RU209665U1 - Volumetric piston machine - Google Patents

Abstract

The utility model relates to the field of mechanical engineering and can be applied in internal and external combustion engines, compressors, expansion machines, in lightly loaded engines of special schemes for special purposes. The objective of the utility model is to increase the technical and economic efficiency of volumetric reciprocating machines. the fact that the approximately rectilinear movement of the rods articulated with the pistons and their minimum angular deviation from the cylinder axis are provided by a mechanism with strictly defined geometric relationships, such as: the coordinates of the horizontal axis of the rocker arm relative to the horizontal axis of the crankshaft, the distance between the horizontal axis of the crankshaft and the axis of the cylinder, the distance between the centers of the hinges of the connecting rod and the angles between the segments connecting the centers of the hinges of the connecting rod, the length of the rocker. scarlet connected to the rocker. The change in the angular position of the eccentric shaft is carried out by a special mechanism. Due to the fact that the rods are articulated with the pistons and the connecting rod, the possibility of jamming of the mechanism is excluded. stroke) will be carried out within 240° of the angle of rotation of the crankshaft, i.e. the working cycle will be carried out with the continued expansion of the working body.

Description

The utility model relates to the field of mechanical engineering and can be used in internal and external combustion engines, compressors, expansion machines, in lightly loaded engines of special schemes for special purposes.

Of the known technical solutions, the closest in technical essence is a volumetric piston machine [Author's certificate 323562, declared 02.1.1968 (No. in which two pistons are installed, rigidly connected to each other by a rod.To articulate the rod with the crankshaft, the Chebyshev mechanism is used, formed by a shaft knee, a rocker arm and a connecting rod, which is an isosceles triangle, at the tops of which hinges are fixed. A rod is attached to one of the hinges, to the second - the rocker, to the third - the knee of the shaft.

Significant disadvantages of the prototype are:

a) Rigid articulation of the rod with the pistons, which, in the presence of an approximately rectilinear movement of the rod and the inevitable presence of lateral forces on the piston from the connecting rod, as well as the combined effect of all forces acting in the mechanism, will lead to jamming of the mechanism;

b) Specific geometric ratios of the mechanism are not defined (such as: the coordinates of the horizontal axis of the rocker arm relative to the horizontal axis of the crankshaft, the distance between the horizontal axis of the crankshaft and the axis of the cylinder, the distance between the centers of the connecting rod hinges and the angles between the segments connecting the centers of the hinges of the connecting rod, length rocker arms), providing the minimum possible deviation of the trajectory of the rod, articulated with the pistons, from a straight line, as well as its minimum angular deviation relative to the axis of the cylinder (Fig. 1);

c) There is no property of the mechanism to change the stroke of the pistons, which negatively affects the improvement of the technical and economic efficiency of volumetric piston machines.

The objective of the utility model is to improve the technical and economic efficiency of volumetric reciprocating machines. The use of the proposed utility model allows to obtain a number of positive technical results, namely:

- increasing the time to overhaul, reliability and durability of volumetric reciprocating machines;

- reduction of operating costs;

- the ability to change the stroke of the pistons in the required range of the crankshaft speed, which, in turn, will allow you to change the degree of compression and expansion;

- an increase in the efficiency of volumetric piston machines in comparison with machines in which a prototype mechanism is used;

The indicated technical results are achieved due to the fact that the approximately rectilinear movement of two separate rods, each of which is articulated with the corresponding piston, and their minimum angular deviation from the cylinder axis are provided by a mechanism with strictly defined geometric relationships, such as: the coordinates of the horizontal swing axis rocker arms relative to the horizontal axis of the crankshaft, the distance between the horizontal axis of the crankshaft and the axis of the cylinder, the geometric ratios of the isosceles triangle forming the connecting rod (the distance between the centers of the connecting rod hinges and the angles between the segments connecting the centers of the hinges of the connecting rod), the length of the rocker arm.

The change in the stroke of the pistons, and, consequently, the degree of compression and expansion, is provided by an eccentric shaft connected to the rocker arm. The change in the angular position of the eccentric shaft is made by a special mechanism.

An increase in the efficiency of volumetric piston machines is achieved due to the fact that the conversion of the internal energy of the working fluid into mechanical energy (working stroke) will be carried out within 240 ° of the crankshaft rotation angle, i.e. the working cycle will be carried out with the continued expansion of the working body. This is facilitated by the quality of the Chebyshev mechanism, as well as the strictly defined geometric relationships presented, which the mechanism must comply with.

The utility model is illustrated by the following description and the accompanying diagrams, where in Fig. 1 is a block diagram of the mechanism, in Fig. 2 is a diagram of the operation of the mechanism when the stroke of the pistons changes, fig. 3 - alternation of cycles depending on the angle of rotation of the crankshaft, as applied to an internal combustion engine.

In the block diagram (see Fig. 1) the following designations are accepted:

r is the crank radius of the crankshaft 5;

S - piston stroke;

L is the length of the rocker;

D is the distance from the horizontal axis of the crankshaft 8 to the horizontal axis of rocker arm 9 in the horizontal plane;

E is the distance from the horizontal axis of the crankshaft 8 to the horizontal axis of rocker arm 9 in the vertical plane;

e - eccentricity (distance from the horizontal swing axis of the rocker arm 9 to the horizontal axis of the eccentric shaft 10);

A, B, C - designation of the sides of an isosceles triangle forming a connecting rod 4 (where B=C);

M is the distance between the horizontal axis of the crankshaft 8 and the axis of the cylinder 11 (desaxage).

To ensure approximately rectilinear reciprocating motion of the rods and their minimum angular deviation from the cylinder axis, the mechanism must have the following geometric relationships:

S=3.5r;

A=3.5r;

B=C=2r;

R=L=2r;

D=r;

E=2r

In order to change the stroke of the pistons, the mechanism contains an eccentric shaft 7 pivotally connected to the rocker arm 6.

The work of the volumetric piston machine proposed in the utility model, as applied to an internal combustion engine, is as follows. On the intake, compression, stroke and exhaust strokes during the movement of the pistons 2, each of which is articulated with the rods 3, in the cylinder 1, the kinematics of the mechanism changes in such a way that the rocker arm 6 ensures that the articulation of the connecting rod 4 with the rods 3 is kept on an approximately rectilinear trajectory , concentric to the axis of the cylinder 11, i. e. the minimum deviation of the trajectory of the articulation of the connecting rod 4 with the rods 3 from a straight line is ensured. The minimum angular deviation of the axes of the rods 3 from the axis of the cylinder 11 is also provided. Due to the fact that the rods 3 are articulated with the pistons 2 and the connecting rod 4, the possibility of jamming of the mechanism is excluded. In this case, the full stroke of the pistons 2 (from the extreme upper to the extreme lower position) is provided for the angle of rotation of the crankshaft equal to 240°, which allows continued expansion of the working fluid and a much more efficient cycle of the working stroke.

In FIG. 3 shows the duration of the stroke, in relation to the internal combustion engine, expressed in the angles of rotation of the crankshaft.

The change in piston stroke occurs as follows. When the eccentric shaft 7 is rotated (see Fig. 1) with an eccentricity e by a certain angle, the position of the rocking axis of the rocker arm 9 changes, which, in turn, leads to a change in the kinematics of the connecting rod 4, rods 3 and pistons 2 (see Fig. 2) . This changes the stroke ΔS of the pistons 2 (in comparison with the initial position). In FIG. 2 shows the positions of the links of the mechanism in the initial position and in the position when the piston stroke changes. At the same time, changing the stroke of the pistons makes it possible to change the degree of compression and expansion and to carry out a more efficient thermodynamic cycle with continued expansion of the working fluid.

The volumetric piston machine proposed in the utility model with the design of the mechanism for converting the reciprocating movement of the piston into the rotational movement of the crankshaft with the possibility of changing the stroke of the pistons makes it possible to increase the technical and economic efficiency of volumetric piston machines.

Claims (1)

Volumetric piston machine, including a fixed cylinder, two pistons installed in it, a Chebyshev mechanism formed by a crankshaft, a rocking rocker arm and a connecting rod, which is an isosceles triangle, hinges are fixed at the tops of the triangular connecting rod, a rocker arm is attached to the second hinge, a crankshaft is attached to the third one, characterized in that the machine is equipped with two separate rods and an eccentric shaft, wherein two separate rods are articulated with the pistons and with the first hinge of the connecting rod, and the eccentric shaft is articulated with the rocker arm.

Images