RU2304226C2 - Power control method of free-piston internal combustion engine and such free piston internal combustion engine - Google Patents

Abstract

FIELD: automotive industry shipbuilding, mechanical engineering and other industries.

SUBSTANCE: power control of free-piston engine is effected by changing ratio of piston travels at compression and expansion by changing moment of closing of intake valve at corresponding changing of volume of combustion, chamber, and at incomplete power conditions, partial braking of piston during combustion phase is provided by changing gear ratio of power takeoff system. To implement proposed method, free-piston engine is used including cylinder accommodating piston coupled with power takeoff system and intake valve controlled by control system. Design peculiarity is that control system is connected with intake valve and provides change of intake valve closing moment depending of required engine power.

EFFECT: increased efficiency, reduced noise in operation, and heat load on working parts of engine.

9 cl, 2 dwg

Description

The group of inventions falls within the scope of piston internal combustion engines and can be used in the automotive industry, shipbuilding, mechanical engineering and other fields.

A known method of controlling the power of an internal combustion engine, involving, in particular, the principle of operation of free-piston gas generators, the description of which is given in the monograph of Candidate of Technical Sciences P.A. Shelest "Shaftless gas generators" Mashgiz, State Scientific and Technical Publishing House of Engineering Literature, M. 1960.

The disadvantages of the prototype is that the control of engine power occurs only due to the dosing of the masses of fuel and air supplied to the combustion chamber, with a constant ratio of the strokes of compression and expansion. There is no possibility of optimal selection of the engine displacement depending on the required engine power. Under partial power modes, in which the car’s engine runs most of its resource, the engine’s efficiency decreases, and harmful emissions into the atmosphere increase. An engine with this control method in almost all modes has a high exhaust gas temperature and a significant noise level. During the stroke of the piston and, consequently, an increase in volume, the combustion of fuel continues, which is less efficient than combustion at a constant volume.

The device adopted as a prototype was selected from the monograph of Candidate of Technical Sciences P.A. Shelest "Shaftless gas generators" Mashgiz, State Scientific and Technical Publishing House of Engineering Literature, M., 1960.

The disadvantage of the prototype is that it is impossible to adjust the volume of the combustion chamber to control engine power.

The basis of the present invention was the task of developing a method and device for controlling the power of the internal combustion engine in order to ensure high environmental friendliness of the engine by reducing emissions of toxic substances into the atmosphere together with the exhaust gases, which is achieved by improving the combustion processes of the fuel and the maximum possible expansion of the combustion products in the engine cylinder, providing high efficiency. When the engine is operating in partial power modes, there is an increase in efficiency, a decrease in noise, and a decrease in the heat load on the working parts of the engine due to a more complete use of the energy of expanding gases up to a mode when the temperature of the exhaust gases approaches the ambient temperature. To further improve engine performance in partial power modes at the time of the initial phase of fuel combustion, the piston is braked by the control system for the time required for more complete combustion of the fuel in the initial volume.

The specified single technical result in the implementation of the group of inventions on the object - the method is achieved by the fact that the proposed method of controlling engine power, the peculiarity of which is that the operational control is carried out by changing the ratio of the piston strokes during compression and expansion with a corresponding change in the volume of the combustion chamber, and the value the piston stroke during compression is changed due to the moment of closing the intake valve, changes in the amount and type of fuel, and in partial power modes use braking of the piston during the combustion phase by changing the gear ratio of the piston power take-off system.

The specified single technical result in the implementation of the group of inventions on the object-device is achieved by the fact that in an internal combustion engine including a cylinder, a piston located therein, connected to a power take-off system by hydraulic, pneumatic, electric, mechanical or other means, and an intake valve controlled by the control system, the peculiarity is that the intake valve closes at different positions of the piston during the compression stroke, and the position of the piston can be determined by a signal sensor or timer, and the cylinder has outlet windows.

The claimed group of inventions meets the requirement of unity of invention, since the group of diverse inventions forms a single inventive concept, moreover, one of the claimed objects of the group — the internal combustion engine — is designed to implement another claimed object of the group — a method for controlling the power of the internal combustion engine, while all objects of the group of inventions are directed to solve the same problem with a single technical result.

According to the information available to the authors, the set of essential features characterizing the essence of the claimed inventions is not known from the prior art, which allows us to conclude that the inventions meet the criterion of "novelty."

According to the authors, the essence of the claimed inventions does not follow explicitly from the prior art for a specialist, since the above effect on the obtained technical result is not revealed from it - a new property of the object - a set of features that distinguish the claimed inventions from prototypes, which allows us to conclude their compliance with the criterion of "inventive step".

The set of essential features characterizing the essence of the invention, in principle, can be used in an internal combustion engine to obtain a technical result, which consists in changing the ratio of piston strokes during compression and expansion with a corresponding change in the volume of the combustion chamber, and the magnitude of the piston stroke during compression changes due to the moment closing the intake valve, changing the amount and type of fuel, and also due to the braking of the piston during combustion of gases, and the position of the piston can be determined I am on a sensor or timer signal, which allows us to conclude that the inventions meet the criterion of "industrial applicability".

Structurally, such an engine can be designed as a single module, which includes all the devices necessary to ensure its operability, or as a complex of several modules of the same type, combined by a common control system.

Changing the initial (initial) position of the piston in the engine cylinder before the compression stroke allows you to make the engine more economical, that is, reduce fuel consumption by using the full engine power only if necessary.

The control system for the parameters of the working cycle makes it possible to ensure the most complete combustion of fuel and the maximum possible use of the energy of the working fluid.

The proposed method of controlling engine power makes it multi-fuel, since it becomes possible to quickly change the compression ratio.

The control system for the parameters of the operating cycles allows you to quickly change the working volume and stroke length of the piston during compression. The full stroke of the piston during expansion allows maximum use of the energy of the hot working fluid, reducing its pressure and temperature to values close to the external environment, significantly increasing the efficiency in partial power modes.

The invention is illustrated by drawings, where figure 1 shows a method of controlling the power of a free piston engine; figure 2 is a diagram explaining the operation of the device for implementing the method of power control.

The described method for controlling the power of a free piston engine is illustrated by the engine operation diagram shown in FIG.

The stroke of the piston during compression and the removal of energy during the stroke of the piston, as well as the control of the intake valve, can be carried out pneumatically, hydraulic, electric, mechanical and other methods, which are not shown in Fig. 1.

Before starting the engine, the piston 1 (Fig. 1) is in the lower position according to the diagram. Typically, the piston 1 remains in this position after the end of the previous cycle or is installed in it by command of the control system (not shown). The inlet valve 2 opens and the cylinder 3 is filled with a portion of air and / or the cylinder 3 is purged through the channels 4 (Fig. 1a).

Further, the piston begins its upward movement, closing the channels 4. At maximum engine power, the intake valve 2 closes almost immediately (Fig. 1b), so that the amount of air and, accordingly, fuel in the combustion chamber are maximum.

If there is no need for full engine power, then the control system decides to reduce the working volume by changing the compression start point. In this situation, the piston 1 continues to move upward for some time without compressing the air, since the intake valve 2 is not closed (Fig. 1c).

At the moment determined by the control system, depending on the required power, the inlet valve 2 is closed by means of an actuator of pneumatic, hydraulic, electrical, mechanical or other type (not shown) and compression begins (Fig. 1d).

In a diesel engine at a moment close to the maximum air compression (the position of the piston is shown by a dashed line), the injector 5 delivers fuel to the combustion chamber. In a gasoline engine, ignition comes from a spark (not shown). The fuel ignites, the pressure rises, and the combustion products, expanding, change the direction of movement of the piston - the stroke of the piston begins - energy production. At the end of the stroke, the exhaust window 4 opens and the exhaust gases are removed from the cylinder 3 of the engine. Inlet valve 2 opens, purge occurs. The control system using pneumatic, hydraulic, electrical, mechanical or other method, the piston 1 stops in its original, lower position (figure 1), and the cycle repeats.

In the particular case, due to the delay of the piston 1 by the control system in the upper position (shown by a dotted line), it is possible to obtain a combustion chamber with a constant volume for the time required for the most complete combustion of the fuel mixture.

From the description of the principle of engine operation it follows that the engine power control process allows you to have not only an engine of variable displacement with the ability to tune to any fuel, but also with the maximum possible expansion course.

We propose a device for implementing a method of controlling the power of internal combustion engines, consider the example of a free piston internal combustion engine, which is presented in figure 2. The internal combustion engine includes an engine cylinder 1, a piston 2 located therein, a hydraulic cylinder 3 connected to the engine, a hydraulic cylinder 4 piston, an intake valve 5, a nozzle 6, a piston position sensor 7, a control system 8, a reservoir with a working fluid 9, a hydraulic system 10, hydraulic accumulator 11, hydraulic motor 12, outlet windows 13 or valves (option).

The engine operates as follows.

In order for the piston 2 to perform a compression stroke, the working fluid is supplied under pressure from the reservoir 9 to the lower cavity of the hydraulic cylinder 3 from the reservoir 9 through the hydraulic system 10. To increase the efficiency, a pressure transducer (not shown) is installed in the hydraulic system 10. The position of the piston 2 in the cylinder 1 is determined using the sensor 7. Instead of the sensor, you can use the timer, which is built into the control system (not shown). At the moment determined by the control system 8, depending on the required engine power, the intake valve 5 closes.

In the combustion chamber of the cylinder 1 of the engine, the working mixture is compressed. At a moment close to maximum compression, fuel is supplied by the nozzle 6. The fuel ignites and the combustion products, expanding, change the direction of piston 2. In this case, the working fluid under pressure from the lower cavity of the hydraulic cylinder 3 passes through the hydraulic system 10 to the hydraulic accumulator 11. The output velocity of the working fluid (pressure conversion coefficient) from the hydraulic cylinder 3 can be changed by the control system 8 based on the data on the mass of fuel and air in the combustion chamber of the cylinder 1 of the engine, the pressure in the accumulator 11 and the speed of rotation of the shaft of the hydraulic motor 12. At the end of the stroke, Irene piston opens the exhaust ports, and there is a clearing of the cylinder (exhaust). The next cycle can begin immediately after cleaning the cylinder or at the end of a pause determined by the control system, with an incomplete ICE power.

Thus, it is possible to control the movement of the piston according to the law we have chosen, providing the necessary conditions for the complete combustion of fuel at a given working cycle time.

The proposed group of inventions allows to ensure high environmental friendliness of the engine by reducing emissions of toxic substances into the atmosphere together with the exhaust gases, which is achieved by improving the combustion processes of the fuel and the maximum possible expansion of the combustion products in the engine cylinder, providing high efficiency. This allows you to make it multi-fuel, up to the prompt replacement of fuel at different power output, as it becomes possible to quickly change the compression ratio.

When the engine is operating in an incomplete power mode, an increase in efficiency, a decrease in noise, and a decrease in the heat load on the engine working parts are achieved due to a more complete use of the energy of expanding gases up to a mode when the temperature of the exhaust gases is close to the ambient temperature, which makes it possible to reduce the cost of its design by reducing the requirements for materials and the design of some parts.

The application of the described method of controlling engine operating cycles opens up wide possibilities for using the engine in various fields of the automotive industry, mechanical engineering, shipbuilding, and other fields.

Claims (9)

1. A method of controlling the power of a free piston internal combustion engine, characterized in that the operational control of the engine power is carried out by changing the ratio of the piston strokes during compression and expansion by changing the closing moment of the intake valve with a corresponding change in the volume of the combustion chamber. 2. The method according to claim 1, characterized in that when the engine power is incomplete, the piston is braked during the initial phase of combustion. 3. The method according to claim 2, characterized in that the braking of the piston during the initial phase of combustion is carried out by changing the gear ratio of the piston power take-off system. 4. The method according to claim 1, characterized in that depending on the required engine power and / or operating mode, different fuels are used and / or the amount of fuel is changed. 5. A free piston internal combustion engine including a cylinder, a piston located therein, connected to a power take-off system, an intake valve and a control system, characterized in that the control system is connected to the intake valve and has the ability to change the closing timing of the intake valve depending on required engine power. 6. The free piston engine according to claim 5, characterized in that the cylinder has exhaust ports. 7. Free piston engine according to claim 5, characterized in that a piston position sensor is connected to the control system. 8. The free piston engine according to claim 5, characterized in that a timer is installed to determine the position of the piston connected to the control system. 9. The free piston engine according to claim 5, characterized in that the power take-off system is selected from the range: hydraulic, pneumatic, electrical, mechanical.

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