Piston Engines of the New Generation (Without turbo – supercharging). Anatoly Matveevich Druzhinin
engines but also for KAMAZ, YaMZ and other engines was used by the world famous German company Goetze, which is under the patronage of the equally famous Federal Mogul concern – “the advanced European manufacturer of the engine gaskets and piston rings”. That is, all claims to poor-quality piston engine compaction should be presented not to the main designers of these engines, but to world-famous specialists with whom the “main” are in solidarity.
To this we must add the following circumstance. From the advertisement of its latest achievement, the manufacturer of the elements of CPG the Kostroma-Motordetal presented “ncMDChr (nanochrome) – a new generation coating is applied to the working surface of the upper compression and oil-removable piston rings”! Especially shocking “… and oil-removable rings”, inefficient, performing a rough operation of removing oil from the cylinder wall, in a continuous oil environment.
It is unclear why to apply “nanochrome” on them, if the working surface of the oil-removable piston ring does not wear out and without “nano”. When it is necessary to change the piston rings, along with the compression rings, oil-removable rings also fall into disassembly, but not because they have a “worn working surface”, but because the waste oil is clogged, sometimes coked, by the spiral extension of the oil-removal ring. This is especially true of the diesel engines. The inefficient oil-removal piston ring becomes generally inoperable.
This is an example of the imperfection of the widely used oil-removable ring with useless “nanochrome”. Nevertheless, Kostroma is pleased, scientific and technological progress all that is needed for the buyer to “appreciate” these innovations.
The design of compression piston rings, subjected to rigid analysis by the author, continue to “live” and “improve.” The achieved results of the research and the proposed measures for the recognized authorities of the car industry are not so “obvious”, there may be other reasons that have nothing to do with science.
The low efficiency of consolidation between the piston and cylinder is one of the most important problems of the ICE. The negative consequences of this decision are obvious, the engine can “earn” and operate normally only at huge speeds of rotation of the crankshaft, boosting the engine work. What leads to “forcing” should be known even to the motorist.
The problem of gaps is only part of the general problem of the “cylinder-piston ring-piston” system. In this case, on a working step “admission”, in the absence of excessive pressure over the piston, the mechanical friction losses of the compression rings affecting the efficiency of the engine or compressor The magnitude of the mechanical losses at the “admission” step depends on the magnitude of the elastic forces of the piston seal ring and the friction coefficient of the two kinematic elements: “Piston ring-cylinder”, more specifically, the working surface of the piston ring and the cylinder wall.
The shape and dimensions of the piston seal ring at the “admission” step depend mainly on the design value of the minimum necessary elastic force of the ring. It is necessary to determine the magnitude of the elastic force of the piston ring and the necessary material from which the ring should be made.
In analysis of the reasons for the low efficiency of internal combustion engines, it was found that in calculating the sizes and permissible deviations in the manufacturing process, in domestic engines, especially in the cylinder-piston group, there is lacks precision; therefore, as one of the measures to increase the efficiency of internal combustion engines, in the system “cylinder – piston ring – piston “was held minimization of gaps [10].
The modern piston rings, depending on their size, are mainly made of steel and cast iron. The researches, the developed theory of designing of the piston rings provide an opportunity of manufacturing of rings from other metals and alloys, and also nonmetallic materials. For example, the domestic company LLC “Compressor Technologies” advertises bronze with various fillers, various plastics as a material for manufacturing sealing and oil-removable piston rings.
At the research stage, to define the shape and dimensions of the sealing (compression) piston rings, using the results of theoretical studies, to recommend various bronze alloys and copper alloys as a material for the preparation of the ring.
– Working step “compression” of a fresh charge of air, fuel-air mix and its ignition
The working step “compression” is fundamentally different from the previous step “admission” in that by obtaining a piston ring pressed against the upper flange of the piston groove and to the wall of the cylinder by the force of its own elasticity, at the beginning of the piston’s movement to the upper position, the piston ring is shifted downward. The forces of friction of the piston ring working surface against the cylinder wall, as well as the appearing overpressure P0 above the piston and in the piston groove, further enhance the contact of the piston ring with the lower flange of the piston groove and the cylinder wall.
It is important to note, the piston ring being in the lower dead point in rather free state, is fixed in this position, appearing changes and, above all, increasing pressure over the piston. This position of the sealing piston ring relative to the piston and cylinder will remain unchanged on the remaining steps of the engine motoring run.
So, with the beginning of the piston’s movement to the upper position on the working step “compression”, gas dynamics comes into operation, according to the scheme given above to fig. 1. On a working step “admission” the design of a piston sealing ring, its shape and dimensions, weren’t of particular importance, solving the main task of effectively consolidation of the free space between the piston and the cylinder with the minimum possible mechanical friction losses.
At this stage, the developer must solve the problem of the correct use of gas-dynamic forces that will preserve the elastic forces of the piston ring, thereby guaranteeing its working capacity [11].
The author to solve this problem developed a formula, the use of which in the calculation of the geometric characteristics of a sealing piston ring allows neutralizing the negative effect of huge gas-dynamic forces on the operation of the piston ring. This formula solved the historical injustice of the subjective decision in assigning the height of the piston ring, although this decision was made by an authoritative German scientist [5].
It was suggested to “choose” for the engine the free size of the height of the sealing piston ring in an unreasonable range of sizes, relying only on the recommendation of an authoritative scientist: “Usually, the ratio of h/a shouldn’t be lower than 0,5 – 0,45” (h – height of a piston ring, and – the radial thickness of a ring).
The domestic scientists and then developers of the piston cars took these recommendations for an axiom which, obviously, those far sixtieth years of last century, didn’t demand any proofs, pilot and other studies which had to be carried out at so basic decision. As a result, instead of an incomprehensible range of sizes of “recommendations” for the height of the piston ring, there appeared “precise” indications of the domestic standards. Designers did not have to calculate the height of the sealing ring, thereby removing all responsibility for low-quality products from all “general” and “main” ones.
For example, the current GOST 621—87 for cylinder diameters of 88 mm and 130 mm “determined” the height of the sealing rings for both 2.0 mm. It’s incomprehensible! Really when developing so responsible document how the technical standard, it was unclear that from the given size of diameter of the cylinder equal to the outer diameter of a piston ring, all other geometrical characteristics of a ring depend?
How can ignore the enormous working pressures in the engine cylinders, reaching 20 MPa (200 kg / cm2) and actively affecting to the free surfaces of the movable piston ring? In these extreme conditions, the minimum change in the height of the sealing ring and its radial