crankshaft of TWO STROKE INTERNAL combustion engine

Autor: Ol`khovikov Viktor Vladislavovich

Contact: rosting@comp-net.ru

1.      (57) This patent can be used in production of internal-combustion engines. The crankshaft comprises two semi-axis with crank webs connected by a pin pressed in a con-rod. In the crank webs there are slots, in which the above pin moves. The slots are located along a curve close to the unclosed ellipse line. The proposed crankshaft design allows for increasing of the engine power and decreasing of the fuel consumption.

2.      The patent relates to automobile-tractor machinery construction and can be used in production of two stroke engines for motorcycles, mopeds and motor boats.

The known designs of crankshafts of two stroke internal combustion engines are used in motorcycles, mopeds and motor boats. The example is a built-up crankshaft of two stroke engine known from the patent of France 2663088 data are as of 13.12.91, cl. F 16 C 3/10. It contains semi-axis with crank webs connected by a pin.

This crankshaft design has a rigid connection of the crankshaft with a con-rod. The piston amplitude is along the sinusoid that does not completely comply with the thermodynamics of gas pressure on the piston. At the maximum gas pressure, the reach of arm of the crankshaft rotation made by the con-rod is minimal that decreases greatly the engine efficiency.

The aim of our patent is to increase the power and efficiency of the engine.

The posed aim is reached by the following: the crankshaft of the two stroke internal combustion engine contains semi-axis with crank webs made in the form of cog-wheels and fitted with slots that interact with a pin floating in them. The pin is pressed in a con-rod. The slots are located along a curve close to the unclosed ellipse, of which shorter axis is directed radially to the crankshaft rotation axis.

The con-rod pin floating in the slots will allow for the significant increase of the arm of the crankshaft rotation made by the con-rod from the moment of the piston location in the dead point, when the gas pressure on the piston is minimal. This design and the interaction of the gas pressure dynamics with the arm of the crankshaft rotation will increase significantly the power and efficiency of the engine.

Fig.1 presents the design of the crankshaft interacting with the con-rod, pin and piston.

Fig.2 presents the principal kinematic scheme of the crankshaft and piston operation within one time step (rotation) of the crankshaft with breaking into 0, 10, 90, 180, 230 270 and 316° (positions a, b, c, d, e, f and g, respectively).

The crankshaft design contains semi-axis 1, crank webs 2, pin 3, shaft 4 that prevents the displacement of crank webs relative to each other.  

3.      The crank webs are in the form of cog wheels with cogs 5 over the crank web perimeter and slots 6 located along the curve close to the unclosed ellipse.

Figures 1 and 2 present the con-rod 7, pin 8 of the piston 9 and cylinder10.  

The crankshaft of the two stroke  internal combustion engine operates in the following way: gas pressure pushes the piston 9 downward. The piston transmits the pressure to the slot 6 through the pin 8, con-rod 7 and pin 3 rotating the crankshaft. The rotational moment on the power take-off gear-shaft 4 is transmitted by a gearing 5 located on the crank webs 2. Fig 2 presents the principal kinematic scheme of the engine operation within one rotation of the crankshaft. At the upper dead point (fig. 2a) the cycle of the operating mixture compression is completed. The pin 3 in the slot 6 is located at the point that is the nearest to the crankshaft axis. The crankshaft goes on its rotation (fig. 2b) and from the upper dead point and due to the energy of gas pressure, the piston 9 presses through the pin 8, con-rod 7 and pin 3, which slides forward in the slot and advances the crankshaft rotation. It increases greatly the crankshaft rotation arm at the maximum pressure of the operating mixture. The rotational moment on the shaft increases and, respectively, the power and efficiency of the engine increases.

On further crankshaft rotation (fig. 2c), the pin 3 of the con-rod 7 takes the outmost right position in the slot 6 that corresponds to the maximum crankshaft rotation arm and significant gas pressure on the piston at this moment.

 When the piston reaches the position shown in fig. 2d, it changes its direction; the pin 3 is still in the outmost right position of the slot 6.

When the pin reaches the position shown in fig. 2e, it starts to move in the slot 6 in the reverse direction since the bending of the slot wall 6 at the given angle of the shaft rotation can not provide any longer for perpendicularity between the con-rod axis and tangent drawn at the point of the pin 3 contact with the slot 6 wall. At this moment, the piston moves upward mechanically due to the energy transmitted to it by the crank webs during the rotation from 180 to 230° with a slight moderation, whereas the crank-webs move with the steady speed. As a result of it, the outmost left position of the slot 6 “overtakes” the pin.  

4.      Fig. 2f presents the moment of the pin 3 displacement from the right position to the left one in the slot 6.

Fig. 2g presents the position, in which the pin displaced into the outmost left position of the slot 6. The operation cycle completes at the moment, when the position shown in fig.2a is reached.  

5.      The angles shown in fig. 2 can change insignificantly in case of change of the bending and radius of the slot 6 rounding as well as of the height, dimensions and shape of drain and exhaust cylinder ports.  

Patent formula

1.      The crankshaft of the two stroke internal combustion engine containing semi-axis with crank webs connected by the finger differs by the fact that the crankshaft webs are fitted with slots connecting with the floating pin pressed in the con-rod.

2.      As for point 1, the crankshaft differs in the fact that the slots are located along the curve close to the unclosed ellipse line.

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