Double-Eccentric Piston Motion for Asymmetrical Atkinson Strokes
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Solution Overview
Problem
Existing four-stroke internal combustion engines struggle to efficiently implement Atkinson cycles with different stroke lengths and dead centers, leading to suboptimal fuel consumption and performance.
Innovation Solution
A double eccentric asymmetrical stroke movement system is introduced, utilizing an additional eccentric and a pair of gears to convert linear motion into rotary motion, allowing for different stroke lengths and dead centers in a mechanical design that adapts to traditional engines.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a conventional single eccentric mechanism is used, then the mechanical design is simple, but it cannot achieve different stroke lengths and dead centers required for Atkinson cycles
Solution Approach 1:
The single eccentric mechanism is segmented into two independent eccentrics (first eccentric and second eccentric), each controlling different aspects of the piston motion. The first eccentric controls the basic crank motion while the second eccentric provides the additional asymmetrical stroke control, enabling Atkinson cycles without requiring a complete redesign of the entire mechanism.
Solution Approach 2:
The second eccentric is nested within the structure of the first eccentric system. The second eccentric is positioned such that its center lies on the rotation axis of the first eccentric, creating a compact nested arrangement where the smaller eccentric operates within the spatial envelope of the larger eccentric mechanism.
2Use of energy by moving object
If symmetric stroke lengths are used, then the mechanical design is straightforward, but fuel consumption and performance are suboptimal
Solution Approach 1:
The mechanism deliberately introduces asymmetry through the second eccentric with a specific eccentricity distance that is smaller than the first eccentric. This asymmetry creates different effective stroke lengths for the upstroke and downstroke, enabling the Atkinson cycle pattern of long suction/compression strokes and short exhaust/power strokes, thereby improving thermal efficiency and fuel consumption.
3Use of energy by moving object
If multiple eccentrics and gears are added to achieve Atkinson cycles, then fuel efficiency improves, but the mechanical design becomes more complex
Solution Approach 1:
The gear mechanism is merged with the eccentric system such that the gear is mounted on the rotation axis of the first eccentric and transmits rotation to the second eccentric. This integration combines the functions of the gear drive and the dual eccentric mechanism into a unified system, reducing the need for separate mounting structures and control mechanisms.
Solution Approach 2:
The first eccentric serves multiple functions: it acts as the primary crank mechanism for converting rotational motion to reciprocating motion, and simultaneously serves as the mounting base and drive source for the second eccentric through the gear mechanism. This multi-functionality reduces the total number of independent components required.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The system enhances fuel efficiency and performance by enabling reliable Atkinson cycles with varying stroke lengths and dead centers, improving the mechanical design of four-stroke engines.
Implementation Method 1
The system is based on the widely known hypocycloid kinematic (Figure 1). Objective of the present invention to create 'Atkinson cycles' with a simple and feasible mechanical design
Implementation Method 2
an internal toothed outer gear (6) which is mounted and fixed to the engine block, and an external toothed inner gear (5) rotatably mounted on the crank pin of crankshaft (1), wherein said inner gear is engaging the outer gear with a gear ratio 3:1
Implementation Method 3
On the crank pin rotatably mounted an additional eccentric (2) - fixed to the inner gear (5)- and connected to a connecting rod (3) for moving the piston (4). During one revolution of the crankshaft (1), the eccentric (2) makes two complete revolutions in the opposite direction relative to the crankshaft (1)
Data Source
Figure 1
Figure 2~3
Figure 4
AI summary
LKJ motor movement system for four-stroke internal combustion engine includes a second eccentric (2) on the crankshaft (1) instead the piston rod of conventional engines. This second eccentric (2) rotates with double revolutions relative to the crankshaft (1). The doubled revolutions of second eccentric (2) realised by special gear pair (5-6) design. An external toothed gear wheel (5) is fixed to the second eccentric (2) and it rotates together with it. Centrally to the crankshaft (1) there is an internal toothed gear wheel (6), which is fixed to motor block. The second eccentric (2) is actuated by the piston (4) through the piston rod (3), in parallel the crankshaft (2) is actuated by second eccentric (2) through the gear-pair (5-6), or vice-versa depend on type of stroke. With this mechanical design, a new movement system was created, where the piston makes four strokes with different lengths and dead centres during one revolution of the crankshaft. This enables the further development of four-stroke internal combustion engines in terms of reducing fuel consumption and increasing efficiency. Although this invention has been explained in relation to its preferred embodiment as mentioned above, it is to be understood that many other possible modifications and variations can be made without departing from the scope of the present invention. It is, therefore, contemplated that the appended claims will cover such modifications and variations that fall within the true scope of the invention.