The Concept of 2-cylinder Inline Engine

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The Z process can be achieved by several construction types. This is an example of 2-cylinder inline engine. The integrated cylinder head is similar with the original Z engine. The scavenging air pressure is produced by an external 2-stage compressor. The first stage can be, for example, a turbo charger or Lysholm-type screw compressor. The second stage compressor can be integrated into the block (see the pictures below). The compressor connecting rod is connected to the lower end of the main cylinder connecting rod instead of the crankshaft. The track of the joint that connects the rods is elliptical. Therefore, the compressors piston side force is lower. Because the affecting forces in the compressor are much lower than in the main cylinder, the construction can be lighter. This kind of construction has been used since Clerks two stroke engine (1881).

Pictures of the 2-cylinder inline design:

  • 2-d picture of the 2-cylinder design: The block, the valve train, the crankshaft and the compressor cylinder. This is a dual camshaft version. Because the camshafts and the crankshaft have same speed, the camshafts can work as first order balancing shafts. The second order balancing shafts are placed below the crankshaft. This engine is designed to produce approximately 100 kW. The picture has been updated 10.11.2004. Get the picture in pdf-format here (111 kB).

Some rendered 3-d pictures of the 2-cylinder inline design. Click the images for larger view:

Click for larger view Overall view with a turbo. Get higher quality picture here (232 kB).
Click for larger view The camshafts work also as balancing shafts for the first order moment. Get higher quality picture here (358 kB).
Click for larger view The crankshaft and the oil pump shaft form the first order balancer for the compressor cylinder. Get higher quality picture here (311 kB).
Click for larger view The second order balancing shaft is placed under the crankshaft. Get higher quality picture here (325 kB).
Click for larger view The exhaust manifold is on the same side of the engine as the compressor cylinder. Get higher quality picture here (352 kB).
Click for larger view The crankcase and the valve train of the engine. The compressor cylinder is directly attached to the main bearing support.Get higher quality picture here (258 kB).

The poppet type valves can be utilized in the piston compressor to achieve larger flow cross section area compared to common compressor valves. The cam driven poppet valves make possible better durability and higher engine speed. There is some rendered 3-d pictures of the this kind of design below. Click the images for larger view:

Click for larger view Overall view with a turbo. Get higher quality picture here (251 kB).
Click for larger view Get higher quality picture here (370 kB).
Click for larger view The compressor camshaft is driven by the belt. The belt tensioner isn’t drawn in the picture. Get higher quality picture here (315 kB).
Click for larger view Get higher quality picture here (332 kB).
Click for larger view Get higher quality picture here (377 kB).
Click for larger view Get higher quality picture here (283 kB).
Click for larger view The cylinder head of the compressor cylinder. Get higher quality picture here (291 kB).

Some 3-d pictures of the 2-cylinder inline design. Click the images for larger view:

Click for larger view Overall transparent view. The compressor cylinder is directly attached to the main bearing support.
Click for larger view Overall transparent view. The compressor cylinder is foremost in the picture.
Click for larger view The crankcase and the valve train of the engine. The camshafts work also as balancing shafts for the first order moment.
Click for larger view Overall view.
Click for larger view Overall transparent view.
Click for larger view Overall view with turbo.