| 摘要 |
<p>The method involves producing (F) an average value from total opening times of adjusting valves, and determining (G) a preheating temperature threshold value of a heating curve from a medium external temperature. The threshold value is increased when a percentage ratio of the average value to detection time is greater than or equal to an upper limit that amounts to 55 percentages. The threshold value is reduced when the ratio is smaller than or equal to a lower limit that amounts to 45 percentages, and the threshold value is maintained when the ratio lies in an area between the limits.</p> |
