Symmetric Hypocycloidal Engine

Symmetric Hypocycloidal Engine (HS Engine) is an internal combustion engine with the crankshaft replaced by a symmetric hypocycloidal mechanism. Consequently, in this engine there is no friction between the piston and the cylinder. Also, because the mechanism is symmetric, it is small and lightweight.

Fuel efficiency
Formal status


SH Engine leverages the symmetric hypocycloidal mechanism of conversion of reciprocating motion into rotary motion. In this mechanism, there is a main wheel, a planetary wheel and a connecting rod. The planetary wheel is eccentrically embedded in the main will and pivotally connected to a forked connecting rod on both sides of the main wheel. 

The mechanism makes the piston move in the cylinder frictionlessly. 

Because of the symmetry of the mechanism, it is small and lightweight. 

The mechanism can also be applied in air compressors.


Figure 1. Symmetric Hypocycloidal Engine

Components of the invention (see Fig. 1):
1 – cylinder
2 – piston
3 – connecting rod
4 – shaft
5 – shaft wheel
6 – stationary ring
7 – main wheel with teeth (7′) and counterweight (7”)
8 – planetary wheel with teeth (8′) and counterweight (8”)

Summary of the invention: The movement of the piston (2) causes the planetary wheel (8) to rotate simultaneously about its axis, and about the axis of the main wheel (7), the movement of the planetary wheel (8) rotates the main wheel (7). The main wheel (7) is coupled with the shaft (4). The connecting rod (3) is pivotally connected to the planetary wheel (8) on both sides of the main wheel (7). Therefore, the mechanism can be lightweight and the balance weights can accordingly be lightweight. In addition, the piston moves in the cylinder with virtually no friction, which makes the engine efficient.

Figure 2 below shows the subsequent phases of the engine movement.

Figure 2. Subsequent phases of the engine movement

Other applications of the invention include air compressors.

Fuel efficiency

In a traditional internal combustion engine, the energy of the fuel is divided into effective work, internal friction of the engine and exhaust heat, in the proportions of 40-20-40. About 3/5 of the friction is between the piston and the cylinder. The symmetric hypocycloidal engine eliminates this friction almost completely, so it saves about 20% fuel. 20% = 3/5 * 20% / (40%+20%).

Formal status

A patent for this invention is pending.

Scroll to Top