Exhaust gas purification for a hydrogen engine

Abstract

An exhaust gas purification system for a hydrogen engine is provided in which hydrogen gas is supplied in the hydrogen engine as a fuel for combustion, and is also supplied to the exhaust gas after combustion to improve purification of the exhaust element. The exhaust gas purification system includes a hydrogen storage tank, the hydrogen engine, and a catalyst provided in an exhaust pipe, and is capable of supplying hydrogen gas through the exhaust pipe during operation of the hydrogen engine. An upstream-side exhaust gas sensor is provided on the exhaust pipe upstream of the catalyst. An exhaust-side hydrogen gas injection device is provided upstream of the upstream-side exhaust gas sensor. Control means control the amount of hydrogen gas for supply to the hydrogen engine based on the detection by the upstream-side exhaust gas sensor as a feedback control so as to obtain the exhaust gas having a predetermined lean air-fuel ratio, and control the amount of hydrogen gas supplied from the exhaust-side hydrogen gas injection device to be less than that supplied to the hydrogen engine.

1 . An exhaust gas purification system for a hydrogen engine, having
 a hydrogen storage tank for storing hydrogen at high pressure,   a hydrogen engine for combusting hydrogen supplied from the hydrogen storage tank, and   a catalyst provided in an exhaust pipe of the hydrogen engine,   the exhaust gas purification system being capable of supplying hydrogen gas into the exhaust pipe during operation of the hydrogen engine, comprising:   an upstream-side exhaust gas sensor disposed on the exhaust pipe upstream of the catalyst for detecting the exhaust gas composition;   an exhaust-side hydrogen gas injection device disposed upstream of the upstream-side exhaust gas sensor for injecting hydrogen gas into the exhaust pipe; and   control means which control the amount of hydrogen gas for supply to the hydrogen engine based on the detection by the upstream-side exhaust gas sensor as a feedback control so as to obtain an exhaust gas having a predetermined lean air-fuel ratio, and which control the amount of hydrogen gas supplied from the exhaust-side hydrogen gas injection device to be less than that supplied to the hydrogen engine.   
   
   
       2 . The exhaust gas purification system for a hydrogen engine as defined in  claim 1 , wherein a downstream-side exhaust gas sensor for detecting exhaust gas composition is provided in the exhaust pipe downstream from the catalyst,
 the control means monitors a rate of reduction of the exhaust gas after having passed (he catalyst with hydrogen gas supplied from the exhaust-side hydrogen gas injection device, based on the detection by the downstream-side exhaust gas sensor, and perform a feedback control to correct the amount of hydrogen gas supply for increase or decrease thereof.