Internal-combustion engines – Multiple cylinder – Cylinder offset from crankshaft axis
Patent
1998-01-29
1999-11-16
Wolfe, Willis R.
Internal-combustion engines
Multiple cylinder
Cylinder offset from crankshaft axis
1231971, 123DIG8, 74 50, 92 68, F02B 7532, F02B 7524, F16H 2116
Patent
active
059838450
DESCRIPTION:
BRIEF SUMMARY
FIELD OF TECHNOLOGY
The present invention relates to a rotary drive system and an engine, more precisely relates to a rotary drive system and an engine, which convert linear movement into rotation.
BACKGROUND OF TECHNOLOGY
Recipro-engines and hydraulic motors, for example, have been used as mechanisms for converting linear movement into rotation. In the conventional converting mechanisms, thrust force of a piston, which linearly moves in cylinders, is converted into rotation of a crank shaft.
The conventional mechanisms, e.g., the recipro engines, the oil motors, the have following disadvantages. Firstly, the piston and the crank shaft are connected by a connecting rod. One end of the connecting rod is pivotably connected with the piston, so they mutually incline while in operation. The connecting rod and the crank are also pivotably connected by a piston pin, so they mutually incline while in operation. When the connecting rod inclines with respect to the piston and the crank shaft, 100% of the thrust force of the piston cannot be transmitted to the crank shaft. Namely, component force in the tangent direction of the crank shaft, which is divided from component force of the thrust force toward the connecting rod, is transmitted to the crank shaft, so that transmitting loss is great. Thus, the rotary torque of the crank shaft is quite lower with respect to the linear thrust force of the piston; efficiency of converting the linear thrust force into the rotary torque is low.
Secondly, the crank shaft rotates at fixed speed when the linear movement of the piston is converted into the rotation of the crank shaft, so the speed of the piston is faster near an upper dead point and slower near a lower dead point. Thus, vibration is apt to happen. This point will be explained with reference to FIGS. 20 and 21.
FIG. 20 is an explanation view showing an example of the conventional crank mechanism including the connecting rod.
In this example, stroke "S" of the piston 110 is 40 mm; length of the connecting rod 120 is 50 mm. A connecting section 125 of the crank 130 and the connecting rod 120 are located at a 0.degree. position "L", which is the furthest position from a cylinder 140, when the piston 110 is at the lower dead point P.sub.1. If the crank 130 turns 90.degree. from the 0.degree. position "L", the connecting section is at a 90.degree. position "M"; the connecting section is at a 180.degree. position "H", when the crank 130 turns 180.degree. and the piston 110 locates at the upper dead point P.sub.2.
FIG. 21 is a graph showing relationship (a solid line) between the rotational angle X.sub.c (degree) of the crank 130 and a position Y.sub.p (mm) on the stroke of the piston 110 of the example shown in FIG. 20. Note that, a one-dot-chain line shows a sine wave.
When the crank 130 is at the 0.degree. position "L", the piston 110 is at the lower dead point P.sub.1, so the position Y.sub.p (mm) of the piston 110 is 0 mm; when the crank 130 is at the 180.degree. position "H", the piston 110 is at the upper dead point P.sub.2, so the position Y.sub.p (mm) of the piston is 40 mm.
When the piston 110 moves from the lower dead point P.sub.1 to the upper dead point P.sub.2, the crank 130 turns from the 0.degree. position "L" to the 90.degree. position "M", and the piston 110 moves 15.83 mm. When the crank 130 turns from the 90.degree. position "M" to the 180.degree. position "H", the piston 110 moves 24.17 mm. Namely, the speed of the piston 110 is faster near the upper dead point P.sub.2 and slower near the lower dead point P.sub.1. So it is difficult to stably rotate the crank shaft, and a vibration is likely to occur. Near the upper dead point P.sub.2, fuel is ignited and burnt, but the speed of the piston is fast, so that it is difficult to ignite at proper timing. With this untimely ignition, the efficiency of the conventional crank mechanism is limited, and noise cannot be reduced.
To improve above described disadvantages, the inventor of the present invention has invented a rotary drive system (Japanese Patent
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Hairston Brian
Wolfe Willis R.
Yugen Kaisha Sozoan
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