| 摘要 |
PURPOSE:To control oil supply into a proper amount throughout the range of rotor revolutions of a vacuum pump by furnishing a flow control valve between an oil supply hole formed in the housing and an oil pump to press forward the lubricating oil into the housing. CONSTITUTION:The relationship between the number of revolutions of a rotor and the oil amount is stored in a control device 48 previously. Signals from a neg. pressure sensor 50, temp. sensor 52 and revolutional signal takeout terminal 54 are fed in to provide grasp of the operational condition of vacuum pump 10. A flow control valve 46 is duty controlled at a frequency around 5Hz by a pulsed signal from the abovementioned control device 48 to perform opening/ closing of an oil supply hole 42. That is, the control device 48 sets the duty greater to increase the time of opening of the flow control valve 46, in case the engine operates at a low revolving speed and, at the same time, the neg. pressure chamber 60 of the vacuum pump 10 has a low pressure. Thus the amount of oil supply to the vacuum chamber 60 is increased to cause enhancement of the air-tightness of the vacuum pump.
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