SU1508001A1 - Free piston gas generator - Google Patents

Abstract

The invention relates to free piston gas generators and allows for improving the purging of a working cylinder of a double acting generator with one piston group by organizing a split exhaust under heavy loads. In addition to the standard purge and exhaust camshafts, additional outlets are made in the working cylinder, which are opened by movable sliders driven through a crank mechanism connected to the working cylinder. The effect of a split exhaust occurs when reciprocating the working cylinder of the generator, fixed on a fixed base, and moving spools at a sufficiently large oscillation amplitudes, reciprocates. 1 hp f-ly, 4 ill.

Description

This invention relates to two-stroke free piston engines and can be used as a gas generator.

The aim of the invention is to improve the purge of a free piston gas generator (SPGG) by implementing a split exhaust at high loads due to the forced opening of additional exhaust ports.

FIG. 1 shows the general scheme of LNG; in fig. 2 - spool discharge valve, closing the additional outlet window, and the drive mechanism of this valve; in fig. 3 - a spool mechanism that closes the additional exhaust port in connection with the flow diagrams of the cylinder, the additional exhaust ports and the valve as a function of piston movement; in fig. 4 is an SPGG indicator diagram in coordinates P (pressure) and V (volume of the cylinder cavity and valve timing).

The LNGG double action consists of cylinder 1 and piston 2. Cylinder 1 has end walls - heads-3 and 4 with inlet ports 5 and 6 and outlet ports 7. In cylinder 1 there is a piston 2 having projections 8 and 9. The piston divides the cylinder On upper (fig. 2) 10 and lower (fig. 2) 11 cavities.

The cross section dimensions of the protrusions 8, 9 correspond to the sizes of the windows 5, 6. To seal the gaps in the windows 5. 6 seals can be mounted on the protrusions 8, 9. Windows 5, 6 are closed by exhaust manifolds (not shown), which are also shrouds at the same time, preventing contact with the protrusions of the piston.

The cylinder is mounted on the basis of the movable and held by weak springs, the force of the preliminary tightening of which is equal to the strength of random effects, and with the vertical layout of the SPGG - the sum of the weight and these forces. The stiffness of the spring may be minimal, and the course of deformation must exceed the amplitude of oscillation of the cylinder.

With stiffer springs, the load on the foundation increases and even cylinder beats can occur, affecting

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on the stability of work cycles. If the springs are made weakly, so that the cylinder almost freely oscillates, the latter, due to the high cyclicity, moves a little away from the initial position (by 5–35 mm) and transfers very small loads to the foundation, equal to the force of weak springs at the indicated deformations.

If, by design considerations, it is possible to move the cylinder by a length X and the maximum amplitude of oscillation of the cylinder is A ,,, ah, the minimum spring stiffness is determined from the relations:

A - ,,, ". V-f ALc.,;

ALc., Where Af ate and ALt

Afc C

(2)

respectively, the strength of random effects and displacement under the action of this force;

C - spring stiffness. If a pre-tightening spring is used, the pre-tightening value is chosen such as to balance the random effects, and is also determined from relations (1) and (2). In the vertical arrangement, the weight is added to the strength of the random effects. From the standpoint of reliability, the best option is to implement SPGG, in which Windows 5, 6 in. Are inlet, i.e., are connected to the view collector, and windows 7 are in-out. In this embodiment, the length of the protrusions exceeds the stroke of the piston. Rational length of the protrusions is equal to the sum of the geometrical stroke of the piston and the length of the generatrix of the window in the head. The piston projections are hollow, the thickness is reduced but as far as the piston is removed. The latter is due to the fact that the loads caused by the inertia force decrease in the direction from the piston to the end of the projections. In the walls of the hollow parts of the projections there are slots 12.

In the piston, in order to cool it with incoming air, channels can be formed that extend into the hollow portion of the protrusions. Self-acting valves can be located in the channels. It is also rational to lubricate the pistons by making sealed, partially oil-filled cavities connecting the piston and the protrusions. These cavities can be turned into heat pipes, which will even better cool the piston.

In addition to this option, in which the windows 5, 6 are inlet, and the windows 7 are outlet, a variant is possible in which the windows 5, 6 are outlet — the outlet is through the slots and the inside of the hollow projections, and the windows 7 are inlet.

Using projections as inlets is better than using them.

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five

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five

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as organs of issue, in terms of reliability, heat resistance and strength. P., in fact, when the protrusions are elements of the intake organs, the cut-out part of the protrusions begins closer to their end. This allows an increase in the internal diameter, therefore, a reduction in weight. In addition, the reduction in weight is caused by a decrease in thermal stress. A is minimal on the cylinder length in this variant.

Due to the high frequency of cycles, obus ;; which shortens the gas exchange time, the best option for SPGG is an engine equipped with additional outlets (Fig. 1-3) 13 and 14, closed with additional valves - blocks 15 and 16. Valves of additional units There may be design differences (for example, self-acting valves, etc.). The design, ensuring the reliability and optimality of the gas distribution phase, is shown in FIG. 2, 3. In this embodiment of the output unit, the valves 17 are driven by a cylinder-and-piston mechanism, the crank 18 of which is connected by a connecting rod 19 to the cylinder 1. The crank of this mechanism is offset in an angle relative to the crank 21 and connected by a separate centerpiece 8 with valve 17.

The radius of the crank 21 is selected based on the amplitude of the cylinder moving at full load, and the radius of the crank 20 is based on the required amplitude of movement of the valve 17 (for axial mechanisms, the specified radii are equal to the corresponding amplitudes). The common axis of rotation 22 of the cranks 21 and 20 is associated with a fixed base. This bond may be rigid or allow some mobility (fixed with a rigid spring). Some adaptability to the mechanism may be made by the implementation of the rods of variable (in small limits) length. The center of rotation of the curved shots with respect to the window 13 is specially located on the side of the center of the cylinder. This is due to the fact that at the moment of the beginning of the opening, the directions of movement of the cylinder and the valve are opposite. Therefore, the window 3 opens quickly, which reduces the throttling of high energy gas. The opposite location of the specified center leads to a coincidence of the direction of the velocities of the valve and the cylinder at the moments of the beginning of the release, which reduces the speed of opening the outlet window. Additional exhaust valves of opposite cylinder cavities with rational organization of movement of these valves move along close trajectories. Therefore, additional exhaust valves of both cavities can be driven by one mechanism. For fuel supply and combustion, the LNGG cylinder is equipped with nozzles 23 or plugs and a corresponding fuel tank.

paratura. Combustion products may be discharged into two turbines connected to one another and to the consumer. You can use a set of SPGG, located in the form of a ring turbines or around them. This arrangement brings the outlet windows closer to the turbines. With single-cylinder SPGG, to increase the mass of gas passing through one turbine, additional outlets 13, 14 with valves — blocks 15, 16 — installed on these windows, are connected to one power turbine 24. A moving cylinder and a fixed turbine the operation of the SPGG as a gas generator for a turbine is mated with a movable sealing contact, which is made in the narrowest sections. For example, at the inlet or outlet of the collector.

In order to improve gas exchange, SPGG has a turbocharger whose turbine may be located behind the power turbine or behind the main exhaust manifold.

The operation of the additional exhaust valves shown in FIG. 1-3, based on the fact that the cylinder, fixed by movement (on the springs), moves upwards (FIG. 2) from the BDC cavity 10 to this cavity, the cylinder 1 moves down, and vice versa, when the piston moves down, cylinder upwards. The movement of cylinder 1 through crank 19 causes crank 21 to rotate. Crank 20 is rigidly connected to connecting rod 19 and angularly shifted relative to it in the direction opposite to the direction of rotation. Thus, the crank 20 repeats the rotational movement of the crank 21 with phase delay.

FIG. 3 on the left shows: half (to the axis) of the longitudinal section of the cylinder, a spool valve with a crank drive. In the same place, the arrows indicate the accepted directions of reference for intermixing the piston, cylinder and valve. Their upmixing (in FIG. 3) is considered positive, downward - negative. The zero position is assumed in which the piston is in the middle of cylinder 1 (cores. In the diagram on the right-hand side of Fig. 3, the displacement of the piston Sii .ip, as independent. The positive movement of the cylinder corresponds to the negative movement of the piston and vice versa. The position of the upper dead center and lower dead center for the “upper cavity 10” is marked on the drawing and on the coordinates.

The trajectories of the boundaries of the additional outlet window are marked SOK. Since the window is made in the cylinder, its trajectories are equidistant to the trajectories of the cylinder (the center of the cylinder). The trajectory of movement of the end of the spool valve 5kl is close to the ellipse with the axes rotated relative to the accepted axes of coordinates. Positions at which the end of the spool

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p 5

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is below the upper border of the window, corresponds to an open window. The distance at which the valve opened the window is depicted by hatching. With this distribution mechanism, the valve begins to open the TDC window (point 6). Expiration at this point does not occur, because the additional outlet port 13 is blocked by the side surface of the core. Then the valve opens the window completely (point b). When the piston approaches the center of the cylinder, to the main exhaust window 7, an additional exhaust valve closes the window (point c) with some overlap of the phases of the additional and main windows.

By changing the geometry1-; in the crank mechanism to the other units of this valve block and its drive, it is possible to carry out any specified valve timing. So, by increasing the length of the crank 20, you can reduce the duration of opening windows 13.

G1 {41 reducing the load decreases the amplitude of oscillation of the cylinder. As a result, cranks 20 and 2 do not go through a complete revolution. Their reciprocating (swinging) movement causes the valve 17 to remain closed.

SPGG can operate both in self-ignition cycle and in forced ignition cycle.

Consider the work SPGG diesel cycle.

When the piston moves downwards in the upper cavity 11 10, between the piston 2 and the head 3, the process of spreading occurs, shown on the indicator diagram (Fig. 4) of the curve between the volumes at points a and b. When the piston 2, moving down, passes the additional exhaust ports 13, the clan 17 opens these windows, the combustion products with high energy (pressure and temperature) go to the additional exhaust manifold and the power turbine 24 (the direction of movement of the combustion products from Windows 13 and 14 are shown by arrows in Fig. 1). After the power turbine, the products of combustion and flow to the turbine of the turbocompressor (in the variant, when the turbine of the latter is located after the turbine of the turbocompressor (TCR).

Due to the outflow of gas, the pressure in the cavity 10 drops and is approx. To the pressure in front of the power turbine P --.-. An indicator diagram of this process is depicted in FIG. 4 line bn. Upon further movement, the porpins 2 K. ianan 7 ii.i; iBno closes window 13, the outflow of combustion products decreases, and at point r it stops (curve bb). When the stump passes through the outlet port 7, the products of combustion are low, 1, aylepi rush out. Host 10 in this okpo and further in atmospheres} pl .; turbines} - TKR n depending on the varia; This is the location of the TCR. The pressure in the npii pilinda this im11111 and

becomes lower than the pressure at the compressor. This pressure is indicated by p. After further non-reproduc- tion of the porgni and associated with it the displacement of the protrusion 9, the slots 12 enter into the floor 10. Through these slots and the internal slope of the protrusion 9, the cavity communicates with the intake manifold and the compressor of the turbocharger. The air compressed in the latter enters cavity 10 and is filled. The movement of air through the inner part of the protrusion contributes to the removal of heat from the piston, which reduces its thermal intensity and improves the reliability of the SP GG. Next, moving down, the piston compresses the fresh charge in Cavity 11, and fuel is also fed there. After the required degree of compression in the cavity 1 1 is reached, self-ignition of the fuel occurs. The pressure in the cavity 1 1 rises sharply, with the result that the piston 2 stops moving downwards and begins to move upwards. In the cavity 10, as the piston moves upward, the filling continues and the extrusion of the remaining combustion products and purging into the windows 7 takes place. After upward movement of the piston and the protrusion 9 of the slot 12 bypasses the windows 6 in the head 3, the inlet stops. Then nopiuenb 2 passes through windows 7, which stops the ejection of the remnants of the products of combustion and purging.

During the subsequent movement of the piston upwards to the TDC cavity 10, the valve 17 still closes the window 13 (FIG. 3) and in zone 10 the compression of the fresh charge occurs (curve lm in Fig. 4), the fuel injection and self-ignition of the fuel. After the fuel burns, the pressure in cavity 10 increases (curve me –and farther), under the action of this pressure the piston moves downwards, the expansion stroke begins, etc. In cavity 11, the same processes occur, but are out of phase with respect to the processes in the cavity 10.

At low loads (small cyclic feeds of fuel), the amplitude of the cylinder and piston movements decreases and, as indicated above, the additional discharge window 13 remains closed during the entire cycle. The energy of the gas is expended on accelerating the piston and maintaining the operating state of the SPGG. Such self-regulation of SPGG is especially useful for idling, starting, when the gas energy is low and not enough to accelerate the piston and simultaneously drive a high-pressure turbine.

The main advantages of the proposed LNG are as follows. The split release, combined with the windows in the heads and the liner, provide good valve timing and gas exchange even at high frequency of SPGG cycles. This increases efficiency. The presence of hollow protrusions with slits on the piston allows the same piston to open and close the windows in the head and sleeve. A simple and durable mechanism allows the single-piston engine to open additional exhaust ports on the expansion stroke without opening them on the compression stroke. These gas distribution mechanisms are simpler and more reliable than the known ones.

In addition, the mechanism for opening additional outlet windows does not open these windows on low load and start modes, which improves the start and increases the efficiency on these loads.

Claims (2)

1. A two-way, free-piston gas generator mounted on a stationary base, containing a piston group and a working cylinder with end walls and inlet openings located in its middle part and connected to the supercharger and outlet openings connected at least with one gas turbine, characterized in that, in order to improve the purge, the cylinder is installed with the possibility of limited axial movement and is equipped with at least two additional exhaust ports, placed Between the inlet openings and end walls, and spool locking bodies connected through rods to a shaft mounted on a fixed base, driven by an additional crank and a connecting rod coupled to the working cylinder, the curvatures are mounted offset by the angle of rotation of the shaft. 2. The generator according to claim 1, wherein that the piston group is provided with hollow end guide rods, and the exhaust ports are made in the form of radial channels on the lateral surface of the rods.  sixteen  Z3 1 lzha Bleed pressure gases GC RK S powder