Secondary air control device
AssigneeHitachi, Ltd.
InventorsTakeshi Atago, Yukio Hosho, Shoji Shimo
Life of this patent
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Abstract
A secondary air control device which comprises an air passage communicating an air pump with a recombustion device and having a resistor such as an orifice provided midway of the passage and a control valve for maintaining substantially constant the pressure ratio of the pressure on the upstream side of the aforesaid resistor to that on the downstream side thereof, said control valve being so designed as to be operated in association with the pressure of the secondary air and that of exhaust gas, thereby eliminating fluctuation in pressure in the secondary air due to reduction in the discharging performance of the air pump, and thus the secondary air proportional in quantity to the exhaust gas from an engine may be supplied.
Claims7
In a secondary air control device in which secondary air from an air pump is supplied through an air passage to an exhaust gas purifying re-combustion device to burn combustible components contained in the exhaust gas from an engine within the re-combustion device, the improvement comprising an orifice mounted in the air passage, and control valve means operatively associated with the air passage communicating the air pump with the orifice for varying pressure on the upstream side of the orifice in response to pressure in the re-combustion device and maintaining a substantially constant ratio of the pressure on the upstream side of the orifice to the pressure in the re-combustion device.
Dependencies are inferred from the claim text.