WO2016114683A1

WO2016114683A1 - Internal combustion engine and operating method therefor

Info

Publication number: WO2016114683A1
Application number: PCT/RU2015/000010
Authority: WO
Inventors: Борис Львович ЕГОРОВ
Original assignee: Борис Львович ЕГОРОВ
Priority date: 2015-01-15
Filing date: 2015-01-15
Publication date: 2016-07-21

Abstract

An internal combustion engine operating on the basis of the following theoretical thermodynamic cycle: isothermal compression, isochoric heat supply, isothermal or isobaric expansion, adiabatic expansion, and isobaric or isochoric thermal energy removal. Isochoric heat supply takes place partially using the heat of exhaust gases in a regenerator 6. Isothermal compression takes place in a compressor 8 with the internal cooling of compressed air. The injection of a charge, the injection of fuel and the expansion of a working fluid take place in an engine with opposed cylinders 1 and 2. Communicating pairs of cylinders are axially offset to accommodate valves. The piston of a cylinder with an inlet valve moves with an advance angle towards the piston of a cylinder with an exhaust valve. The inlet of working fluid, the injection of fuel and isochoric combustion take place directly in the cylinders of the engine.

Description

Internal combustion engine and method of operation

Field of Invention

The invention relates to engine

BACKGROUND OF THE INVENTION

Two-and four-stroke spark-ignited gasoline-fueled internal combustion engines operating on the Otto cycle and compression ignition diesel engines operating on the Trinkler-Sabate mixed cycle are known and widely used. Over the past decades, significant progress has been made in increasing the fuel efficiency of these engines, but mainly in variable operating modes. Increasing the maximum effective efficiency is complicated by the limited theoretical efficiency of thermodynamic cycles used in ICEs and the complexity of the practical implementation of the known methods for increasing it. So, for example, the method of increasing efficiency by increasing the compression ratio is limited by the strength of structural materials and adverse side effects, such as, for example, detonation in gasoline engines, an increase in mechanical losses, and a number of others. The method of continued expansion, as in the Miller and Atkinson cycles, is associated with a decrease in liter capacity, an increase in mechanical and pump losses. The use of boost also has certain limitations, which do not allow further significantly increase the maximum

effective engine efficiency.

To further significantly increase the efficiency of internal combustion engines, it is necessary to apply a more efficient thermodynamic cycle with the possibility of using low-potential thermal energy released by the engine during operation. The proposed thermodynamic cycle is closest to the cycle, described in the application JV ° PCT RU2014 / 000720 for two-stroke internal combustion engines with isothermal compression and a separate combustion chamber. But the difference of the proposed cycle is the use of heat recovery of exhaust gases, that is, it is a regenerative isothermal cycle, which significantly increases its efficiency. The implementation of the cycle is proposed to be implemented in an engine with an opposed arrangement of communicating pairs of cylinders and counter-movement of the pistons. Unlike traditional engines with this arrangement, the proposed engine cylinders are located with axial displacement for

the possibility of placing poppet valves, and the movement of the opposing pistons is carried out not synchronously, but with a certain advance angle to allow the intake and isochoric supply of thermal energy directly in the engine cylinders. This design allows you to abandon a separate combustion chamber and realize direct fuel injection, which significantly reduces thermal and gas-dynamic losses.

SUMMARY OF THE INVENTION

The main goal of the proposed method is to increase engine efficiency

internal combustion through the use of a more efficient thermodynamic cycle and its implementation in a device whose design allows to minimize thermal, mechanical and gas-dynamic losses.

The following cycle was taken as the basic theoretical thermodynamic cycle (Fig. 1, 2): isothermal compression - isochoric heat supply - isothermal (isobaric) expansion - adiabatic expansion - isobaric (isochoric) heat removal. This cycle, like the Stirling or Ericsson cycle, is also regenerative, or rather partially regenerative. The heat of the exhaust gases is used to heat the working fluid to a temperature of self-ignition after isothermal compression before being allowed into the engine cylinders. To determine the theoretical thermal efficiency of a given cycle,

must be compared with the ideal Carnot cycle in the heat diagram.

As shown in FIG. 3, the lower part of the cycle diagram (under the dashed line) is similar to the ideal Stirling cycle. As is known, an ideal Stirling cycle has the same efficiency as an ideal Carnot cycle, i.e. the maximum possible for a given temperature difference. Thus, provided that the heat recovered during the release process is perfectly regenerated, there will be no increase in entropy, and hence no heat loss, in the bottom of the diagram of the proposed cycle.

In the upper part of the cycle diagram (above the dashed line), the proposed cycle will not be regenerative and it is more convenient to compare it directly with the Carnot cycle. As follows from the diagram, in contrast to the Carnot cycle in the proposed cycle

isochoric heat input is used instead of heating the working fluid as a result of adiabatic compression (isoentropic compression). Theoretically, isentropic compression is more effective, since entropy does not increase as a result of it, and, therefore, in this case, the efficiency of the entire proposed cycle would be similar to the efficiency of an ideal Carnot cycle for a given temperature difference. But in real conditions, the use of adiabatic compression in this case will be difficult and less practical due to the significant complexity of the design, increased compression work, mechanical and heat losses, and

reduction in liter capacity.

Thus, the theoretical efficiency of the proposed cycle will be as close as possible to the efficiency of the ideal Carnot cycle, and differ only in the amount of losses due to increased entropy during isochoric heat supply, graphically depicted in the diagram as a triangle formed by the isochoric heat supply line and two dashed lines of the imaginary cycle Carnot (Fig. 3).

Under real conditions, isothermal and adiabatic expansion can be replaced, by analogy with the real Otto cycle, with polytropic expansion, or by analogy with the real Sabate-Trinkler cycle, with isobaric and polytropic

expansion. The proposed cycle allows you to completely replace the adiabatic compression used in all traditional ICEs with isothermal compression, which is carried out in a separate compressor with high mechanical efficiency (about 0.98) and efficient internal cooling, for example, in a screw compressor with oil or water (coolant) injection and polytropic compression close to 1.1. As you know, the efficiency of industrial screw compressors with oil injection and

isothermal compression up to 30% higher than the efficiency of reciprocating compressors. Effective implementation of the cycle is possible with a degree of pressure increase in the process of isothermal compression from 20 and above. The temperature at the end of isothermal compression in a screw compressor is about 100 ° C or slightly higher. If it is not possible to compress to a given pressure in a single-stage compressor, a two-stage screw compressor or a single-stage screw compressor with an additional supercharger of any suitable design with or without an intercooler can be used.

In the proposed regenerative cycle, after isothermal air compression and separation, the fresh charge is heated with exhaust gases in a heat exchanger

(regenerator) increasing the temperature to 500-600 ° С and reaching the temperature

auto-ignition fuel. To facilitate a cold start, the regenerator can be heated by an additional device operating on the principle of a pre-heater, and the engine itself is equipped with a glow plug similar to diesel engines.

After heating with exhaust gases, the working fluid is injected directly into the engine cylinders under a pressure of 25 atm. and higher. The intake period should be approximately 15-20 ° of crankshaft rotation. At the same time, they ensure optimal filling, including at high speeds, by correctly selecting the cross section of the intake valve (s).

In the proposed engine, the communicating opposed cylinders are located with axial displacement for the possibility of placing poppet valves, and the opposing pistons counter-move not synchronously, but with a certain advance angle to allow the intake and isochoric supply of thermal energy directly inside the cylinders (Fig. 4, 5, 6 ) When the piston of cylinder 1 (Fig. 4) reaches TDC and the piston of cylinder 2 is approximately 25-35 ° to TDC, the working fluid is inlet through the inlet valve (s) of cylinder 1. The inlet lasts about 15-20 ° of crankshaft rotation.

Simultaneously with the inlet of the working fluid, fuel injection can also be started. As in a diesel engine, the start of injection is carried out with a certain advance angle or even delay, depending on the speed of the crankshaft. So at the maximum speed, the injection can be started simultaneously with the intake of the working fluid or even before it. But the ignition delay phase must end after closing the intake valve or at the same time as it closes. High inlet pressure and flow of the working fluid from cylinder 1 to cylinder 2 and vice versa will provide maximum charge turbulence for high-quality mixing with the injected fuel and more efficient and complete combustion.

In general, fuel injection and combustion processes can be organized

similar to direct injection diesel engines. After closing the intake valve, when the piston of cylinder 2 is 5–10 ° before TDC, the phase of active combustion of the fuel begins and the pressure in the cylinders rises sharply. The pistons of the opposing cylinders will move in the same direction for a certain time, forming a constant volume combustion chamber. In this case, the forces acting on the pistons will be theoretically mutually balanced with the same diameter of the pistons.

At the inlet of the working fluid, when the piston of cylinder 1 will be at TDC, the jet of a compressed working fluid under high pressure will first act on the piston of cylinder 1 aimed at doing useful work and the pressure in cylinder 1 will increase faster. Thus, upon the inlet of the working fluid, useful work will also be performed, compensating to a certain extent for losses during the flow of the working fluid into the cylinders. It is also preferred that the ignition of the fuel starts in cylinder 1, which is more likely based on

engine design and mode of operation. When the piston of cylinder 2 reaches TDC, both pistons will be directed to perform useful work and the expansion phase of the working fluid will begin (Fig. 5). In contrast to the traditional ICE, in which the active phase of fuel combustion also begins before the piston reaches TDC and therefore an additional negative work of compression is performed, there will be no such negative work in the proposed design. Until the TDC reaches the piston of cylinder 2, the forces acting on the pistons will balance each other, and after the TDC, both pistons will perform a positive useful expansion work.

At the beginning of expansion, the piston of cylinder 1 will already be 25-35 ° after TDC, which is also more effective from the point of view of mechanics than the effect of maximum pressure on the piston in TDC.

When the piston of the cylinder 1 reaches the BDC, open the exhaust valve (s) located on the cylinder 2 and release the spent working fluid through the regenerator into the atmosphere (Fig. 6, 7). In this case, the regenerator can also perform the functions of a catalytic converter when coating its surfaces,

contacting with exhaust gases with special substances. The exhaust valve is closed before opening the intake valve.

Figure 11 shows a comparative theoretical thermal calculation of the proposed cycle and the Sabate-Trinkler cycle for a turbocharged diesel engine with a compression ratio of 18.5. In the comparative calculation, the same values of the expansion polytropic and heat capacities, close to those of real diesel engines, are taken for clarity. As can be seen from the calculation, the thermal efficiency of the proposed cycle significantly exceeds the thermal efficiency of the Sabate-Trinkler cycle and can reach 0.78, which does not contradict the theory, since the efficiency of the ideal Carnot cycle for a given temperature difference (293K and 2457K) will be approximately 10% higher .

The mode of the proposed engine is push-pull and without compression in the expansion cylinders; therefore, much less cylinder volume is needed for the same power than for a diesel engine. According to calculations, the liter capacity of the proposed engine will be approximately 2 times greater than the diesel engine. The mechanical efficiency of a screw compressor can be 0.98, and the mechanical The adiabatic compression efficiency in ICE cylinders is at best 0.9. The compression work in the proposed engine will be approximately 3 times less than in a diesel engine with the same power. The maximum pressure in the cylinders of the proposed engine is approximately 2 times lower than in the cylinders of a diesel engine. From all this it follows that the mechanical efficiency of the proposed engine will be significantly higher than the mechanical efficiency of the diesel engine.

The area of metal surfaces in contact with the working fluid during fuel combustion and at the beginning of expansion will be even smaller than in a diesel engine with direct injection, therefore, the relative efficiency

the proposed engine will also be higher.

Based on the foregoing, it can be assumed that the effective efficiency of the proposed engine can reach 60%.

DESCRIPTION OF DRAWINGS FIG. 1 TS diagram (temperature-entropy) of the proposed theoretical cycle.

FIG. 2 PV diagram (pressure-volume) of the proposed theoretical cycle.

FIG. 3 Comparative TS diagram of the proposed cycle and the ideal Carnot cycle.

FIG. 4, 5, 6 Schematic representation of engine operation during inlet, expansion, and exhaust. FIG. 7 General diagram of a device operating according to the proposed method.

FIG. 8 Scheme of the expansion machine of the proposed device.

FIG. 9 Variant of inlet valve with hydraulic actuator.

FIG. 10 Diagram of the hydraulic drive of the intake valve.

FIG. 11 Comparative calculation of the engine working on the proposed cycle and the diesel engine working on the Sabate-Trinkler cycle. Description of an embodiment of the invention

The implementation of this method of operation can be carried out in a device, a diagram of which is shown in FIG. 7. The device contains the following main elements: expansion cylinders 1 and 2, inlet valve 3, exhaust valve 4, nozzle 5, regenerator 6, separator 7, compressor 8, fan 9, compressor cooling radiator 10, fuel tank 11, high pressure fuel pump 12.

The design of the device may consist mainly of well-known technical solutions. A screw compressor with oil or water injection, equipped with a cooling system and separation of the injected liquid can be standard or with a lightweight housing. The regenerator, which is a heat exchanger, can be supplemented by a pre-heating system and a system of neutralizing harmful substances. The engine power system is generally similar to direct injection diesel systems. The expansion machine or the engine itself actually consists of two opposed blocks of the known

lower valve design with side valves (Fig. 8, 10). The inlet valve must be of a special design that prevents spontaneous opening due to the pressure difference, and also be as balanced as possible so that it does not require large energy costs to open it. An embodiment of the valve is shown in FIG. 9. Since the valve's opening phase is approximately 15-20 °, the implementation of its mechanical drive can cause difficulties. In FIG. Figures 9 and 10 show an inlet valve with a hydraulic actuator. The cam of the hydraulic drive is located on the flywheel or behind the flywheel (Fig. 10). The exhaust valve has an almost standard design of a side poppet valve with a lower camshaft (Fig. 8).

Claims

Claim

An internal combustion engine, characterized in that the theoretical thermodynamic cycle of the engine includes isothermal compression, isochoric supply of thermal energy, isothermal or isobaric expansion,

adiabatic expansion, isobaric or isochoric heat energy removal, wherein the isochoric heat energy supply is partially performed in

a heat exchanger-regenerator using the heat of the exhaust gases, the heat is removed both in the exhaust process and in the process

isothermal compression, performed in a separate refrigerated compressor, and the main supply of thermal energy and expansion of the working fluid is carried out in an expansion machine consisting of a pair or pairs of communicating opposed cylinders located with axial displacement to accommodate the intake and exhaust valves, while the cylinder piston has an intake valve moves towards the opposite piston of the cylinder with an exhaust valve with a certain advance angle, forming a chamber c with the opposite piston for a given time a constant volume scream that allows

carry out the inlet of the working fluid, direct fuel injection and isochoric combustion in the engine cylinders.