RU2494286C1 - Engagement of screw-type machine - Google Patents

Abstract

FIELD: machine building.

SUBSTANCE: gear engagement of a screw-type machine with an asymmetric profile of teeth of drive and driven rotors, in which the profile of rear part of a cavity in rotation direction, which is the profile of a root of tooth of the driven rotor, is smoothly adjacent to its outside circumference. The corresponding section of the profile of the drive rotor tooth is made along the curve of rolling of the drive rotor tooth along the tooth profile of the driven rotor. Curve of profile of rear part of the cavity in rotation movement of the driven rotor within pitch circle represents elongated epicycloid 1 formed with the curve of rolling of the drive rotor tooth top. Connection of the profile of the rear part of the cavity of the driven rotor in rotation movement to outside circumference is made through sections of loops 2, 4 of Bernoulli lemniscates connected to each other, one of which is connected to outside circumference of the driven rotor and the other one is connected to elongated epicycloid 1.

EFFECT: increasing efficiency of a machine, reduction energy losses at contact points, reducing leaks between compression cavities.

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Description

The invention relates to compressor technology, namely to screw compressors and can be used in expansion machines.

It is known that a helical machine engages with an asymmetric tooth profile of the driving and driven rotors, in which the back profile along the rotation of the cavity part, which is the tooth profile of the driven rotor tooth, smoothly mates with its outer circumference, and the corresponding tooth profile section of the driving rotor is made along the rolling curve of the leading tooth the rotor along the tooth profile of the driven rotor, and the profile curve of the driven rotor within the initial circle is made in the form of an elongated epicycloid formed by the rolling curve of the top of the tooth of the Vedas conductive rotor (see. Author's certificate SU 1401158, published on 06.07.1988).

It is known that the main criteria for evaluating profiles are energy and weight and size indicators, determining the length of the contact line, the size of the triangular gap, the pinched volume and the area of the cavity between the teeth of the rotors.

One of the disadvantages of the known engagement is the high pressure angle. As you know, in the place of contact of the screws there are energy losses associated with the friction of surfaces against each other. With a decrease in the pressure angle, these losses decrease, the load capacity increases, since decreasing energy losses lead to a decrease in tooth wear.

Another disadvantage of this profile is the increased triangular gap between the compression cavities (when the corresponding pairs of teeth enter the mesh), which leads to an increase in leakages between the compression cavities, a decrease in the feed coefficient and efficiency. The triangular gap is the minimum cross section of a spatial channel of complex configuration, which connects adjacent compression cavities if the contact line of the screws at a point does not reach the crest of the housing bore. Through a triangular gap, gas from a cavity with a higher pressure flows into a cavity with a lower pressure. The walls of the slit in this plane are formed by the lateral surfaces of the driving and driven rotors and the crest of the body bore.

The technical result of the invention is to increase the efficiency of the machine, reducing energy losses at the contact points, as well as reducing leakage between compression cavities.

The specified technical result is achieved through the use of gearing of a screw machine with an asymmetric profile of the teeth of the driving and driven rotors, in which the profile of the back part of the cavity, which is the profile of the tooth of the driven rotor, smoothly mates with its outer circumference, and the corresponding section of the tooth profile of the driving the rotor is made according to the curve of running the tooth of the leading rotor along the tooth profile of the driven rotor, and the profile curve of the rear along the rotation of the cavity part of the driven rotor within of the initial circle is an elongated epicycloid formed by the rolling curve of the top of the tooth of the driving rotor, while the profile of the back along the rotation of the cavity part of the driven rotor with the outer circle is made through mutually connected sections of the Bernulli lemniscate loops, one of which is paired with the outer circle driven rotor, and the other with an elongated epicycloid.

In addition, conjugation of sections of the Bernoulli lemniscate loops can be performed by means of a straight line segment whose ends lie on the centers of the corresponding Bernoulli lemniscate and which lies on a straight line passing through the axis of rotation of the driven rotor.

In addition, the sections of the corresponding loops of the corresponding Bernoulli lemniscates can be mated directly, while the centers of the Bernoulli lemniscates coincide, and the tangent to the Bernoulli lemniscates at the point of their mating with each other passes through the axis of rotation of the driven rotor.

The invention is illustrated by drawings, where figure 1 shows the profile of the rear along the rotation part of the cavity of the driven rotor; figure 2 is the same with the image of the loops of Bernoulli lemniscate, figure 3 shows the profile of the back along the rotation of the tooth side of the driving rotor.

The gearing of a screw machine, for example, a compressor with an asymmetric tooth profile of the driving and driven rotors, has teeth with convex and concave surfaces. The teeth of the driving rotor have a convex shape, and the teeth of the driven rotor are concave, and the depressions of adjacent teeth of the driven rotor form the rear and front sides in the direction of rotation. The profile curve of the rear part of the depression of the driven rotor along the initial circle d _{2H is} made in the form of an elongated epicycloid 1 formed by the rolling curve of the tooth tip of the driving rotor. 1 epicycloid smoothly joined to the outer circumference of the tooth ₂ d. The conjugation of the epicycloid 1 with the outer circumference d _{2 of the} tooth is carried out through the section of the loop 2 of the first Bernully lemniscate, the straight segment 3 and the section of the loop 4 of the second Bernoulli lemniscate. The ends of segment 3 are located within the initial circle d _2H and lie on the centers of the corresponding Bernoulli lemniscates at points E ₂ and G ₂ . Section G ₂ H ₂ loop 2 of the first lemniscate Bernoulli smoothly mates one end (point G ₂ ) of segment 3 with the outer circumference d _{2 of the} driven rotor at point H ₂ . Section F ₂ E _{2 of} loop 4 of the second Bernoulli lemniscate smoothly mates the other end (point E ₂ ) of segment 3 with epicycloid 1 at point F ₂ (figure 2).

The teeth profile of the driven and driving rotors is designed in such a way that the best flow around the tooth profile of the driving rotor with the best contact angle (pressure) is ensured, i.e. with its reduced value. As a result, the triangular gap between the cavities of greater and lesser pressure decreases.

Thus, the rear part of the tooth cavity of the driven rotor along the rotation is described by the following curves: a straight segment 3, located at an angle α to the О ₂ А ₂ axis, two Bernoulli lemniscates and an epicycloid 1, which is the profile of the tooth of the driven rotor tooth and lying on section A ₂ F ₂ .

Section A ₂ F _{2 is} made in the form of an elongated epicycloid formed by a point A _{1 of the} outer circumference d _{1 of the} driving rotor while rolling its initial circle d _1H along the initial circumference d _{2H of the} driven rotor;

. Оси первой лемнискаты повернуты относительно отрезка 3 на угол 45°, а пересечение осей совпадает с точкой G₂, что обеспечивает плавное сопряжение с отрезком 3.The plot of G ₂ H ₂ loop 2 of the first Bernoulli lemniscate is described by the equation $${\left(x^2+y^2\right)}^2-2a^2\left(x^2-y^2\right)=0$$

. The axes of the first lemniscate are rotated relative to segment 3 by an angle of 45 °, and the intersection of the axes coincides with the point G ₂ , which ensures smooth conjugation with segment 3.

The axis of the second Bernoulli lemniscate is rotated relative to segment 3 by an angle of -45 °, and the intersection of the axes coincides with the point E ₂ , which ensures smooth conjugation with segment 3.

The section of the tooth profile of the driving rotor is made according to the curve of the running-in tooth of the driving rotor along the tooth profile of the driven rotor. So, the profile of the back side of the tooth of the driving rotor has the following sections (Fig. 3): section A ₁ E _{1 is} made along the envelope of section F ₂ E _{2 of the} second Bernoulli lemniscate; section E ₁ G _{1 is} made along the envelope of segment E ₂ G ₂ , section G ₁ H _{1 is} made along the envelope of section G ₂ H _{2 of the} first Bernoulli lemniscate.

In addition, in an embodiment, the profile of the rear part of the cavity of the driven rotor along the rotation can be described by the following curves: epicycloid 1 and two Bernoulli lemniscates, the sections of the loops of which are mated directly so that the data centers of the lemniscate Bernoulli coincide, and the tangent to the lemniscates of Bernoulli at the point of their conjugation with each other passes through the axis of rotation of the driven rotor.

Due to such formation of tooth profiles with a smaller pressure angle, which reduces energy loss at the contact point, and a reduced area of a triangular gap, which reduces flow between compression cavities, an increase in machine efficiency is provided.

Claims (5)

1. Toothed engagement of a screw machine with an asymmetric tooth profile of the driving and driven rotors, in which the back profile along the rotation of the cavity, which is the tooth profile of the driven rotor tooth, smoothly mates with its outer circumference, and the corresponding tooth profile section of the driving rotor is made according to the running-in curve the tooth of the driving rotor along the tooth profile of the driven rotor, and the profile curve of the rear part of the cavity of the driven rotor along the rotation of the initial circle is an elongated epicycloid, about developed by the rolling curve of the top of the tooth of the driving rotor, characterized in that the conjugation of the back profile along the rotation of the cavity part of the driven rotor with the outer circumference is made through mutually connected sections of the Bernoulli lemniscate loops, one of which is connected with the outer circumference of the driven rotor, and the other with elongated epicycloid. 2. The meshing according to claim 1, characterized in that the conjugation of sections of the lemniscate Bernoulli loops is performed by means of a straight line segment whose ends lie on the centers of the corresponding lemniscate Bernoulli. 3. The meshing according to claim 1, characterized in that the sections of the corresponding loops of the corresponding Bernoulli lemniscates are conjugated directly, while the centers of the Bernoulli lemniscates coincide. 4. The meshing according to claim 2, characterized in that the straight segment lies on a straight line passing through the axis of rotation of the driven rotor. 5. The meshing according to claim 3, characterized in that the tangent to the Bernoulli lemniscates at the point of their conjugation with each other passes through the axis of rotation of the driven rotor.

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