PURPOSE: To certainly avoid peel-off of a lubricating film which may be caused by high surface pressure between a pump plunger reciprocatingly driven by driving devices and a cylinder bore, by forming a sectional area widening portion opened to a low pressure chamber by means of the cylinder bore at its low pressure side end within an upper range.
CONSTITUTION: A pump plunger 1 which is axially guided inside a cylinder bore 3 formed in a cylinder bush 5 is reciprocatingly driven by a cam driving device. A pump working chamber 9 limited by a pressure valve unit 33 is determined in the cylinder bore 3. At least one control cutout 11 communicated with the pump working chamber 9 is formed on an outer perpheral surface of the pump plunger 1. A sectional area widening portion 61 opened to a low pressure chamber 23 is formed in the cylinder bore 3, at its end of low pressure side within an upper range 25. The diamter of the portion 61 is greater than that of the cylinder bore 3 by 20 micrometers at maximum.
YURUGEN KIRUSHIYUNAA
ZANDORO ZOTSUKORU
BUORUFUGANGU ETSUKERU
