The Relationship between Rate of Pressure Rise and Connecting-Passage Area in a Swirl Chamber Type Diesel Engine

Abstract

This paper is a sequel to the investigation on effects of connecting passage area of divided chamber type Diesel engine on knock intensity : The rates of pressure rise in the auxiliary-and the main chambers of a swirl chamber type engine were measured from indicator cards under a light load. The test results are summarized as follows : Above 1000 rpm of the engine speed, the rate of pressure rise in the swirl chamber and the amplitude of detonation-like pressure oscillation rapidly augment as the area ratio of the passage is reduced. The relationship between rates in the main chamber and in the swirl chamber can be classified into three stages according to the ratio. In the smallest ratio range the gas flowing out from the swirl chamber is delayed by the connecting passage, thus resulting in a relatively low rate of pressure rise compared with that in the main chamber. In the intermediate area range the rate in the main chamber is nearly equal to that in the swirl chamber. The larger area ratio gives higher rate than in the swirl chamber because of combustion in the main chamber due to easier outflow of unburned fuel.