Abstract: An exhaust gas purification device is capable of reducing the amount of NOx emissions generated at the time of cold start. An exhaust gas purification device includes a urea injection valve, a metal honeycomb, a temperature sensor, and an SCR catalyst in an exhaust passage. It is possible for an exhaust gas temperature of exhaust gas passing through the metal honeycomb to be increased by the metal honeycomb that is capable of being electrically heated by control executed by a control unit ECU. The exhaust gas temperature is detected by the temperature sensor. Based on a temperature-versus-ammonia adsorption amount profile stored in advance in a storage unit of the control unit ECU, ammonia is pre-adsorbed onto the metal honeycomb and the SCR catalyst, and the metal honeycomb is electrically heated at the time of cold start after the temperature detected by the temperature sensor becomes lower than 150° C.

Abstract: An apparatus for detecting magnetism includes a self-exciting fluxgate type magnetic oscillation sensor in each of three axes perpendicular to one another, the magnetic oscillation sensor including a magnetism sensor including a core-coil including a core made of a magnetic material and a coil wound around the core, and an operational amplifier circuit causing an AC excitation current to run through the coil to generate an output in accordance with a strength of an external magnetic field applied to the core. An air core coil not wound around a core is arranged in the vicinity of and in parallel with the core-coil of each of the magnetic oscillation sensors arranged in each of the axes.