RU2432474C2 - Reciprocating internal combustion engine operation method - Google Patents

Abstract

FIELD: engines and pumps.

SUBSTANCE: staged air compression is performed with simultaneous decrease (discharge) of its temperature and staged extension of working gases by means of additional fuel injection. The heat from exhaust gases is used for compressed air heating. Staged air compression and staged extension of working gases brings engine strokes performance close to isothermal process and thus results in performance coefficient increase and fuel consumption decrease.

EFFECT: increase of engine performance coefficient by means of: decrease of compressed air operation, increase of working gases extension operation, application of non-piston-rod converter of piston reciprocating movements into output shaft rotation and regeneration of exhaust gases heat.

7 cl, 3 dwg

Description

The invention relates to mechanical engineering, in particular to engine building, and can be used in the development of engines for various vehicles and stationary installations.

A known method of operating the engine according to patent RU No. 2022136, according to which, during expansion in the working cylinder of the combustion products, air is re-fed into the compressor cylinder, which is sent to the working cylinder during exhaust gas discharge. In this case, fuel is injected in two portions, the second portion being fed after reaching the maximum proportion of the first portion and before the end of its injection. Additional fuel supply to the working cylinder leads to an increase in gas temperature, which leads to an increase in the expansion work. In addition, it is very difficult to position the time of supply of the second portion of fuel, which, instead of increasing the expansion time of the working fluid, can only cause a temporary surge in the combustion temperature of the fuel mixture, which will not provide an increase in the expansion work — the mechanical operation of the engine.

Due to the absence of a process for cooling air during its compression, a stepwise (portioned) fuel supply does not give a positive effect. And the heating of gases during their expansion due to mixing with exhaust, without the use of regenerators, also raises great doubts.

Therefore, the additional air supply to the working cylinder through the compressor and repeated injection of fuel for its combustion, in addition to increasing the consumption of the fuel mixture, does not give anything.

However, this method is taken as a prototype of the developed method of engine operation.

The technical result of the developed method is as follows. The operation of a reciprocating internal combustion engine is carried out by performing the cycle cycles of the engine in the compressor and working cylinders, compressing the air in the compressor, injecting fuel into the working cylinder with subsequent combustion, expanding the combustion products - the piston stroke and exhaust gas, while compressing the air in the compressor the cylinder is produced in steps, with two or more steps, with intermediate cooling of the air and its supply to the receiver and regenerator through the working cylinder, and the gas expansion process It is performed stepwise, with two or more stages, with an intermediate additional fuel injection and supply of heat taken from the exhaust gases to the air sent to the working cylinder, while the four-cycle engine operation cycle is carried out separately - the intake and compression cycles of the air in a separate compressor, and the cycles - the working stroke and exhaust exhaust is directly in the working cylinder, and the working cylinder can work in a double working mode, thereby ensuring the execution of two working cycles in one n rotation of the output shaft, the preparation of the fuel mixture is carried out in the pre-chamber by supplying compressed and heated air in the regenerator from the receiver and injecting fuel when the piston reaches top dead center after the end of the exhaust gas process. As a result, the four-stroke engine operates in two cylinders: the compressor cycle — air intake and compression cycles, and the working cycle — gas expansion and exhaust exhaust cycles.

In this case, air compression is performed stepwise with intermediate cooling at each stage and with subsequent supply to the receiver. Stepwise compression of air with cooling brings the process closer to isothermal, which minimizes the compression work.

And the process of gas expansion - the piston stroke - is also carried out stepwise, while at each stage, fuel is additionally injected into the combustion chamber, which brings the process closer to isothermal and leads to an increase in the work of gas expansion and, thus, mechanical work on the engine output shaft.

In addition, before applying compressed air to the working cylinder, it is heated by the heat of exhaust gases in a heat exchanger (regenerator).

As a result, the implementation of the proposed method of operation of the engine are implemented:

- reduced work on receiving compressed air;

- increase the work of expanding the working gases;

- lower fuel consumption due to heat recovery of exhaust gases.

The described method of organizing engine operation leads to a cycle consisting of two isotherms (air compression and gas expansion) and two isochores (gas cooling and air heating in the regenerator). Such a cycle is known to be a generalized Carnot thermodynamic cycle, the efficiency of which in a given temperature range is equal to the efficiency of the classical Carnot cycle, consisting of two isotherms and two adiabats.

The engine according to the proposed method operates on a four-cycle cycle.

Figure 1 cycle of the internal combustion engine with isothermal compression and expansion and regeneration of heat, schematically shows all the stages of the processes of isothermal compression and expansion of the working fluid, as well as the regeneration of heat of exhaust gases.

The numbering of processes in figure 1 denotes

- Line 0-1 represents the line for drawing air from the atmosphere into the cylinder of the first compressor stage.

- Line 1-2 represents polytropic air compression in the first compressor stage.

- Line 2-a represents the process of forcing air into the intercooler.

- Line a-3 is the line for sucking air into the second stage of the compressor.

. Как видно из диаграммы, в процессе охлаждения сжатого воздуха происходит уменьшение его объема на величину ΔV₁=V₂-V₃, причем без изменения его весового количества.- Line 2-3 represents the process of isobaric air cooling in an intercooler with the transfer of heat to the environment in the amount of

. As can be seen from the diagram, in the process of cooling compressed air, its volume decreases by ΔV ₁ = V ₂ -V ₃ , and without changing its weight quantity.

- Lines 3-4, 4-b, b-5 - respectively, represent polytropic air compression in the second stage of the compressor, forcing air into the intercooler and sucking air into the third compressor cylinder.

. При этом объем газа уменьшается на величину ΔV₂=V₄-V₅.- Line 4-5 represents the process of isobaric air cooling in an intercooler with the transfer of heat to the environment in the amount of

. In this case, the gas volume decreases by ΔV ₂ = V ₄ -V ₅ .

- Line 5-6 is a process of polytropic air compression in the third stage of the compressor.

- Line 6-c represents the discharge of air into the container (receiver).

- The s-6 line is a line for absorbing air into a regenerative heater (heat exchanger).

- In the process 6-7, heat transfer q _reg from the exhaust gases to the air in the regenerative heater (heat exchanger) takes place.

- With parameters at point 7 (P ₇ and T ₇ ), the air is in the combustion chamber.

- In the process 7-8, fuel is injected through the nozzle into the combustion chamber and ignited, as a result of which heat q _{1 is} supplied to the working fluid. At point 8, the gas is located at the maximum parameters (P ₈ , T ₈ ).

After ignition of the fuel as a result of increasing gas pressure, the nozzle valve opens and the piston begins to make the first part of the stroke.

In figures 1 and 2, this process is depicted by line 8-9 and is an adiabatic expansion of the working fluid.

путем подачи в камеру сгорания дополнительной порции топлива через форсунку. В процессе 10-11 происходит дальнейшее адиабатное расширение газа. В процессе 11-12 к рабочему телу впрыскивается еще одна дополнительная порция топлива. В результате чего при его сгорании к рабочему телу подводится дополнительная теплота в количестве

.In the isobaric process 9-10, heat is additionally supplied to the working fluid in an amount

by supplying an additional portion of fuel to the combustion chamber through the nozzle. In the process 10-11, further adiabatic expansion of the gas occurs. In the process 11-12, another additional portion of fuel is injected to the working fluid. As a result, during its combustion, additional heat is supplied to the working fluid in the amount of

.

и

должны быть такими, чтобы температура в точках 10 и 12 была равна температуре в точке 8. В результате такого ступенчатого (или непрерывного) процесса подачи топлива процесс расширения газа в цилиндре в целом будет приближаться к изотермическому, при котором, как известно, вся теплота, подводимая к рабочему телу, превращается в работу.Values of heat input

and

must be such that the temperature at points 10 and 12 is equal to the temperature at point 8. As a result of such a stepwise (or continuous) process of fuel supply, the process of expansion of the gas in the cylinder as a whole will approach isothermal, in which, as you know, all the heat brought to the working fluid, turns into work.

In process 12-13, adiabatic expansion of the gas occurs at the final stage of the piston movement from top dead center to bottom. In the isochoric process 13-14 in the regenerator (heat exchanger), the heat q q is _removed from the exhaust gases to the air supplied to the combustion chamber. In this case, the temperature and gas pressure decrease from the parameters at point 13 to the parameters at point 14, and the air temperature and pressure after the regenerator (heat exchanger) increase from the parameters at point 6 to the parameters at point 7. In process 14-1, the exhaust gases cool down atmosphere with the transfer of heat to the environment in the amount of q _2.

With appropriate selection of the surfaces of the heat exchangers, the air temperature at points 3 and 5 will be equal to the temperature at point 1, which ensures that the air compression process as a whole is performed at a temperature close to the isothermal process.

It is known that the isothermal compression process in terms of the amount of work spent on this is the most profitable in comparison with other compression processes.

As a result, when organizing all activities related to multi-stage compression and multi-stage expansion (combustion) under the condition of heat transfer (process 13-14) to air (process 6-7) in regenerative heaters, the cycle under consideration will be as close as possible to the generalized Carnot thermodynamic cycle ( see figure 3). Such a cycle, as is known, consists of two isotherms and two equidistant curves (isochore or isobar, in our case, isochore).

Its most important advantage is its high efficiency, which in the same temperature range (for example, T ₁ and T ₈ ;) is equal to the efficiency of the usual Carnot cycle, consisting of two isotherms and two adiabats.

The generalized Carnot thermodynamic cycle, consisting of two isotherms and two isochores, is shown in Fig.3. The efficiency of the generalized Carnot cycle is determined by the formula

.

.

If we take the temperature in the combustion chamber equal to 1000 ° C, and the ambient temperature 0 ° c, then

.

.

If we take into account that the best modern engines have an efficiency of not more than 35-38%, then we can conclude that they use less than half the working capacity of the heat used, i.e. more than half of the heat generated in such engines is released into the environment. Therefore, to increase the efficiency of modern engines there are significant reserves. From the cycles shown in FIGS. 1, 2 and 3, it can be seen that it is possible to create more efficient internal combustion engines. The proposed method of increasing the efficiency of internal combustion engines fully confirms this.

Claims (7)

1. The method of operation of a piston internal combustion engine (ICE) by performing the cycles of the engine in the compressor and working cylinders, compressing air in them, additional air compression in the working cylinder, injecting fuel into it with subsequent combustion, expanding the combustion products - piston stroke and exhaust gas, characterized in that the compression of air in the compressor cylinder is performed stepwise, with two or more steps, with intermediate cooling of the air and supplying it through the receiver to the working cylinder, the gas expansion process is carried out stepwise, with two or more steps, with an intermediate additional fuel injection and the supply of heat taken from the exhaust gases to the air sent to the working cylinder. 2. The method according to claim 1, characterized in that the stepwise compression of the air is carried out in a separate multistage compressor with intermediate air cooling. 3. The method according to claim 1, characterized in that the air compressed in the compressor is heated in the regenerator by the heat of exhaust gases before being fed into the combustion chamber. 4. The method according to claim 1, characterized in that the stepwise expansion of the gas is accompanied by an additional injection of fuel in order to bring the process closer to isothermal. 5. The method according to claim 1, characterized in that the four-cycle cycle of the engine is performed separately — the suction and compression strokes of the air in a separate compressor outside the working cylinder, and the clocks — the working stroke and exhaust gas exhaust — directly in the working cylinder. 6. The method according to claim 1, characterized in that the working cylinder can operate in dual working modes, which provides them with the implementation of two working cycles for one revolution of the output shaft. 7. The method according to claim 1, characterized in that the fuel mixture is prepared in the pre-chamber by supplying compressed and heated air in the regenerator from the receiver and injecting fuel when the piston reaches top dead center after the end of the exhaust gas process.

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