RU2776460C1 - Two-stroke piston internal combustion engine - Google Patents

Abstract

FIELD: internal combustion engines.

SUBSTANCE: invention can be used in internal combustion engines. A two-stroke reciprocating internal combustion engine contains a block of cylinders (16) equipped with purge and exhaust ports (11), (12) and pistons (7), (8) moving in the cylinders in opposite directions. Each of the pistons controls scavenging and exhausting, respectively. There is a mechanism with two degrees of freedom for converting the reciprocating motion of the pistons into the rotational motion of the crankshaft (1) by means of one common connecting rod (2) and pivotally connected through the rod (5), (6) with each of the pistons (7), (8), through rocker arms (3), (4) swinging on hinges (9), (10) with a fixed center. The rocker arms (3), (4) are connected to a common connecting rod (2) by means of sliders and an arcuate link having a common pin with the connecting rod head (2).

EFFECT: increasing fuel efficiency and improving the specific weight and size indicators.

2 cl, 12 dwg

Description

The technical field to which the invention belongs

The invention relates to engine building, in particular to the device of piston internal combustion engines (ICE).

State of the art

In engine building, ICE designs are known, in particular reciprocating ones, in which the processes of air charge intake, compression, expansion (stroke), and exhaust gases are carried out. And only the working stroke is related to the conversion of the chemical energy of the fuel, as a result of its oxidation (combustion), into useful work.

Known principle of self-organization of work processes in internal combustion engines, described in the newsletter "Ideas. Hypotheses. Decisions” No. 1, 2000, p. 31, as an intellectual product with registration number 70990000104, author - Korenevsky G.V. [one]. According to this principle, to convert the reciprocating motion of the pistons into the rotational motion of the crankshaft, a mechanism with 2 (two) degrees of freedom can be used, due to which the thermomechanical system, which is the internal combustion engine, itself chooses the best option for the process of converting heat into work: " due to the excess degree of freedom, the process of obtaining mechanical energy is now (almost) not connected with the process of its removal to an external consumer. A significant amount of mechanical energy (kinetic) circulates in the links of the ICE mechanism and can be given to the consumer at any time with efficiency. close to 100%” [1]. This principle is implemented in the method of operation of a two-stroke piston internal combustion engine with oppositely moving pistons (PDP) [2].

In the specified ICE with PDP, to convert the reciprocating motion of the pistons into the rotational motion of the crankshaft, a mechanism with 2 (two) degrees of freedom is used, which makes it possible to implement a method of operation in which the pistons move in the absence of a rigid kinematic connection with the position of the crankshaft and thereby create conditions for the occurrence of self-oscillations of the pistons, which are not transmitted directly to the crankshaft, but generate additional flows of kinetic energy circulating in the moving links of the mechanism for converting the movement of the pistons.

Known two-stroke diesel engine with PDP [3], which uses a mechanism for converting the reciprocating motion of the pistons into the rotational motion of the crankshaft, consisting of one main connecting rod, trailer connecting rod and two rocker arms pivotally connected through the piston rod. The trailing connecting rod is connected via a rocker arm to the control piston, and the main connecting rod is directly connected via a rocker arm to the blowdown control piston. The main problem solved by the specified invention was the creation of a block design of the engine, which makes it possible to multiply the engine power by assembling the same type of sections. Due to the fact that the distance between the centers of the hinges of the main and trailer connecting rod is variable in the specified engine, various forms of dependence of the stroke of the exhaust and purge pistons on the angle of rotation of the crankshaft (c.c.v.) and a favorable phase shift of the opening of the exhaust and purge windows. The specified engine is a mechanism with the 1st (one) degree of freedom, which means the presence of a rigid connection between the angle of c.c.v. and the position of each of the pistons and the lack of the possibility of influencing the workflow based on the principle of self-organization.

Known ICE with PDP [4], which implements the method of operation [2] through the use of a mechanism for converting the reciprocating motion of the pistons into the rotational motion of the crankshaft by means of one common connecting rod and two rocker arms pivotally connected through the rod with each of the pistons, while the rocker arms have fixed centers of swing and are connected to a common connecting rod with the help of two-movable hinge-hinge joints with eccentric necks.

Specified in [4] the engine according to the set of features closest to the set of essential features of the invention can be selected as a prototype.

The aim of the invention is to increase the efficiency of the internal combustion engine, in which the conversion of the reciprocating motion of the pistons into the rotational motion of the crankshaft is carried out through the use of a mechanism with 2 (two) degrees of freedom, provided by the connection of the connecting rod head with the rocker arms by means of sliders and arc wings.

Disclosure of invention

This goal is achieved by the fact that in a known two-stroke piston internal combustion engine containing a cylinder block equipped with purge and exhaust ports, pistons moving in these cylinders in opposite directions, each of which controls purge and exhaust, respectively, a mechanism for converting reciprocating motion pistons into the rotational movement of the crankshaft by means of one common connecting rod and pivotally connected through the rod with each of the pistons of two rocker arms, swinging on hinges with a fixed center, while the rocker arms are connected to a common connecting rod by means of sliders and an arcuate link having a common pin with the connecting rod head and anti-rotation device.

The differences between the claimed two-stroke piston internal combustion engine from traditional internal combustion engines and the prototype can be seen from their analysis as mechanisms with 1st and 2nd degrees of freedom.

On FIG. 1a is a diagram of an internal combustion engine with a PDP according to [3], from which it can be seen that the crank 1, connecting rod 2, trailer connecting rod 2a, rocker arms 3 and 4, rods 5 and 6, pistons 7 and 8 are a set of nine (n=9) links connected by 11 (eleven) hinges and 2 (two) sliding pairs (piston-cylinder). Thus, there are 13 kinematic pairs of the 5th class (p ₅ =13). Using the A.P. Malyshev for the number of degrees of freedom of a flat mechanism gives the result:

w=3n-2p ₅ =3*9-2*13=1.

On FIG. Figure 1b shows a diagram of an internal combustion engine with a PDP prototype [4] with an additional link, which is the eccentricity 3e (4e) between the hinge necks (the images of the link and the differences in the angles between the arms of the rocker arms are disproportionately increased), which also provides the mechanism with the 2nd degree of freedom:

n=10 - number of moving links;

p ₅ \u003d 14 - the number of single-moving kinematic pairs of the 5th class

w=3n-2p ₅ =3*10-2*14=2

In the claimed ICE with PDP, a conventional double-hinged connecting rod is used, the head of which has an add-on in the form of an arcuate backstage with two conical guides along which two pairs of sliders move. Comparison of circuits in Fig. 1b and in Fig. 1c shows that the replacement of rotation pairs (hinges) with sliding pairs (sliders) in the connecting rod head does not reduce the number of single-moving kinematic pairs of the 5th class p ₅ =14, and therefore provides the mechanism with the 2nd degree of freedom.

In the presence of one more degree of freedom, which is redundant compared to traditional internal combustion engines, each fixed position of the crankshaft will no longer correspond to a strictly defined position of the pistons; it will be set dynamically, based on the processes taking place in the over-piston space.

Brief description of the drawings

On FIG. 1 shows images related to the scheme of the traditional internal combustion engine mechanism (Fig. 1a), the prototype (Fig. 1b) and the proposed one (Fig. 1c).

On FIG. 2 shows a longitudinal (through the axis of the cylinders) section of the proposed internal combustion engine. Auxiliary mechanisms and units are not shown.

On FIG. 3 shows an enlarged image of the connection of the connecting rod head with the rocker arm by means of an arcuate link and pairs of sliders.

On FIG. 4 shows the contour of the possible movements of the connecting rod head.

On FIG. 5 shows an isometric view of the arc stage.

On FIG. 6 shows isometric images of a finger and pairs of sliders (right-hand assembly with a finger).

On FIG. 7 shows the dependence of the change in the total stroke of the pistons on the angle of c.c.v. and comparing it with that of a traditional ICE with a PDP with two crank mechanisms (CC - combustion chamber).

On FIG. 8 shows the dependence of the current degree of expansion on the angle of c.c.v. for traditional and proposed ICE.

On FIG. 9 shows the dependence of the angular acceleration of the connecting rod on the angle of c.c.v.

On FIG. 10 shows the dependence of the kinetic energy of the ICE links on the angle of c.c.v.

Implementation of the invention

The invention can be implemented in the form of the device shown in FIG. 2 and with details in FIG. 3. The implementation of the invention involves the use of oppositely moving pistons 7 and 8 connected by rods 5 and 6 with rocker arms 3 and 4, respectively. The transformation of the rocking movements of the rockers 3 and 4 into the rotational movement of the crank 1 occurs due to the use of a double-hinged connecting rod 2. An additional, 2nd degree of freedom of the mechanism for converting the reciprocating movement of the pistons 7 and 8 into the rotational movement of the crank neck 1 is provided by two pairs of sliders 3a and 4a moving along the conical guides of the arc stage 2a, connected with a finger to the connecting rod head 2.

The operation of the described device is carried out as follows.

In the position of the mechanism in the region of the volumetric bottom dead center (BDC), the exhaust windows 12 are fully open and the free exhaust of exhaust gases into the exhaust manifold 14 has ended, the purge windows 11 are in the opening stage and through them air enters the cylinder 16 from the air manifold 13 and displaces the exhaust gases . When the crank 1 rotates (clockwise), the outlet windows 12 are the first to close and air is blown. Next, purge windows 11 are closed and the process of compressing the air charge begins. In the variant of the diesel operating process with compression ignition in the region of volumetric top dead center (TDC), fuel is supplied through the nozzle 15 into the combustion chamber formed by the bottoms of the pistons 7 and 8 and the walls of the cylinder 16. In the variant of the working process with external carburetion and positive ignition, the nozzle (not shown) can be located in front of the purge windows 11. After the pistons 7 and 8 have passed the volumetric TDC, the combustion process of the fuel is completed and the process of gas expansion begins with the completion of useful work. Before reaching the geometric BDC of the piston 8, the exhaust windows 12 open and the free release of exhaust gases into the exhaust manifold 14 begins. Further, before reaching the geometric BDC of the piston 7, the purge windows 11 open and the forced exhaust of the exhaust gases begins, replacing them with purge air, i.e. . purge process. The two-stroke cycle is completed.

The presence of the 2nd degree of freedom of the mechanism for converting the reciprocating movement of the pistons 7 and 8 into the rotational movement of the crank journal 1 means that each fixed position of the crank 1 can correspond to many positions of the connecting rod head 2 between its two extreme positions, in which the axis of the connecting rod pin 2 is located at the maximum distance from the swing centers of the rocker arms 3 and 4. If we assume that the centers of the hinges 9 and 10 are located symmetrically with respect to the plane passing through the axis of rotation of the crank 1 and the center of the combustion chamber (i.e. the vertical plane, in relation to Fig. 2), and the length of the arms of the rocker arms 3 and 4 adjacent to the connecting rod 2 is the same and equal to R, as in Fig. 3, then the specified maximum distance will be equal to R + r, where r is the radius of the trajectory of the centers of the sliders 3a and 4a, relative to the axis of the pin connecting the connecting rod head 2 and the arcuate link 2a. Arcs with radius R+r, drawn from the rocker centers of rockers 3 and 4, limit the area of possible positions of the axis of the connecting rod head 2. Other restrictions of this area are arcs with a radius equal to the length of the connecting rod 2, drawn from the center of the neck of the crank 1 in its upper (0 deg, n .k.v.) and in its lower (180 degrees, p.k.v.) positions. Together, these 4 (four) constraints form a region that is well approximated by an ellipse, as in FIG. 4 whose vertical axis is 5-6 times larger than the horizontal axis. Taking into account the remarks made, we can assume that the axis of the connecting rod head 2 can touch either the right or left arc of the specified ellipse.

An embodiment of the arc stage 2a in the form of two identical clips with two conical guides is shown in Fig. 5. An embodiment of sliders 3a and 4a and pins 3b and 4b (the latter assembled) is shown in FIG. 6.

A certain direction of rotation of the crank 1 (for example, clockwise) leads to the fact that the angular acceleration of the connecting rod 2 changes from the angle of c.c.v. according to a law close to sinusoidal, with maxima (in absolute value) in the region of 90 and 270 degrees, p.c.v., as in Fig. 9. The moment of inertia of the connecting rod 2, the arcuate wings 2a, the sliders 3a and 4a, acting relative to the center of the neck of the crank 1 leads to asymmetry in the distribution of forces applied to the head of the connecting rod 2 from the side of the rocker arms 3 and 4. Thus, the resultant of the forces applied to the head connecting rod 2, will pass along the axis of its symmetry only in the positions of the crank at 0 and 180 degrees, p.k.v. In all other cases, the connecting rod head 2 will always be affected by the horizontal component of the resultant forces, which will tend to deflect the connecting rod head towards the right or left arc of the mentioned ellipse.

If we impose a restriction on the movement of the connecting rod head 2 strictly in a vertical straight line ("virtual crosshead"), i.e. reduce the number of degrees of freedom of the mechanism by 1 (one), then with the same shape and size of the parts responsible for the release and purge (piston, rod, rocker arm), the dependences of the piston stroke on the angle of c.c.v will be identical in shape and symmetrical with respect to volumetric TDC . This circumstance excludes the possibility of effective blowing, which is typical for internal combustion engines with PDP, having an angular mismatch of the crankshafts of the order of 10-12 degrees, c.c.v.

In the claimed ICE with PDP with 2 degrees of freedom, the asymmetry of the dependences of the stroke of the purge and exhaust pistons on the angle p.k.v. achieved in a natural way, due to the constant direction of the inertial forces of the connecting rod during the compression / expansion stroke.

The main consequence of the presence of the 2nd degree of freedom is that the fixed position of the crank 1 does not correspond to any fixed position of the pistons 7 and 8, as in any other traditional piston ICE. In this case, self-oscillations of the pistons arise, which generate additional flows of kinetic energy in the moving parts of the mechanism, however, in the initial consideration of the advantages of the proposed internal combustion engine, such effects can be neglected and, by imposing a restriction on the movement of the connecting rod head strictly along the left / right arcs of the mentioned ellipse, conditionally lower the degree of freedom of the mechanism by 1 (one).

An example of a possible implementation of the proposed ICE.

As an analogue, the internal combustion engine [5] of a sports aircraft, a 3-cylinder diesel engine with a PDP "Gemini-100" with S/D=2×72/69, power N _e =15 kW, with a crankshaft speed of n=4000 rpm

Initial data:

1. Power - 80 kW (2 cylinders)

2. RPM k.v. - 4000 rpm

3. Piston stroke - 2×82 mm

4. Cylinder diameter - 80 mm

5. Working volume - 1.6 l

6. Crank radius - 45mm

7. Connecting rod length - 130 mm

The asymmetry of the dependences of the piston stroke S _vy and S _inlet on the angle of c.c.v. relative to the geometric TDC and their phase shift (40 degrees, c.c.v.) lead to the fact that the dependence of the total piston stroke S _pdp on the c.c.v. in the region of volumetric TDC is much flatter than that of an internal combustion engine with a traditional crank mechanism S _deg , as shown in Fig. 7, and also manifests itself in the fact that the change in the volume of the over-piston space in the proposed ICE is slower than in the traditional one (see Fig. 8). This means that the process of heat release (combustion) proceeds as close as possible to isochoric (V=const), which is characterized by the highest thermal efficiency, all other things being equal. The specified phase shift is also favorable for the implementation of once-through purge in the process of gas exchange.

In the calculation model of the internal combustion engine, the masses of the piston, rod and rocker are taken, reduced to the mass of the piston in the amount of 2 kg. The masses of the backstage, sliders and fingers are taken in the amount of 3 kg. The mass of the connecting rod is assumed to be 2 kg. The moment of inertia of a connecting rod with an arcuate link relative to the center of mass, located from the axis of the pin at a distance of 20% of the length of the connecting rod, is taken in the amount of 0.025 kg * m ² .

The calculation of an internal combustion engine with 2 degrees of freedom requires significant computational resources, therefore, the parameters of the proposed internal combustion engine were estimated using a boundary model in which restrictions imposed on the movement of the connecting rod head reduce the number of degrees of freedom by 1 (one). The area of possible positions of the axis of the connecting rod pin is limited by the arcs of the ellipse, as in Fig. 4 and dynamic calculations are performed in two versions: for the left / right border, as a starting point for the compression process.

With the accepted direction of rotation of the crankshaft (clockwise) under the action of a moment from the forces of inertia, the connecting rod head will deviate during compression (from 0 to 180 degrees, c.c.v.) to the left border, and during expansion (from 180 to 360 degrees, p.k.v.) - to the right.

From FIG. 9 it can be seen that in the range of angle c.c.v 180-225 degrees, the angular acceleration of the connecting rod is not sensitive to the deviation of the connecting rod head, and hence the moment of forces acting on the connecting rod cannot affect the nature of the self-oscillations of the pistons.

From FIG. 10 it can be seen that when the process of compression is carried out along the left border (expansion - along the right one), the links of the mechanism (excluding the crankshaft) have a greater kinetic energy (without a component from the portable movement of the center of mass of the connecting rod and backstage) than in the case of choosing the initial right border. This means that when the connecting rod head is shifted, it is possible to accumulate mechanical energy without its instantaneous transfer to the engine flywheel. Thus, the thermomechanical system itself can "choose" the trajectory of the connecting rod head, which is the realization of the principle of self-organization of work processes in the internal combustion engine.

With the accepted cylinder power of 40 kW, the cyclic fuel supply will be of the order of 0.035 g/cycle, which, with the calorific value of the fuel Q _p =42.7 MJ/kg, will provide heat release of 1.5 kJ/cycle. Let 80% of heat be released in 1/10 of a turn (36 degrees, r.c.v.). Then the heat release power will be dQ/dt=1.5*0.8*4000*10/60=800 kW. In the range of 180-225 degrees, p.c.v. the difference in the kinetic energy of the mechanism in the extreme positions of the connecting rod head varies from 300 to 100 J (see Fig. 10). Let the relocation of the connecting rod head occur in 10 degrees, c.c.v., or 60/4000/360 * 10 = 0.417 ms, and during this time the mechanical energy will increase by 100 J. Then the power stored in the links of the mechanism will be dN _mech = 100*10 ^3/ /0.417=240 kW, which is commensurate with the heat release power. The actual vibrations of the connecting rod head can be an order of magnitude smaller, but it is fundamentally important that the process of converting heat into work is now not strictly related to the return of useful work to the engine flywheel.

Thus, the proposed engine provides the achievement of a technical effect, which consists in increasing fuel efficiency, improving the specific weight and dimensions. The engine can be implemented using means known in the art. Therefore, the proposed engine has industrial applicability.

Since the preferred embodiments of the present invention will be apparent to those skilled in the art of engine construction and the invention itself is susceptible to many variations, modifications and changes in detail, it is intended that all material contained in the foregoing description or shown in the accompanying drawings is to be interpreted as illustrative and not in restrictive sense.

Sources of information:

1. “Ideas. Hypotheses. Solutions". News bulletin. - Moscow, VNTIC No. 1, 2000, p. 31

2. Pat. EN 2729562, 2020

3.Pat. US 2237113, 1941

4. Pat. EN 2739105, 2020

5. https://www.geminidiesel.aero

Claims (2)

1. A two-stroke reciprocating internal combustion engine containing a cylinder block equipped with purge and exhaust ports, pistons moving in said cylinders in opposite directions, each of which controls purge and exhaust, respectively, a mechanism with 2 (two) degrees of freedom for converting reciprocating movement of the pistons into the rotational movement of the crankshaft by means of one common connecting rod and pivotally connected through the rod with each of the pistons of two rocker arms, swinging on hinges with a fixed center, characterized in that the rocker arms are connected to a common connecting rod by means of sliders and an arcuate link having a connecting rod head common finger. 2. A two-stroke piston internal combustion engine according to claim 1, characterized in that the arc link has a means of fixation relative to the connecting rod head, excluding its rotation on a common pin.

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