Patent ID: 7722801

Claim:
A vacuum carburizing apparatus which introduces a carburizing gas into a carburizing chamber to subject an article to vacuum carburizing, comprising: a carburizing chamber that houses the article therein, a vacuum pump that exhausts gas from the carburizing chamber to obtain vacuum, a carburizing gas supply unit that supplies carburizing gas into the carburizing chamber in pulse mode, a reflux pipe which connects an intake side of the vacuum pump and an exhaust side of the vacuum pump, an opening and closing valve which is located in the reflux pipe, and a control unit which opens the opening and closing valve when a supply of the carburizing gas into the carburizing chamber is started and closes the opening and closing valve when the supply ends, and a flow amount adjusting valve which is located in the reflux pipe, the flow amount adjusting valve adjusting an amount of carburizing gas flowing back to the intake side of the vacuum pump.