Basic Engine: Overview Saab 9-5 I рестайлинг 2

Description

The valve gear incorporates hydraulic tappets which keep the valve clearance within a limited working range of 2.05 mm (0.081 in), which is between 18.75 and 20.8 mm (0.738-0.819 in) from the cam to the valve. Each tappet has two storage chambers and one high-pressure chamber, which is sealed against one of the storage chambers by means of a spring-loaded ball valve. A return spring in the high-pressure chamber acts on the sliding plunger so that any clearance between the tappet and the base circle of the cam is eliminated. At the same time, the highpressure chamber expands and makes up the oil volume to compensate for leakage losses in the gap between the plunger and cylinder which occur at actuating pressure. Under some conditions the hydraulic tappets may give rise to a chattering noise of varying intensity. In most cases this noise will be short-lived and no remedial action will be necessary. Details are given in the following of the most common types of noise, the most probable cause of the noise and preliminary action which may be taken to eliminate the noise.

The hydraulic mounting has two chambers containing a special damping fluid. Interposed between the two chambers are a diaphragm and a passage, the length and cross-sectional area of which determine the dampening characteristics of the mounting. The diaphragm absorbs the forces generated by normal small movements of the engine. If engine movement is more pronounced, the damping action of the diaphragm will be insufficient. Fluid is then forced from the upper into the lower chamber, equalizing the pressure. This gives the hydraulic mounting a progressive damping action in that the resistance of the mounting increases with increased load.

Scheme 1

ENGINE DATA SPECIFICATION