Mechanisms With Rigid Memory

E-mail: rvvpetrescu@gmail.com Abstract: Along with gears, distribution mechanisms are the most widely used mechanical transmissions used over the past 300 years and will continue to be the most widespread in all industrial fields but also in other technical areas. For this reason, it was considered necessary this work, which tries to add a brick to the permanent construction of rigid memory mechanisms used especially as distribution mechanisms for motor vehicles. The paper presents some essential aspects of the synthesis of the distribution mechanisms.


Introduction
An engine mechanism is a mechanism of a force machine which, in the case of an engine machine, transmits and eventually transforms the movement caused by the internal energy transformation of the working agent (combustion gases, steam, compressed air) into the motor shaft, or in the case of generating machines (e.g., piston compressors), vice versa, from the shaft to the working agent.
In motor machines, the mechanical work is initially obtained in the form of reciprocal movement of the piston in the cylinder. The motor mechanism turns this movement into a continuous rotary motion of the shaft.
For standard internal combustion engines, the engine is based on a crank-shaft mechanism. By extension of language, the motor mechanism means not only moving parts but also fixed ones to the frame (chassis, etc.), even if they move with the vehicle it propels (motor vehicle, locomotive, airplane, boat, etc.).
Components considered to be fixed are: The flywheel, along with the torsion oscillator.
The distribution mechanism is an auxiliary system of the internal combustion engine, the steam engine having the function of correlating the filling of the engine cylinders with fuel, steam, air and flue gas or air.
The distribution mechanism is used in almost all four-stroke internal combustion engines, except for the Wankel engine and two-stroke engines.
Depending on the type of engine to which it is applied, the distribution may be for four-stroke or twostroke engines.
The distribution to two-stroke engines, in general, is without valves and has window-in-cylinder cylinders that are closed or open by moving the piston, which is also called light distribution. Two-stroke engines, especially those with compression ignition, have only intake or exhaust valves.
The four-stroke engine distribution uses a valve mechanism that can be operated mechanically, pneumatically, magnetically or hydraulically. In most cases (mechanical, hydraulic), the valves are driven by spikes or directly by the camshaft.
Following the position of the valves, the distribution mechanism may be with side valves, with valves in the head, or with a mixed distribution mechanism.
Side valve distributor mechanism (SV; eng., Side Valves) for example small engines with a narrower (low) cylinder head. In this case, the valves are in the engine block or the cylinder.
Distributor mechanism with valves in the head, with this mechanism the valves, are mounted in the cylinder above the piston.
Mixed distribution mechanism when the valves are also mounted in the engine block and cylinder head.
After camshaft mounting, there is a camshaft mounted camshaft mechanism and camshaft mounted on the cylinder head.
On the crankshaft mounted camshaft, the valves are hinged by hinges, their rods and tilts (OHV, eng., Over Head Valves).
On camshaft mounted Overhead Camshaft (OHC), the valves are driven by swinging or direct valve engagement.
After engaging the camshaft: Belt Chain Gear The distribution system of an internal combustion engine for automobiles is the set of all parts that allow for the regular change of gas from the cylinders. To function, an internal combustion engine needs fresh air or an air-fuel mixture to be introduced into the cylinders instead of residual flue gases to be discharged. Briefly, the distribution system provides fresh air/mixture into the cylinders and flue gas outlet.

Components of the Distribution System (Fig. 1)
Four-stroke engines have valve distribution systems. There are also distribution systems with lights/slides (two-stroke engines) or drawers (racing cars) or combined, lights and valves (two-stroke engines):

Types of Distribution Systems
Depending on the position and number of cams, the distribution systems can be: • OHH (OverHead Valves) • OHC (OverHead Camshaft) • DOHC (Double Overhead Camshaft) • OHV distribution system This type of distribution system has the camshaft in the engine block. The shaft drive is usually made with a metal chain. In addition to the camshaft sprocket distribution systems, the OVH distribution also contains pushing rods (Fig. 2).
1-camshaft 2-cleats 3-pushing rods 4-rocker 5-valve spring 6-valve The camshaft (1) is driven by the crankshaft of the engine and acts on the tillers (2). By means of pushing rods (3) the profile of the cams deflection (4) opens the valves (6). The valves are held in the seat by the helical springs (5).

OHC Distribution System
Most engines that fit modern cars are fitted with a camshaft. If each cylinder has two in take and two exhaust valves, the distribution system will have two camshafts (DOHC) (Fig. 3).
Chassis Camshaft Shaft Distribution System (DOHC): 1-cam (camshaft) 2-follower 3-valve spring 4-valve stem 5-Exhaust Gallery 6-valve support 7-cylinder/combustion chamber  OHC distribution systems, as compared to OHV, do not have pushing rods. Actuation of the valves is done directly by the camshaft by means of taps and coulters. If the distribution system has 4 valves per cylinder in the cylinder head, there are two camshafts acting directly on the DOHC.
The chassis camshaft (OHC, DOHC) is the number of smaller parts. The lack of pushrods and cogs increases the durability of the system, reduces vibrations and allows higher speeds.

Valves
The valve is made up of two parts, the valve stem which obstructs the channel in the cylinder head and the valve stem receiving the movement, guides the valves during the movement and evacuates some of the heat transferred to the valve (Fig. 4).
The valves open inside the cylinder to take advantage of the pressure of the gas while it is closed (better sealing). The intake valves, compared to the exhaust ports, have the larger diameter because the intake port is larger. This favors the better filling of the fresh gas cylinder during intake. In order to withstand intense mechanical and thermal stresses, the valves are made of high alloy steel.
The camshafts are driven by the crankshaft of the engine by means of a toothed belt (belt distribution) or a metal chain (chain distribution). The trees are made of alloy steel or alloy cast iron. The canvas between the cams and the sticks is always lubricated with engine oil (Fig. 5).
Because each valve opens once on a complete engine cycle (two crankshaft rotations), the camshaft speed is half that of the crankshaft.
The shape of the cams determines the length and opening height of the valves. The distribution system in which the opening height and the opening time of the valves are fixed, invariable is called a fixed distribution. A distribution system that can vary the length or the opening height of the valves is called variable distribution.

Cleats
The spool is the piece that is driven directly by the camshaft. To reduce noise in operation and to compensate for the heat play, hydraulic tightening is used. The thermal play is the distance between the moving piles of the distribution system (pushing rod-OHV or OHC camshaft), which varies depending on the temperature of the parts. The heat play increases with the wear of the parts and has a negative impact on the noise and reliability of the distribution system (Fig. 6).  The cam mechanisms specifically transform a uniform rotational motion into alternating non-uniform rotational motion or alternate linear motion. In these mechanisms, in general, the movement is transmitted from the cam guide member to the driven member via direct contact. It rarely happens that the cam element is a driven or fixed element. In the latter situation, the stick picks up both movements, as is the case with the mechanism that controls the vertical drift of the scissor tool sleeper: fixed cam, punch oscillating, with its rotation motion in translation.
The cam mechanisms are widespread in design mechanical engineering because the cam profile can have almost any shape, depending on the moving law that is desired for the stick.
Between the cam and the barrel, there is a superior coupling with no more than two degrees of freedom (rolling and slipping) for the case of the flat cam and no more than five degrees of freedom for the space cam case. However, there may be constraints, so that the number of degrees of freedom allowed by the kinematic couple can be reduced.
The simplest cam mechanism (Fig. 7) consists of the following kinematic elements: the cam (1), the stick (2) and the roller (3). The roll is a kinematically passive element that is introduced to reduce cam and punch wear, as well as to reduce frictional losses by turning the slip into rolling friction.

Materials and Methods
In the Fig. 8 it presents the kinematics schema of the classic distribution mechanism, in two consecutive positions; with a interrupted line is represented the particular position when the follower is situated in the most down plane, (s = 0) and the cam which has an orally rotation, with constant angular velocity, ω, is situated in the point A 0 , (the recordation point between the base profile and the up profile, particular point that mark the up begin of the follower, imposed by the camprofile); with a continue line (green) is represented the superior couple in someone position of the up phase.
From initial position (x F ) to someone position (x M ) the cam (camshaft) was rotated with an ϕ angle. In this time the position vector r = r A was rotated (in relation to the mobile axis x M ) with the θ angle, which is a sum between ϕ and τ (where τ is the transmission angle who occurs between the initial, vertical, fix axis and the position vector r = r A . The cam or camshaft movement is given by θ angle and the position vector r movement is characterized by the θ angle (this is all the main problem of the classical distribution mechanism). In any position point (the contact point between cam and tappet) is given by the coordinates r and θ (polar) or x A , y A (Cartesian), for tappet in a fix system and for the cam in a mobile system.
The point A 0 , which marks the initial couple position, represents in the same time the contact point between the cam and follower in the first position. The cam has an angular velocity ω (the camshaft angular velocity).
Cam is rotating with the velocity ω describing the angle ϕ, which show how the base circle has rotated in the orally sense, (with the camshaft together); this rotation can be seen on the base circle between the two particular points, A 0 and A 0i .
In this time the vector r A = OA (which represents the distance between the centre of cam O and the contact point A), has rotating (trigonometric) with the τ angle. If one measures the θ angle, which positions the general vector r A in function of the particular vector, r A0 , it obtains the base relation noted with (0): where, r A is the module of the vector A r and θ A represents the phase angle of the vector A r . The rotating velocity of the vector A r is A ɺ θ which it's a function of the angular velocity of the camshaft, ω and a rotating ϕ angle, (by the movement laws s(ϕ), s'(ϕ), s''(ϕ)).
The follower isn't acted directly by the cam, by the angle, ϕ and by the angular velocity ω; it's acted by the vector A r , which has the module r A , the position angle θ A and the angular velocity A ɺ θ . From here result a particular (dynamic) kinematics, the classical kinematics being just a static and approximate kinematics.
1 v = the cam velocity; which is the velocity of the vector A r , in the point A (that is not a fix point on the cam, but it is a point which is moving on the cam); now the classical relation (1) become an approximately relation and the real relation takes the form (2): The velocity 1 v AC = is separating in the velocity 2 v BC = (the follower velocity which act in its axe, on a vertical direction) and 12 v AB = (the slide velocity between the two profiles, the sliding velocity between the cam and the follower, which works by the direction of the commune tangent line of the two profiles in the contact point).
Usually the cam profile is synthesis with the AD = s' known, for the classical module C and one can write the relations (3-7): Now, the follower velocity isn't , but it's given by the relation (9). At the classical distribution mechanism the transmitting function D, is given by the relations (8): Determination of the sliding velocity between the two profiles in contact is made by the relation (10): The angles τ (and then θ A ) will be determined with its first and second derivatives.
The τ angle has been determined from the triangle ODA ( Fig. 8) with the relations (11-13): One derives relation (11) in function of ϕ angle and it obtains the expression (14): A A r s s s s s r s r r s s τ τ The relation (14) will be written in the form (15): s r s s s s r s s s r s s r s s From the relation (12) one extracts the value of cos τ, which will be introduced in the left term of the expression (15); then one reduces s''.s' 2 from the right term of the expression (15) and it obtains the relation (16): After some simplifications one obtains finally the relation (17) which represents the expression of τ': s r s s r s s Now, when it was explicitly τ', one can determine the next derivatives. The expression (17) will be derived directly and it can be obtained for begin the relation (18): s r s s s s s r s s s r s s r s s s s r s s One reduces the terms from the first bracket of the numerator (s'.s'') and then one draws out s' from the fourth bracket of the numerator and one obtains the expression (19): s r s s s r s s s s r s s r s s r s s Now, one can calculate θ A , with its first two derivatives, A ɺ θ and A ɺɺ θ . We write θ and not θ A , to simplify the notation. Now, one can determine (20), or relation (0): One derives (20) and it obtains the relation (21): One makes the second derivative of (20) and the first derivative of (21) and it obtains (22): One can write now the transmitting functions, D and D' (at the classical module C), in the forms (23-24): The follower velocity (relations from system 25), need the expression of the transmitted function, D: Where: For the classical distribution mechanism (Module C), the variable w is the same with A ɺ θ (see the relation 25). But at the B and F modules (at the cam gears where the follower has roll), the transmitted function D (and w), takes some complex forms. Now, it can determine the acceleration of the follower (27): In the Fig. 9, it can be seen the kinematics classic and dynamic; the velocities (a) and the accelerations (b).
To determine the acceleration of the follower, are necessary s' and s'', D and D', τ' and τ''.
The kinematics dynamic diagrams of v 2 (obtained with relation 25, Fig. 9a) and a 2 (obtained with relation 27, Fig. 9b), have more a dynamic aspect than a kinematic one. It has used the movement law SINE, a rotation velocity at the crankshaft, n = 5500 [rpm], an up angle, ϕ u = 75 [deg], a down angle ϕ d = 75 [deg] (identically with the up angle), a ray at the basic circle of the cam, r 0 = 17 [mm] and a maxim stroke of the follower, h T = 6[mm]. Anyway, the dynamic is more complex, having in view the masses and the inertia moments, the resistant and motor forces, the elasticity constants and the amortization coefficient of the kinematics chain, the inertia forces of the system, the rotation velocity of the camshaft and the variation of the camshaft velocity, ω with the cam ϕ position and with the rotation speed of the crankshaft, n.

Plotting (Synthesis) of Classical Cam Profile
In xOy fixed system, Cartesian coordinates of point A of contact (of the tappet 2) are given by the position vector r A projections on the axes Ox Oy respectively and analytical expressions expressed by the relational system (28): Above, in the Fig. 10 it can be seen the cam profile to the classical module C, for a law cosine, h = 6 [mm], r 0 = 13 [mm], η = 6%.

Results
In the Fig. 11  The δ pressure angle (that occurs between normal n gone through the contact point A and a vertical line) has the known size given by the relations (2.5-2.7): (2.7) The vector A r can be determined directly with the relations (2.8-2.9): It can directly determine the angle α A (2.10-2.11): It can be now drawn directly the cam profile using polar coordinates r A (known, see relation 2.9) and θ A (which is determined by relations 2.12-2.17): In the Fig. 12 it can be seen for the module B a cosine law cam profile calculated with parameters: . One has obtained in this mode a high yield for a mechanism with cam: η = 39%. It can be obtained the same yield ( Fig.  13) with decreased stroke and up angle: For such distribution mechanism works normally we must use the special adjustment valve spring: x 0 = 9 [cm], k = 500000 [N/m]. Where k is the valve spring elastic coefficient and x 0 is the valve spring preload. It can be obtained a higher yield (Fig. 14) with the next parameters: . Although spring used is extremely hard to have a good dynamic in operation (Fig. 15), there's need to reduce its camshaft rotation speed three times. But for such distribution mechanism may work must be used a triple cam.   r r r r r r r r r r

Synthesis of the Distribution Mechanism Module F
In the Fig. 16 one can see the module F, with rotation cam and rotated tappet with roll, in initial position and in some one position.
A study very precisely (exactly) is possible only when we analyze what happens in point A (the point of contact between cam and the roller of the tappet). Point A is defined by the vector of length (module) rA and θ A position angle, measured from the axis Ox and or α Α angle, measured from the axis OD (Fig. 16).
In the same mode is defined position of the point B (roll center), by the vector , is forming an angle µ. The angle α 0 defines the position, basic (initial) of the vector r A in ODB 0 right triangle, as measured from the axis OD. The rotation of the cam (the shaft distribution), given by the ϕ angle, is measured from the axis Ox, to the vector. As the camshaft rotates with ϕ angle, the vector is rotated by the angle θ A and between the two angles θ A and ϕ there is a mismatch (a phase shift) which is noted in Fig. 16 with γ; γ phase shift occurs and between α A and α 0 angles, which helps us to determine the exact value of its. The length (radius) of the tappet, DB = b, in the initial position DB 0 makes with OD axis the angle ψ 0 constant, which can be determined easily together with α 0 from the triangle ODB 0 (with: OD = d, DB = DB 0 = b, OB 0 = r 0 +r b known; where r 0 is the radius of the basic circle on the rotary cam and rb is the roller radius of the follower). From initial position until the current position, the follower rotates around the point D with a known ψ angle. This ψ angle, is given by the law of motion of pusher and is a function of the ϕ angle. ψ is known together with its derivatives: ψ', ψ'', ψ'''. In general it is easier to express the movement of the follower in function of axis OD, so occurs the angle ψ 2 = ψ 0 +ψ (with: 2 2 ' ', " " ψ ψ ψ ψ = = ). From ODB triangle, with known lengths OD = d, DB = b and ψ 2 angle, one determines the length OB = r B , the DOB = α B angle and the OBD = β 2 angle (Fig. 17). Angle B sought, with angles β 2 and τ, totals 180 [deg]; and τ+δ = 90 [deg]; with delta known, results τ and the B angle. Now, with r B , r b and B known (from the triangle OBA) we can determine r A and µ.

Synthesis of the Cam Profile
Now it can make the synthesis of the cam profile with the next relationships (3.1-3.4): To do this, it must determine first the pressure δ angle.

Determination of the Pressure δ Angle
Now one presents shortly one known method to determine the pressure angle δ at the rotary cam and rocking tappet with roll (Module F, Fig. 18).
The pressure angle is defined between two straight lines: n-n and t-t (the line n-n, pass through the points A and B and is perpendicular in A at the two profiles in contact; the line t-t, pass through the point B and is perpendicular in B on the line DB which represent the tappet axis).
One builds (scale) the speed triangle rotated with 90 [deg] (Fig. 18); the cam velocity in B (vB 1 ) appears along the BO, oriented from B to O, the reduced velocity of the tappet in B point (vB 2 ) appears along the BD, oriented from B to b 2 and the sliding between profiles velocity in the point B (vB 2 B 1 ) appears along the n-n line, oriented from O to b 2 .
It takes the pole of the fold ( From the ODb 2 triangle, one determines the length Ob 2 , (relation 3.6): With the known lengths one can determine now the trigonometric functions of the δ pressure angle, with the relationships (3.7-3.9):  Fig. 19: Determination of the additionally pressure angle α

Determination of the Pressure α Angle
Further α pressure-angle is determined (where α is an additional pressure-angle), to the rotary cam and rotating follower with roll (Module F). This angle appears between the direction n-n and right segment AA', perpendicular in A on OA (Fig. 19).
From some triangle OAB was expressed and OAB angle (Fig. 19). From the angle OAB directly subtract 90° and get extra pressure α angle.

Basic Kinematics of Module F
Below are presented a few parameters determining the kinematics (which constitutes the basis of this mechanism); relations: 3.21-3.56: 2 2 2 sin( ) sin cos sin cos 2 2 2 cos( ) cos cos sin sin Relations to Draw (Synthesis) the Cam Profile, to the Module F Next few cinematic parameters are determined by which cam profile can be traced directly (to the rotating cam and rocker follower with roll); relations 3.57-3.64:

The Cam Profile Module F of Law C4P
In the Fig. 20 one can see the cam profile for an original law called by author C4P, which support a rotation speed of the drive shaft of 40000 [rpm], compared with the classical distribution who support a maximum drive shaft rotation speed of 5000-6000 [rpm].

The Dynamic Coefficient D
The dynamic coefficient is expressed with relation (3.65), where has the expression (3.66) and is given by the expression (3.67):

Synthesis of the Distribution Mechanism Module H
In the Fig. 21 one can see the module H, with rotation cam and rotated plane tappet, in initial position and in some one position.
For general use kinematic relations are inserted 4.1-4.4: In the Fig. 22 one can see and the velocities and the forces of this type of distribution mechanism.
In the Fig. 23 it can see a cam profile at the module H (with rotation cam and rotating plate follower), for a law sine.
In the Fig. 24 it can see a cam profile at the module H (with rotation cam and rotating plate follower), for a law C4P. The phase angle is ϕ u = ϕ c = 70 [deg]; core radius has value r 0 = 20 [mm]. This profile support a drive shaft rotation speed of 30000 [rpm].

Discussion
Rigid memory mechanisms, commonly known as cam and follower mechanisms, have revolutionized the world several times. The first time they have radically changed the face of the world when they were massively introduced to automatic tissue machinery, in the Netherlands in the 18th century and then immediately developed in England and then all over the world. Tissue wars as these machines were called at that time managed to mark a turning point for humanity in its development, as they quickly changed the way of production from weaving women to automated tissue machines, following a scientific-technical revolution, social ...
The first valve mechanisms appeared in 1844, being used in steam locomotives; they were designed and built by the Belgian mechanical engineer Egide Walschaerts.
The first cam mechanisms are used in England and the Netherlands in the tissue wars.
In 1719, in England, some John Kay opens in a fivestory building a spinning facto plant. With a staff of over 300 women and children, this would be the world's first factory. He also becomes famous by inventing the flying sail, which makes the tissue faster. But the machines were still manually operated. It was not until 1750 that the textile industry was to be revolutionized by the widespread application of this invention. Initially, the weavers opposed it, destroying flying sails and banishing the inventor. By 1760 the wars and the first factories appeared in the modern sense of the word. It took the first engines. For over a century, the Italian Giovanni Branca had proposed the use of steam to drive turbines. Subsequent experiments were not satisfying. In France and England, brand inventors, like Denis Papin or the Worcester Marquis, came up with new ideas. At the end of the seventeenth century, Thomas Savery had already built the "friend of the miner", a steam engine that put into operation a pump to remove water from the galleries. Thomas Newcomen has made the commercial version of the steam pump and engineer James Watt develops and adapts a speed regulator that improves the engine's net. Together with Mathiew Boulton, he builds the first steam-powered engines and in less than half a century, the wind that fed for more than 3,000 years, the propulsion power at sea now only inflates pleasure boats. In 1785 came into operation, the first steam-powered steamer followed quickly by a few dozen.
The first distribution mechanisms occur with fourstroke engines for cars.
In 1680, Dutch physicist Christian Huygens designs the first internal combustion engine.
In 1807, Swiss François Isaac de Rivaz invented an internal combustion engine that uses a liquid mixture of hydrogen and oxygen as fuel. However, Rivaz's engine for its new engine has been a major failure, so its engine has gone dead, with no immediate application.
In 1824, English engineer Samuel Brown adapted a steam engine to make it work with gasoline.
In 1858, Belgian engineer Jean Joseph Etienne Lenoir invented and patented two years later, practically the first real-life internal combustion engine with spark-ignition, liquid gas (extracted from coal), a two-stroke engine . In 1863, the Belgian Lenoir is the one who adapts to his engine a carburetor, making it work with oil (or gasoline).
In 1862, the French engineer Alphonse Beau de Rochas first patented the four-stroke internal combustion engine (but without building it).
It is the merit of the German engineers Eugen Langen and Nikolaus August Otto to build (physically, practically the theoretical model of the French Rochas), the first four-stroke internal combustion engine in 1866, with electric ignition, charging and distribution in a form Advanced.
Ten years later (in 1876), Nikolaus August Otto patented his engine.
In the same year (1876), Sir Dougald Clerk, he puts the two-stroke engine of Belgian Lenoir (bringing it to the shape known today).
In 1885, Gottlieb Daimler arranges a four-stroke internal combustion engine with a single vertical cylinder and an improved carburetor.
A year later his compatriot Karl Benz brings some improvements to the four-stroke engine. Both Daimler and Benz were working new engines for their new cars (so famous).
In 1889, Daimler improves the four-stroke internal combustion engine, building a "two cylinder in V" and bringing the distribution to today's classic form, "with mushroom-shaped valves." In 1890, Wilhelm Maybach built the first fourcylinder four-cylinder internal combustion.
In 1892, German engineer Rudolf Christian Karl Diesel invented the compression-ignition engine, in short the diesel engine.
Today, the models of distribution mechanisms have greatly diversified, being vital to internal combustion engines mounted on cars, which today are produced annually in over 60-70 million extra copies and the car fleet is more than a billion after 2010 years.
Essential changes to this mechanism have been attempted by replacing it with induction coils that move a linear spike, but the forces and high moments in the system have caused these electromagnetic mechanisms to break rapidly after a small number of cycles, not having the resistance of the classic distribution mechanism created in 1866 by Otto.
The synthesis of these types of distribution mechanisms can be done shortly by Cartesian coordinates, but for the determination of these coordinates, we also need trigonometric parameters. This synthesis method, which is based on trigonometric parameters (in a large proportion), can be called a trigonometric synthesis method. With the internal combustion engine, there is a great loss of power through the distribution mechanism, which is why we must try to improve the functionality of this mechanism.
Based on the relationships presented, it is still possible to determine both the analysis and the synthesis of the dynamic mechanism.
The short relationships presented in this study are therefore of essential nature, as they can then generate dynamic relationships.
As long as we produce electricity and heat by burning fossil fuels, it is useless to try to replace all electric motors as electricity and the pollution will be even greater.
However, it is good to continually improve thermal motors to reduce fuel consumption.
With the internal combustion engine, there is a great loss of power through the distribution mechanism, which is why we must try to improve the functionality of this mechanism.
The modular combustion chamber has a unique design of the valve actuator. The valve springs exert great forces to ensure their rapid closure. The forces for their opening are provided by camshaft driven camshafts.
Economy: Velcro and cams are large, ensuring smooth and precise action on the valves. This is reflected in low fuel consumption.
Reduced pollutant emissions: The accuracy of the distribution mechanism is a vital factor in engine efficiency and clean combustion.
Cost of operation: An important benefit brought by the size of the tachets is their low wear rate. This reduces the need for adjustments. Valve operation remains constant over a long period of time. If adjustments are required, they can be made quickly and easily.
Today, more than ever, we want to eliminate internal combustion engines or even thermal ones that have been carrying us for over 200 years and replacing them with other more modern engines.
Water engines have the best note on this, but research in the field is not much desired by some of the planet's leaders, these projects not being sponsored enough and fair. A water engine actually burns hydrogen out of the water by modern methods, with no much-extracting energy, which makes water an ideal energy storage facility. By combustion, water is naturally reclaimed, the burning of hydrogen is complete and free of noxious, unlike fossil fuels, petroleum and gaseous fuels.
When burning hydrogen, it is always preferable to have a thermal cell burner instead of a classic engine because hydrogen burns ten times faster than conventional fuels and also presents the risk of explosion.
For this reason, the burning of stored hydrogen or the extracted directly from the water will always be done in special burners, which produce heat transformed by chemical processes into electrical energy that loads some modern accumulators so that the solution is automatically conducive to the final use of some motors electric on the vehicle in question, so the thermal engine disappears from the equation when talking about hydrogen fuel or water.
And from the nostalgia for keeping the thermal engines, but especially from the desire of oil and gas magnates to preserve their priorities on the extracted gas and their oil, it is still undesirable to move on to such a modern solution, with water.
The problem what will happen with a park of motorized cars on classic fuels, a park of over one billion cars, is not as hard as it may seem, because no ordinary man will buy such classic cars anymore, if will occur cars with water, cheap and with great capabilities.
We notice that higher amounts are paid for research on permanent magnetic motors, which for more than 20 years since they appeared did not evolve too much due to the rapid demagnetization of the materials used.
It seems to be preferable for scientific research to focus on the slippery ground from the very beginning, just as oil and gas will still be the most desirable for motorists in this mode.
The simple electric engine develops slowly with the fuel cell models.
Its problems are still high because electric cars are still expensive, heavy to load and can not be loaded in every place and the loading time is still high, but especially the autonomy of such cars is still small compared to the classical ones with fossil fuels.
Nowadays, new oil resources and new gas reserves have also emerged, considering the shale gases (of depth that can be extracted today), so that the planet's gas reserves have increased from 40-50 years to about 2000 years.
The burning of hydrogen is clean, that of gas burning is quite complete and yet it is keeping the very polluting gasoline and diesel.
As very large gas reserves have been discovered, they are now being transformed into pollutants, gasoline and diesel, in very large processing plants (three are already working at high capacity), although they will then be required by limitation rules polluting by the production of sophisticated devices (Euro 6) that produce large losses and anyway the pollution remains. It would be easier to switch to gas burning than to convert gas into gasoline and diesel and then introduce a Euro 7 to filter and limit the pollution caused by gasoline and diesel. Current world policies are completely contradictory, convert non-polluting gas into diesel and then impose anti-pollution rules on diesel fuel.
Under these circumstances, it is still necessary to further study and improve the distribution systems of thermal engines to limit the levels of pollutant emissions in this way.

Conclusion
The synthesis of these types of distribution mechanisms can be done shortly by Cartesian coordinates, but for the determination of these coordinates, we also need trigonometric parameters.
This synthesis method, which is based on trigonometric parameters (in a large proportion), can be called a trigonometric synthesis method. With the internal combustion engine, there is a great loss of power through the distribution mechanism, which is why we must try to improve the functionality of this mechanism.
Based on the relationships presented, it is still possible to determine both the analysis and the synthesis of the dynamic mechanism.
The short relationships presented in this study are therefore of essential nature, as they can then generate dynamic relationships.
As long as we produce electricity and heat by burning fossil fuels, it is useless to try to replace all electric motors as electricity and the pollution will be even greater.
However, it is good to continually improve thermal motors to reduce fuel consumption.
With the internal combustion engine, there is a great loss of power through the distribution mechanism, which is why we must try to improve the functionality of this mechanism. Under these circumstances, it is still necessary to further study and improve the distribution systems of thermal engines to limit the levels of pollutant emissions in this way.
In addition, these mechanisms are also used for mechanical transmissions everywhere, for automated machines, for robotics and mechatronization, as well as for medical devices.

Acknowledgement
This text was acknowledged and appreciated by Dr. Veturia CHIROIU Honorific member of Technical Sciences Academy of Romania (ASTR) PhD supervisor in Mechanical Engineering.

Ethics
This article is original and contains unpublished material. Authors declare that are not ethical issues and no conflict of interest that may arise after the publication of this manuscript.
Antonescu, P., M. Oprean and F.I.T. Petrescu, 1985a. Contributions to the synthesis of oscillating cam mechanism and oscillating flat stick. Proceedings of the 4th International Symposium on Theory and Practice of Mechanisms, (TPM' 85), Bucharest. Antonescu, P., M. Oprean and F.I.T. Petrescu, 1985b. At the projection of the oscillate cams, there are mechanisms and distribution variables. Proceedings of the 5th Conference of Engines, Automobiles, Tractors and Agricultural Machines, (AMA' 58), I-Motors and Cars, Brasov. Antonescu, P., M. Oprean and F.I.T. Petrescu, 1986. Projection of the profile of the rotating camshaft acting on the oscillating plate with disengagement. Proceedings of the 3rd National Computer-aided Design Symposium in the field of Mechanisms and Machine Parts, (MMP' 86), Brasov. Antonescu, P., M. Oprean and F.I.T. Petrescu, 1987. Dynamic analysis of the cam distribution mechanisms. Proceedings of the 7th National Symposium on Industrial Robots and Space Mechanisms, (RSM' 87), Bucharest. Antonescu, P., M. Oprean and F.I.T. Petrescu, 1988. Analytical synthesis of Kurz profile, rotating the flat cam. Mach, Build. Rev. Antonescu, P., F.I.T. Petrescu and O. Antonescu, 1994. Contributions to the synthesis of the rotating cam mechanism and the tip of the balancing tip. Brasov. Antonescu, P., F.I.T. Petrescu and D. Antonescu, 1997. Geometrical synthesis of the rotary cam and balance tappet mechanism. Bucharest, 3: 23-23. Antonescu, P., F.I.T. Petrescu and O. Antonescu, 2000a. Contributions to the synthesis of the rotary disc-cam profile. Proceedings of the 8th International Conference on the Theory of Machines and Mechanisms, (TMM' 00), Liberec, Czech Republic, pp: 51-56. Antonescu, P., F.I.T. Petrescu and O. Antonescu, 2000b. Synthesis of the rotary cam profile with balance follower. Proceedings of the 8th Symposium on Mechanisms and Mechanical Transmissions, (MMT' 00), Timişoara, pp: 39-44. Antonescu, P., F. Petrescu and O. Antonescu, 2001. Contributions to the synthesis of mechanisms with rotary disc-cam.