| 摘要 |
PURPOSE:To preheat the working oil in a short time by a method in which a pipe confined with a medium, e.g., water, etc., is passed through the inside of a working oil tank and a prime mover and the heat of the prime mover is transmitted through the medium to the working oil. CONSTITUTION:A close-circuited pipe 6 confined with a medium, e.g., water, etc., a water supply pump 7, the first heat exchanger 8 to exchange the heat of an engine 5 with water, and the second heat exchanger 9 to exchange the heat of hot water heated with the working oil are provided. When a three-way valve 11 is switched in such a way as to connect the outlet of the heat exchanger 8 with the inlet of the heat exchanger 9 and the engine 5 is actuated, the water supply pump 7 is operated to circulate water in the pipe 6. Then, the water in the pipe 6 is heated by the heat of the engine 5 to hot water in the heat exchanger 8, and when the hot water passes through the heat exchanger 9, heat exchange takes place between the hot water and the working oil in the working oil tank 4. |
