| 摘要 |
A pushrod-operated-valve-in-head six cylinder engine has two intake valves per cylinder. Five of the seven air intake runners in the cylinder head are arranged so that at least one intake valve port of each cylinder adjacent to another cylinder shares an intake runner with an intake valve port of the adjacent cylinder. Each of the shared runners feeds one valve port of each of two adjacent cylinders. The firing order of the engine is such that intake strokes for the adjacent cylinders are separated in time. Therefore, only one of the sharing cylinders at a time is supplied with air by the shared runner. In addition, because each runner is supplying only one valve per cylinder, there are two runners feeding each cylinder. For each cylinder, one port is the tangential type, and the other is the helical type. In one embodiment, the valve port connections to the shared runners are arranged for variable swirl production, by pairing the same style intake ports on each runner e.g. two tangential ports or two helical ports, so air flow can be shut off from the tangential ports at low speed to increase swirl. The tangential ports direct flow into the cylinder tangentially to the cylinder wall and are located 270 degrees around the cylinder in an upstream direction from the helical ports to minimize interference of the tangential flow with the swirl produced by the helical ports.
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