RU2450137C1 - Piston engine with external combustion chamber fed from free-piston gas generator - Google Patents

Abstract

FIELD: engines and pumps.

SUBSTANCE: combustion product pressure in combustion chamber approximates to operating threshold to open flap 13 to allow combustion products to flow to engine gas distribution valves. Control system follows the piston position in cylinders to open gas distribution valve of the cylinder wherein piston stays between TDC and BDC. Combustion products forced into cylinder act on piston to drive it and convert piston kinetic energy into p.t.o.-shaft rotation. With piston reacting TDC, control system changes gas distribution valve over from position allowing combustion product flow from combustion chamber into cylinder into that whereat exhaust gases are forced out into atmosphere.

EFFECT: higher efficiency of conversion of expanding gases.

1 dwg

Description

Technical field

The invention relates to power engineering.

State of the art

The closest analogues of the claimed invention are patents RU 2324060 C1 “Free-piston gas generator of a ram engine with two compressor drive pistons” and RU 2324830 C1 “Free-piston gas generator of a ram engine with one piston of compressor drive”.

The principle of operation of both gas generators is largely similar. Therefore, it is enough to consider the principle of operation of one of them, namely the “Free-piston gas generator of a ram engine with two compressor pistons”.

When starting the gas generator with an external combustion chamber (hereinafter referred to as the gas generator), fuel is supplied to the combustion chamber 1 (see drawing) by the nozzle 2 and ignited by the spark plug 3. Combustion products through the gas distribution valve (hereinafter referred to as patent valve RU No. 2349765 C1, “ Pneumatic valve actuator of a single-stroke free-piston engine with an external combustion chamber ”) 4 enters the left cavity of the compressor drive piston 5, as a result of which the piston 5 and the piston of the compressor 7 connected to it by the piston rod 6 move (as shown) from left to right. Since the area of the left (according to the figure) surface of the piston 5 is larger than the area of its opposite surface by the cross-sectional area of the rod 6, the air pressure in the cavity to the right of the piston 5 (compressor cavity) is greater than the pressure of the combustion products to the left of the piston 5. Therefore, the air from the right piston cavity 5 (compressor cavity, the valve 8 is closed) through the valve 9 enters the combustion chamber 1, thereby providing air to the fuel combustion process. At the same time, when the piston 7 moves, air (from the following combustion products) from its right cavity through the valve 10 (valve 11 is closed) is released into the atmosphere, and through the open valve 12, air from the atmosphere is sucked into the left piston cavity 7. When the pistons reach 5 and 7 of the rightmost position, a control system (not shown) translates valves 4 and 10 to opposite positions. Now, the combustion products from the combustion chamber enter the right cavity of the piston 7, and the pistons 5 and 7 move to the left. Air from the left cavity of the piston 7 opens the valve 11 and enters the combustion chamber 1. The valve 9 closes and air from the atmosphere through the opened valve 8 is sucked into the right cavity of the piston 5. As soon as the pressure of the combustion products in the combustion chamber reaches the operating value, the shutter 13 and combustion products enter the expansion machine.

From the description of the principle of operation of the gas generator, it is seen that the combustion products from the chamber enter its cylinders during the movement of the pistons from one extreme point to another, while the temperature and pressure of the combustion products entering the cylinders practically do not differ from their pressure in the combustion chamber. The main expansion of the combustion products occurs in the exhaust valve when they are released in the period from opening to closing the exhaust valves 4 or 10. However, their energy does not do any useful work. For efficient energy conversion of expanding combustion products, it is necessary to organize their expansion directly in the cylinder of the expansion machine of the gas generator - application No. 2011919000 "Optimization of the expansion process of the combustion products of a free-piston gas generator with an external combustion chamber", arrival date 05/11/2010, incoming No. 026958. By analogy with the internal combustion engine, the cylinder of the gas generator can be divided into two volumes. The first, smaller, corresponds to the combustion chamber of the internal combustion engine - a virtual combustion chamber. Depending on the direction of movement of the piston group, it is alternately located with one or the other cylinder head. The remaining volume of the cylinder, in fact, as in the internal combustion engine, is the virtual working volume. At the beginning of the working cycle, when the piston group is at the starting point of movement (for example, in the figure on the left), the control system opens the intake valve 4 and the combustion products from the combustion chamber enter the virtual combustion chamber of the cylinder, the temperature and pressure of which are almost equal to those in the chamber combustion 1. Pistons start moving from left to right and, when they pass the virtual combustion chamber, the control system closes the intake valve 4, stopping the access of combustion products to the cylinder. From this moment, the actual process of expansion of combustion products begins. The timing of the opening and closing of the gas control valve — the duration of the inlet of the combustion products into the cylinder — the control system determines, taking into account the temperature and pressure of the combustion products, in such a way as to ensure maximum efficiency of the process of their expansion in the virtual working volume of the cylinder. Thus, the working cycle from a thermodynamic point of view is similar to that in a diesel engine. The difference is that the stroke length of the piston group in the cylinder does not depend on the design of the crank mechanism, which is simply not in the power module, and is determined by the control system based on the requirement to ensure optimal expansion of the combustion products and noiselessness in accordance with the physicochemical characteristics of the used currently fuel.

SUMMARY OF THE INVENTION

A piston engine powered by a working fluid generated by a free-piston gas generator operates as follows. As soon as the pressure of the combustion products in the combustion chamber of the generator reaches the operating value, the control system opens the shutter 13 and the combustion products enter the engine gas distribution valves. The control system monitors the position of the pistons in the cylinders and opens the gas control valve of the cylinder in which the piston is between the start and end extreme points of movement. The combustion products entering the cylinder act on the piston and it begins to move. The energy of a moving piston by a motion conversion mechanism (for machines with cylindrical pistons, a crank mechanism, for machines with rotary pistons a crank) is converted into rotational energy of the power take-off shaft. Upon arrival of the piston at the extreme end point of movement, the control system closes the intake valve and opens the exhaust valve. By the transmission mechanism, the piston returns to the starting point of movement, pushing the products out of the cylinder.

Disclosure of invention

A piston engine powered by a working fluid from a free-piston gas generator with an external combustion chamber that converts exothermic energy of motor fuel into mechanical energy of power take-off rotation includes a free-piston generator with an external combustion chamber, a piston expansion machine with inlet and outlet valves with an electro-pneumatic drive, and a control system, characterized in that to ensure the operation of the engine expansion machine, the control system monitors the position of the piston in the cylinder In addition to the expansion machine and when the piston is at the initial extreme point of movement, it opens the inlet valve, as a result of which the combustion products entering the cylinder act on the piston, set it in motion, and when the piston arrives at the extreme end point of control, closes the inlet valve, opens the exhaust valve and during the reverse stroke of the piston, the exhaust gases are ejected from the cylinder, after which the next working cycle begins.

Industrial application

A piston engine powered by a working fluid from a free piston generator with a chamber will find application where a multi-fuel engine without mechanical power traction is required, for example, in open-cast cars.

Graphic material

Figure. Schematic diagram of a free-piston gas generator with an external combustion chamber.

1 - combustion chamber, 2 - nozzle, 3 - spark plug, 4, 10 - gas distribution valves, 5, 7 - pistons, 6 - stem, 8, 9, 11, 12 - check valves, 13 - damper.

Claims (1)

A piston engine powered by a working fluid from a free-piston gas generator with an external combustion chamber that converts the exothermic energy of motor fuel into mechanical energy of power take-off rotation includes a free-piston gas generator with an external combustion chamber, a piston expansion machine with inlet and outlet valves with an electropneumatic actuator, and a control system characterized in that to ensure the operation of the engine expansion machine, the control system monitors the position of the piston I in the cylinder of the expansion machine and when the piston is at the initial extreme point of movement, opens the inlet valve, as a result of which the combustion products entering the cylinder act on the piston, set it in motion, and when the piston arrives at the extreme end point of movement, the control system closes the inlet valve, opens exhaust valve and during the reverse stroke of the piston the exhaust gases are ejected from the cylinder, after which the next duty cycle begins.

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