Exhaust system

Abstract

To attain an exhaust brake force of an appropriate size while appropriately protecting a super charger.SOLUTION: An exhaust system of a vehicle 1 includes a super charger 30, an exhaust gas treatment device 55 and a control device 200. The super charger 30 includes a turbine 36 having a variable nozzle mechanism 40. The control device 200 executes calculation processing for calculating a correction amount relative to a reference opening as a reference of an opening of the variable nozzle mechanism 40, and nozzle control for controlling an opening according to a reference opening and a correction amount for operating an exhaust brake of the vehicle 1. A temperature of exhaust gas in an exhaust manifold 50 or a temperature of the turbine 36 is a temperature T4, and a temperature of the exhaust gas treatment device 55 is temperature TE. The calculation processing is executed according to the temperature T4 and the temperature TE by using a relation between the temperature T4 and the temperature TE, and a correction amount, previously set so that a ratio of pressure P4 in the exhaust manifold 50 to pressure P6 in an exhaust pipe 54 is equal to or less than a restraint value.SELECTED DRAWING: Figure 1

Claims

1. An exhaust system for exhaust braking of a vehicle equipped with an engine, A supercharger including a turbine with a variable nozzle mechanism, An exhaust gas treatment device is provided downstream of the turbine in the direction in which the exhaust gas of the engine flows, and which processes the exhaust gas. A first exhaust pipe connected between the engine and the turbine, A second exhaust pipe connected between the turbine and the exhaust gas treatment device, The control device includes a calculation process that calculates a correction amount for a reference opening degree, which is the basis for the opening degree of the variable nozzle mechanism, and a nozzle control that controls the opening degree according to the reference opening degree and the correction amount in order to activate the exhaust brake. If the temperature of the exhaust gas in the first exhaust pipe or the temperature of the turbine is defined as the first temperature, and the temperature of the exhaust gas treatment device is defined as the second temperature, The calculation process is performed according to the first and second temperatures, using a predetermined relationship between the first and second temperatures and the correction amount, such that the ratio of the first pressure (pressure in the first exhaust pipe) to the second pressure (pressure in the second exhaust pipe) is less than or equal to a constraint value, in an exhaust system.

2. If the first pressure at which the deceleration of the vehicle reaches its target value is defined as the target deceleration pressure, and the ratio at which the first pressure is the target deceleration pressure is defined as the target deceleration ratio value, then the target deceleration ratio value is lower than the constraint value. The exhaust system according to claim 1, wherein the relationship is predetermined such that the ratio is less than or equal to the constraint value and greater than or equal to the target deceleration ratio value.

3. The exhaust system according to claim 1, wherein the correction amount is smaller when the second temperature is high than when the second temperature is low.

4. The exhaust gas treatment device includes a catalyst member for modifying the exhaust gas. The exhaust system according to any one of claims 1 to 3, wherein the second temperature is the temperature of the catalyst member.

5. The exhaust gas treatment device includes a plurality of catalyst members, each of which modifies the exhaust gas. The exhaust system according to any one of claims 1 to 3, wherein the second temperature is the temperature of the upstream catalytic converter among the plurality of catalytic converters in the path through which the exhaust gas flows.

6. The exhaust system according to any one of claims 1 to 3, wherein the reference opening is set according to the engine speed, the ambient temperature around the vehicle, and the atmospheric pressure around the vehicle.

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