EP4339420B1 - Double eccentric asymmetrical stroke movement system for four stroke internal combustion engines - Google Patents

Description

• This patent request is a definition of special double eccentric asymmetrical stroke movement system for converting linear motion into rotary motion, or rotary motion into linear motion.
• Practical areas of application can be an internal 4 strokes combustion engines.
• This application is providing a mechanical solution, as design guideline to implement in praxis four strokes "Atkinson cycles" for internal combustion engine wherein the four strokes:

  1.	suction (or intake)	2.	compression
  3.	combustion (or power)	4.	exhaust

  have different stroke lengths and dead centres. By this application can realise a reliable four stroke internal combustion engines to improve their fuel consumption and specific performance.
• 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 by adding only an additional second eccentric and a pair of gears to the design of conventional engines (see the kinematic structure on the Figure 2).
• This system shows (Figure 4 and 7) for transmitting movement between a piston (4) and crankshaft (1), having a connecting rod (3) connected to the piston (4), 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 such that the inner gear completes 3 full relative rotations when the crankshaft is rotating once in the opposite direction. 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).
• Based on this mechanical design the resulting absolute RPM of eccentric : $$\underset{¯}{\mathrm{RPM}\mathit{of}\mathit{eccentric}=}\mathrm{relative}\mathrm{RPM}\mathrm{of}\mathrm{eccentric}+\mathrm{RPM}\mathrm{of}\mathrm{crankshaft}=+3\mathrm{n}-1\mathrm{n}=\underset{¯}{2n}$$
• So, during one revolution of the crankshaft (1), the eccentric (2) makes two complete revolutions in the opposite direction relative to the crankshaft (1).
• The starting angle position (gamma) of the eccentric (2) relative to the crankshaft (1) determines the top dead centres (TDC) positions of piston (Figure 3). So, TDC can be symmetrical if gamma=90°, or asymmetrical, if gamma deviating from 90°.
• In practice this can be set:
1. 1. by connecting the external toothed inner gear wheel (5) to the internal toothed outer gear wheel (6) in different angular position at assembly, and/or
2. 2. by fixing inner gear (5) to the eccentric (2) in different angular position and/or
3. 3. by fixing outer gear (6) to the engine block in different angular position.
• These ways two top dead centres (TDC) for the piston are achieved (Figure 5).
• The position deviation of the bottom dead centres relative to each other can be set mainly by changing the (L2) eccentricity of eccentric (2) versus the (L1) eccentricity of the crankshaft (1). By designing significant bigger (L2) eccentricity than (L1) eccentricity are two different usable bottom dead centres positions of the piston (4) achieved (Figure 4, 5).
Determining the mathematical relationships of this system
• Based on these dimensional characteristics and their effects, the correlation of movements between
• the "alfa" = momentary angular position of crankshaft, and
• the " Lp" = momentary vertical stroke position of the piston (distance from the rotation axis of crankshaft) is determined by following derived mathematical formula to support the designing of this asymmetrical stroke movement system.
1, Mechanical and installation characteristics determine the operation (Figure 4):
• Constant coefficients of the mathematical formula:
  • L1 = eccentricity of crankshaft (1)
  • L2 = eccentricity of eccentric (2)
  • L3 = length of connecting / piston rod (3)
    gamma = the starting angular deviation of the eccentric compared to the zero degree
  • position of the crankshaft (Figure 3).
• Variable angle values determining operation:
  • alfa = momentary angular position of crankshaft
  • beta = momentary angular position of eccentric.
2, Basic geometric definitions:
• Beta = 2 x alfa + gamma, due to resulting RPM of eccentric (2) = doubled RPM of crankshaft (1), $$\mathrm{Momentary}\mathit{vertical}\mathit{length}\mathit{of}\mathit{piston}\left(\mathrm{connecting}\right)\mathrm{rod}=\sqrt{\mathrm{L}{3}^2-{\left(L1\times \mathit{cos}\left(\mathit{alfa}\right)+\mathrm{L}2\times \mathit{cos}\left(\mathit{beta}\right)\right)}^2}$$
• Momentary piston vertical stroke position=L1 x sin(alfa)+L2 x sin(beta)+"momentary piston rod vertical length"
3, Final mathematical formula based on above mentioned three statements:
• The momentary vertical stroke position of the piston "Lp" can be determined depending on the angular position of the crankshaft at all times with the following mathematical formula, if the crankshaft axis point is in the line of the piston pin movement: $$\mathrm{Lp}=\mathrm{L}1\times \sin \left(\mathit{alfa}\right)+\mathrm{L}2\times \sin \left(2\mathit{alfa}+\mathrm{gamma}\right)+\sqrt{\mathrm{L}{3}^2-{\left(L1\times \mathit{cos}\left(\mathit{alfa}\right)+\mathrm{L}2\times \mathit{cos}\left(\mathrm{gamma}\right)\right)}^2}$$
• By usage this mathematical formula for mechanical design, this application seeks to make such a system which adapting for different operating conditions by providing two different level of TDC, and of BDC and 4 different stroke lengths during one revolution of the crankshaft (Figure 5).
• To present the system functionalization and to validate the mathematical formula a practically completed mechanical structure is available as demonstration tool (see a photo about it on Figure 8). There are pictures in the appendices with four important dead centres of demonstration tool, which are linked to by mathematical formula developed stroke diagram (Figure 6).
• This application only includes the design description of one cylinder, but this movement system can be applied accordingly to engines with a higher number and different angular positions of cylinders.
Comparison with other relevant inventions
• This movement system works on a similar principle as the following invention.

  D1	US 2018/163623 A1 (Sokalski Mark)	D2	DE 10 2013 003682 A1 (Gheorghiu Victor)
  D3	DE 10 2015 002385 A1 (Schreiber Georg)	D4	DE 10 2017 010330 A1 (Schreiber Georg)

• The theoretical operating principle (planetary gear system) is similar as the method which defined in D1-2-3-4 applications, but the mechanical realisation is different.
• "A" The crankshaft design of this application externally matches that of traditional 4-stroke internal combustion engines crankshaft in contrast to:
  • D1 patent application where additional power output shaft is needed,
  • D2 patent application where the crankshaft is working not as one fix mechanical unit,
  • D3-4 patent applications do not define mechanical design for practical realisation of crankshaft.
• "B" Complexity of realisation different stroke length (Atkinson cycles):
  • D1 patent application where too many gears (more than 5) and additional mechanical element are needed,
  • D2 patent application has same realisation method,
  • D3 patent application only defining same kinematic principle, without any mechanical design guide for realisation,
  • D4 patent application is using more than two gears and additional inner crank.
• "C" Realisation of different two top dead centres (TDC):
  • D1 patent application is defining high complicates solution for it with too many gears,
  • D2 patent application has same realisation method,
  • D3-4 patent applications are not defining it.
Brief description of the annex (figures, diagrams, technical drawing)

Figure 1

is a perspective view about the operation's principle (hypocycloid),

Figure 2

is a drawing to explain the kinematic structure of movement system and operation,

Figure 3

is a drawing to define the angles for mathematical formula of this movement system,

Figure 4

is a drawing to define mechanical dimensions determining stroke lengths and positions of dead centres,

Figure 5

stroke diagram based on mathematical formula,

Figure 6

is photo collection about the demonstration tool with the 4 dead centres of piston (linked to strokes diagram),

Figure 7

is a technical drawing about embodiment (as design guideline for practical technical implementation) this asymmetrical stroke movement system,

Figure 8

is a Photo about demonstration tool.

• Target of the claim: defining a simple mechanical design concept of an asymmetrical stroke movement system to realise four stroke internal combustion engine with "Atkinson cycle", wherein the piston has four strokes with different stroke lengths and different top centres (TDC) during one revolution of the crankshaft.

Claims (1)

1. n asymmetrical stroke movement system for transmitting linear movement of a piston (4) to a crankshaft (1) having a first eccentric (L1) and being rotatable in an engine block. The stroke movement system having:

   - a connecting rod (3) connected to the piston (4),

   - an outer, internally toothed, gear (6) fixed to the engine block and oriented around the crankshaft (1),

   - an inner, externally toothed, gear (5) rotatably mounted on the eccentric (L1) of the crankshaft (1), wherein said inner gear (5) is engaging the outer gear (6), and wherein the gear ration is 3:1 between the outer gear (6) and the inner gear (5) such that the inner gear completes 3 full rotations when the crankshaft is rotated 1 time,

   - an additional -second- eccentric (2, L2) fixed to said inner gear (5) and configured to rotate together with the inner gear (5), wherein the second eccentric (2, L2) is connected to the connecting rod (3), and wherein two top dead centres (TDC) and two bottom dead centres (BDC) for the piston are achieved when the inner gear (5) with the corresponding second eccentric (2, L2) is rolling one complete turn of the crankshaft inside the outer gear (6), characterized

   in that modification of:

   - the connection point of gears (5, 6) at assembly or/and,

   - the angular position of the outer gear (6) fixing relative to the engine block or/and,

   - the angular position of the inner gear (5) fixing relative to eccentric (2)

   can be adjusted so, as to provide a change in the relative angular positioning (gamma) of the crankshaft (1) and the eccentric (2) so, as to provide asymmetric TDC positions resulting in different levels of the respective TDC.