a first stage large volume turbocharger having a turbine wheel arranged in the exhaust system and driven by a flow of exhaust gas and a compressor arranged in the intake system and mechanically connected to the turbine to pressurize the intake air;
- (e) a second stage small volume turbocharger having a turbine arranged in the exhaust system upstream of the turbine wheel of the first stage large volume turbocharger in the direction of the flow of exhaust gas, and driven by the flow of exhaust gas, and a compressor arranged in the intake system downstream of the compressor of the first stage large volume turbocharger in the direction of the flow of intake air to further pressurize the intake air;
- (f) an exhaust bypass passageway connected to the exhaust system and bypassing the turbine of the second stage small volume turbocharger;
- (g) an exhaust bypass control valve arranged in said exhaust bypass passageway for controlling an amount of exhaust gas bypassing the second stage small volume turbocharger;
- and
- (h) bypass control means, responsive to the intake pressure downstream from each compressor of the first and second stage turbochargers, for controlling the exhaust bypass control valve in such a manner that the bypass control valve opens at a first rate as a function of increasing engine speed after said pressure downstream from the compressor of the second stage turbocharger reaches a predetermined value, and opens at a second rate, greater than the first rate, after the intake pressure downstream from the compressor of the first stage turbocharger reaches said predetermined value.
A valve assembly adapted for controlling a bypass valve in a bypass passageway bypassing a turbine of a small volume turbocharger located nearer an engine than a large volume turbocharger in a sequential turbocharger system, said valve assembly comprising a valve member arranged in the bypass passageway;
- a connecting member connected to the valve member;
- a flexible member arranged to move the connecting member in at least one direction;
- a spring urging the flexible member in a direction to allow the bypass control valve member to close;
- a control chamber on one side of the flexible member, the control chamber being connected to the intake system downstream of the second stage turbocharger so that the valve member starts to open when the pressure level in the control chamber is higher than a predetermined level;
- means for defining a second chamber;
- and means for introducing a control pressure into the second control chamber for generating an additional force to be transmitted to the connecting member to increase the rate of opening movement of the valve member.
Dependencies are inferred from the claim text.