Exhaust Gas Diverter

Abstract

A gas diverter includes at least one port circumscribed by a port seat, and a valve subassembly for selectively obstructing the port. The valve subassembly comprises: (a) an actuation arm; (b) a disk coupled to the arm, and (c) an actuator for selectively causing the disk to be urged against said port seat to obstruct said port. In operation, the disk deforms elastically as it is urged against the port seat.

Description

CROSS-REFERENCE TO RELATED APPLICATION(S)[0001]The present application is related to and claims priority benefits from U.S. Provisional Patent Application Ser. No. 60 / 945,342, entitled “Exhaust Gas Diverter”, filed on Jun. 20, 2007. The present application is also related to and claims priority benefits from U.S. patent application Ser. No. 11 / 676,499, entitled “Combustion Engine Exhaust After-treatment System Incorporating Syngas Generator”, filed on Feb. 19, 2007. The '342 and '499 applications are each hereby incorporated by reference in their entirety.FIELD OF THE INVENTION[0002]The present invention relates to an engine exhaust gas diverter and a method of operating such a diverter. In particular, the invention relates to an exhaust gas diverter, suitable for use in a combustion engine exhaust after-treatment system, which alternately obstructs the exhaust stream from flowing into one of two outlet ports, and a method of actuating the diverter. The engine can be part of a vehic...

AI Technical Summary

Benefits of technology

"The patent describes gas diverters that can be used to direct exhaust gas from an engine to multiple after-treatment devices. The gas diverters have a valve sub-assembly that can selectively obstruct the ports to control the flow of exhaust gas. The valve sub-assembly includes a pivotable arm and two disks that deform elastically as they are urged against the port seat. The gas diverters can be used in engine systems with exhaust after-treatment systems to improve emissions control. The actuator causes the disk to decelerate as it approaches the port seat to obstruct the port, during operation of the valve sub-assembly. The technical effects of the gas diverters include improved emissions control and selective direction of exhaust gas flow for multiple after-treatment devices."

Problems solved by technology

The capacity of the adsorbents to adsorb and store NOx is limited.

Other contaminants in the exhaust stream such as sulfur (S) may also be adsorbed, further contributing to the reduction in capacity.

The primary disadvantage of this configuration is that a substantial amount of reducing agent is required to create sufficiently rich exhaust stream conditions because of the high engine exhaust stream flow rates.

This leads to an undesirably high operating cost.

Some of these challenging operating conditions include the presence of particulates and contaminants in the exhaust stream; a wide operating temperature range, for example, −40° to +500° C.; high temperatures; thermal cycling; thermal gradients; low exhaust stream pressures; vibration; and a corrosive environment.

Degradation of materials as a result of prolonged exposure to such conditions can diminish diverter performance significantly, ultimately leading to diverter failure and in some cases system failure.

Many valve designs are unsuitable for automotive or other mobile applications due to excessive size, prohibitive cost, slow response and the required actuation force.

Each valve design poses specific challenges for the exhaust gas diverter application.

A disadvantage of the butterfly design is the high internal leak rates across the valve due to the clearances required between the valve plate and the internal sealing surfaces that are needed to accommodate thermal expansion.

A disadvantage of the ball design is the size, weight and cost.

A disadvantage of the poppet design is the high pressure drop across the valve, or large valve size required, as the poppet remains in the direct path of the exhaust gas stream acting as a restrictor.

A disadvantage of the gate design is the high internal leak rates due to the clearances required for thermal expansion and actuation.

A disadvantage of conventional flapper designs is also the high internal leak rates.

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