RU2767416C1 - Rotary volumetric machine - Google Patents

Abstract

FIELD: machine building.

SUBSTANCE: invention relates to design of rotary volumetric machines - compressors, hydraulic pumps, pneumatic motors, hydraulic motors, in which working medium moves through chambers of variable volume formed by cavity and piston. Rotary volumetric machine is made on the basis of gear pump with internal gearing with ratio of teeth numbers 1:2. Engaged teeth form variable-volume chambers with zero stray volume at displacement of working medium. Contours of bypass openings 11 along one of the working medium inlet or outlet channels are made with overlapping only those contours of interdental cavities of external rotor 2 on its end planes for any of its positions, which are closed by teeth of internal rotor 3 to form chambers of variable volume. Inner space of outer rotor 2 can be filled with working medium.

EFFECT: invention is aimed at ensuring applicability of a rotary volumetric machine for a compressible working medium, reducing friction, increasing efficiency of the machine, simplifying the design and increasing its service life.

8 cl, 5 dwg

Description

The technical solution relates to the design of rotary volumetric machines - compressors, hydraulic pumps, pneumatic motors, hydraulic motors, in which the working medium moves through chambers of variable volume formed by a cavity and a piston.

Various designs of rotary volumetric machines are widely known, where in the housing between two parallel walls there are an external rotor interacting with each other with internal teeth and an internal rotor of smaller diameter with external teeth located to it with eccentricity.

The closest analogue adopted for the prototype is US patent 3810721, which describes a variant of a rotary machine containing a housing with a cylindrical cavity, closed by the corresponding end walls, with an external rotor with internal teeth located in the internal volume of the housing and, installed inside it with eccentricity, an internal rotor with external teeth with the possibility of rotation; the ratio of the diameters of the pitch circles of the gearing of the inner and outer rotors is 1:2; the lateral surfaces of the teeth of the inner rotor, with which they interact with the lateral surfaces of the teeth of the outer rotor, are made by the surfaces of straight circular cylinders, the axes of which are located on the initial circle of the gearing, the tops of the teeth are cut off relative to the cylindrical surface, and their shape is not tied to the shape of the bottom surface of the interdental cavities of the outer rotor; interdental cavities of the outer rotor have bottom surfaces and flat side surfaces; the inner space of the outer rotor contains a central fixed body with sliding surfaces of the tops of the teeth of both rotors; the inner rotor is cantilevered on the drive shaft; bypass inlet and outlet windows for the working medium are made in the end walls and in the control plate installed in one of the side walls, and the contours of the bypass windows on the inlet and outlet channels of the working medium connect the interdental cavities of the outer rotor, closed by the teeth of the inner rotor with unclosed cavities, and the differential pressure of the working medium is maintained by the central body.

In the specified prototype, with the apparent similarity of the entry of the tooth of the inner rotor into the interdental cavity of the outer rotor with the “piston-cylinder” scheme, the contours of the bypass windows are made for the scheme of operation without squeezing the working medium exclusively by the piston tooth and correspond to the principles of constructing an internal gear pump, which carries out the working process by transferring fluid by interdental cavities, followed by partial displacement of fluid from these cavities by the volume of the teeth; chambers of variable volume formed by the interdental cavities of the outer rotor, which are closed by the teeth of the inner rotor, are open at the same time along the end planes and communicate with the unclosed cavities. Such a machine requires a central body. The pressure drop of the working medium is supported by a conditionally backlash-free sliding of the tops of the teeth along the central fixed body, side walls, and backlash-free contact in the gearing. Thus, the shape of the tops of the teeth of the inner rotor and the shape of the bottom surface of the cavities of the interdental space of the outer rotor are not of fundamental importance for the operation of the prototype. Conventional involute gear pumps work on the same principle. Such a machine is not suitable for a compressible working medium due to the presence of parasitic volume in the cavities formed by the teeth of the rotors, and cannot be used to compress the working medium. In addition, between the outer and inner rotors, as with any gear pump with internal gearing, there are contact stresses caused by the pressure drop of the working medium. The same pressure drop causes axial forces on the rotors from the difference in bypass windows at the opposite ends of the rotors, which, in turn, cause additional friction forces of the rotors against the end wall and the control plate. The friction in the gearing, the friction of the ends of the rotors with the side wall and the control plate, the tops of the teeth with the central body, reduces the efficiency and resource of the rotary machine in the prototype version, and the central core complicates its design.

The common essential features of the prototype, coinciding with the essential features of the proposed technical solution, are the following: a rotary volumetric machine containing a body with a cylindrical cavity, closed by the corresponding end walls with bypass windows, with an external rotor with internal teeth located in the internal volume of the body and installed inside it with eccentricity, internal rotor with external teeth rotatable; the ratio of the diameters of the pitch circles of the gearing of the inner and outer rotors is 1:2; the lateral surfaces of the teeth of the inner rotor, with which they interact with the lateral surfaces of the teeth of the outer rotor, are the surfaces of straight circular cylinders, the axes of which are located on the pitch circle of the gearing; interdental cavities of the outer rotor have bottom surfaces and flat side surfaces; the inner rotor is fixed on the drive shaft.

The technical problems that the proposed device is aimed at solving are the following: the presence of a parasitic volume in the interdental cavity of the outer rotor, closed by the tooth of the inner rotor, in the “dead center” position, when the tooth of the inner rotor is maximally immersed in this cavity, the inapplicability of a rotary volumetric machine for compressible working environment; high friction between the rotors, between the rotors and the walls, caused by their force interaction; low efficiency of the machine; the complexity of the design, its small resource.

To solve these technical problems in a rotary volumetric machine containing a body with a cylindrical cavity, closed by the corresponding end walls with bypass windows, with an external rotor with internal teeth located in the internal volume of the body and, installed inside it with eccentricity, an internal rotor with external teeth with the possibility rotation; the ratio of the diameters of the pitch circles of the gearing of the inner and outer rotors is 1:2; the lateral surfaces of the teeth of the inner rotor, with which they interact with the lateral surfaces of the teeth of the outer rotor, are the surfaces of straight circular cylinders, the axes of which are located on the pitch circle of the gearing; interdental cavities of the outer rotor have bottom surfaces and flat side surfaces; the inner rotor is fixed on the drive shaft, unlike the prototype, the surfaces of the tops of the teeth of the inner rotor are made as a continuation of the side cylindrical surfaces of the teeth (the tops are cut in the prototype); the bottom surfaces of the interdental cavities of the outer rotor are made cylindrical along a radius conjugated with the cylindrical surfaces of the teeth of the inner rotor with axes located on the pitch circle of the gearing of the outer rotor; the inner space of the outer rotor is made with the possibility of filling the working medium (in the prototype, the inner space of the outer rotor is filled with a central fixed body with the sliding surfaces of the tops of the teeth of both rotors), and the contours of the bypass windows along one of the channels of the inlet or outlet of the working medium are made with overlapping only those contours of the interdental cavities of the outer rotor on its end planes for any of its positions, which are closed by the teeth of the inner rotor to form chambers of variable volume.

Additionally, the teeth of the outer rotor can be made with a maximum height by extending the flat side surfaces until they intersect with the constructive rounding of the tops of the teeth, which ensures maximum immersion of the tooth of the inner rotor in the interdental cavity of the outer rotor, increases the working volume of the rotary machine.

Additionally, the contours of the bypass windows on opposite sides of the rotors can be made mirror, which balances the pressure forces of the working medium in the axial direction.

Additionally, the inner and outer rotors can be connected to each other by a synchronizing gear, which allows the operation of the rotary machine without lubrication in the working area.

Additionally, the inner and outer rotors can be made double-bearing, which increases reliability and service life (in the prototype, the inner rotor is cantilevered on the shaft).

Thanks to the presence of these distinctive features, the following technical results are achieved:

1. When the teeth of the inner rotor are round-cylindrical, including the tops of the teeth, with the corresponding mating design of the outer rotor, there are no parasitic volumes of variable volume chambers, which is important for compressors and vacuum pumps, and, in general, applicability for a compressible working medium. Piston round cylinders are technologically simpler in manufacture and can be manufactured separately from the inner rotor hub with their own requirements for the properties of the friction surface. The execution of the bypass windows of the inlet or outlet channel, in which the windows open at any position of the rotors only for the interdental cavities of the outer rotor closed by the teeth of the inner rotor, the working process fundamentally changes, in which the pressure drop of the working medium is formed only in the chambers of variable volume of the interdental cavities, and turns out to be not needed central body.

2. The torque during the operation of the rotary machine acts only on the inner rotor, and on the outer rotor no torque occurs from the pressure of the working medium, therefore there is no power contact between the rotors, which is directly related to the pressure drop of the working medium, but there is only a contact force caused by resistance to rotation of the outer rotor, if it is made freely rotating, from gas or hydrodynamic friction with the end walls and from friction-rolling bearings, which is relatively small.

3. Variable volume chambers have the largest possible working volume for the available dimensions of the rotary machine and, therefore, give maximum productivity.

4. The absence of a fixed central body (which is in the prototype) simplifies the design, respectively, the losses due to sliding friction are reduced. The friction of the rotors on the end walls is also reduced due to the mirroring of the bypass windows on the sides opposite from the rotors and, in fact, is reduced to gas or hydrodynamic friction due to the balancing of the pressure forces of the working medium on the rotors in the axial direction. All this increases efficiency and resource.

5. When working with an additional synchronizing gear, the teeth of the rotors will not have force interaction with each other, and to eliminate gaps, the teeth can be made with an elastic or running-in surface, or some gap can be allowed in the mesh and lubrication in the mesh of the rotors is not required. The gap in the teeth of the rotors leads to losses in efficiency, but with an increase in the size of the rotary machine and the speed of rotation of the rotors, the percentage of losses decreases. Therefore, the scheme with an additional gear transmission is appropriate for large-sized high-speed rotary machines and, among other things, as an alternative to bladed turbines, which has a higher efficiency than that of bladed turbines and an incomparably lower cost.

6. Both rotors can be made double-bearing, which increases reliability and service life (in the prototype, the inner rotor is cantilevered on the shaft).

The advantages mentioned above make it possible to obtain high specific power characteristics due to high pressures and high rotational speeds. Structurally and technologically, the rotary machine according to this invention is extremely simple. For example, both rotors and housing can be extruded from metal or molded from plastic. Large-sized rotors can be made welded and hollow from sheet material. The number of parts is minimal.

The proposed technical solution can be used in the design of liquid pumps and hydraulic motors, compressors and vacuum pumps, pneumatic, gas and steam rotary machines.

There is a valid sample of the proposed rotary machine.

The described device is illustrated by the drawings of Fig. 1-5. The figures show a version of the rotary machine, which is implemented in a prototype. At the same time, in this embodiment, to reduce gas- or hydrodynamic friction, the contact area of the end surfaces of the rotors to the end walls is reduced to a contour covering the contours of the interdental cavities of the outer rotor, when these cavities are closed by the teeth of the inner rotor, and outside this contour, the rotors have a gap with the end walls . The contour reduction in this case is implemented in the form of overlay plates, which are structural elements of the end walls. This option is technologically simpler and allows the use of a different material, for example, with antifriction properties. Reducing the contour can also be implemented in the form of local thickening of the end walls, which is less technologically advanced. As a simplified version of manufacturing, having more friction, the end walls of the outer rotor can be made flat. Fasteners and seals are not shown in the illustrations.

In Fig. 1 shows a section of a rotary three-dimensional machine with a conditionally removed end wall, but with an overlay plate left.

In the drawings of FIG. 2 and FIG. Fig. 3 shows images of a rotary machine with the end wall removed in two positions of the rotors, showing only those details that are necessary to explain its operation: Fig. 2 shows the absence of parasitic volume when the working medium is expelled, and FIG. 3 - processes of suction or displacement of the working medium in chambers of variable volume.

In Fig. 4 shows a section along the plane of the axis of rotation of a rotary volumetric machine. The figure shows that the surface of the end walls adjoins the end surfaces of the rotors only through the overlay plates of the end walls, and outside the plates, the end walls have a gap with the rotors.

In Fig. 5 shows a variant of a rotary volumetric machine with synchronization of the rotors by an additional gear.

Shown in FIG. 1-5 rotary positive displacement machine, contains:

1 - housing with a cylindrical cavity;

2 - outer rotor;

3 - inner rotor;

4 - end walls;

5 - patch plates of the end walls, which are a structural element of the end walls and can be made both overlaid and merged with the end walls. Their area of contact with the ends of the rotors is reduced to a contour covering, along one of the channels of the working medium, the contours of the interdental cavities of the outer rotor, when these cavities are closed by the teeth of the inner rotor. Through the specified channel, each interdental cavity of the outer rotor during rotation opens from the ends with bypass windows in the overlay plates 12, and through the other channel - along the entire end plane of the rotors outside the contour of the overlay plates. Overhead plates can be made without reducing the contact surface with the ends of the rotors.

6 - shaft of the inner rotor;

7 - spacer ring of bearings;

8, 9 - bearings of the inner and outer rotors, respectively.

The two-bearing installation of rotors on bearings, in comparison with the cantilever installation, has an advantage in terms of rigidity and resource of the rotary machine;

10 - bearing caps;

11 - bypass windows for the input of the working medium for the compressor mode, supercharger (clockwise rotation) or output for the engine mode (counterclockwise rotation);

12 - bypass windows in the plates of the end walls for the output of the working medium in the compressor mode or the input in the engine mode;

13 - chamber of variable volume;

14 - rounding the tops of the teeth of the outer rotor when making the teeth with a maximum height by extending the flat side surfaces until they intersect;

15 - bypass windows for the working medium in the end walls, forming a single structural element with the bypass windows of the plates.

16 - shaft of additional gearing;

17, 18, 19 - additional gear wheels (the ring gear of the outer rotor is invisible);

20 - pipelines for the working environment.

For a better understanding, in Fig. 2 the image is given without one of the overlay plates 5 located on the front in the image of the end plane of the rotors, the rotors are shown in the position of complete displacement of the working medium through one of the chambers of variable volume, and in Fig. 3 shows the opening of individual chambers to the corresponding channels of the working medium: the chamber in which suction takes place opens towards the inlet channel, and the chamber in which displacement occurs opens towards the outlet channel.

The rotary volumetric machine in the mode of a compressor, or a supercharger, or a vacuum pump rotates in the direction of the arrow "Supercharger" and works as follows: the working medium, in the general case, compressible, enters the cavity formed by rotors 2 and 3, housing 1, end walls 4 through bypass windows 11 from the atmosphere or through pipelines from any volume. During the rotation of the rotors 2 and 3, the teeth of the inner rotor 3 sequentially close the working medium in the chambers of variable volume 13, formed by the teeth of the inner 3 and outer 2 rotors, overlay plates 5, then compress the working medium to the degree of compression specified by the geometry of the bypass windows 12 (image of Fig. 2) , and displace it through the bypass windows 12 (the image of Fig. 3) and then through the bypass windows 15 into the discharge channel. When the teeth of the inner rotor 3 pass through the position of the rotors with the maximum immersion of the tooth of the inner rotor into the interdental cavity of the outer rotor (image of Fig. 2) - zero chamber volume, the contour of the interdental cavity of the outer rotor leaves the bypass window 12, goes beyond the contour of the overlay plate 5, and this the cavity again begins to be filled with the working medium from the cavity formed by the rotors 2 and 3, the housing 1 and the end walls 4 through the end planes of the rotors (image of Fig. 3).

In the engine mode, the working medium under pressure is supplied through the bypass windows of the plates 12, expands in the chambers 13 when the rotors rotate in the direction of the arrow "Engine" of Fig. 2 and, after opening the chambers, exits through the bypass windows 11. In the variant with an additional gear for synchronizing the rotors 2 and 3, the operating torque can be applied to the shaft 16 of the additional gear.

Claims (8)

1. Rotary volumetric machine, containing a body with a cylindrical cavity, closed by the corresponding end walls with bypass windows, with an external rotor with internal teeth located in the internal volume of the body and an internal rotor with external teeth installed with eccentricity inside it with the possibility of rotation, the ratio of the diameters of the initial circles gearing of the inner and outer rotors is 1:2, the lateral surfaces of the teeth of the inner rotor, with which they interact with the lateral surfaces of the teeth of the outer rotor, are the surfaces of straight circular cylinders, the axes of which are located on the pitch circle of the gearing, the interdental cavities of the outer rotor have bottom surfaces and flat side surfaces, the inner rotor is fixed on the drive shaft, characterized in that the surfaces of the tops of the teeth of the inner rotor are made as a continuation of the side cylindrical surfaces of the teeth, the bottom surfaces of the interdental cavities of the outer rotor are made cylindrical along the radius conjugated with the cylindrical surfaces of the teeth of the inner rotor with the axes located on the initial circle of the gearing of the outer rotor, the internal space of the outer rotor is made with the possibility of filling the working medium, and the contours of the bypass windows along one of the channels for inlet or outlet of the working medium are made with overlapping only those contours of the interdental cavities of the outer rotor on its end planes for any of its positions, which are closed by the teeth of the inner rotor to form chambers of variable volume. 2. The machine according to claim 1, characterized in that the teeth of the outer rotor are made with a maximum height by extending the flat side surfaces until they intersect with a constructive rounding of the tops of the teeth to ensure maximum immersion of the tooth of the inner rotor into the interdental cavity of the outer rotor. 3. The machine according to any one of paragraphs. 1, 2, characterized in that the contours of the bypass windows on opposite sides of the rotors are mirrored. 4. Machine according to any one of paragraphs. 1, 2, characterized in that the inner and outer rotors are connected by a synchronizing gear. 5. The machine according to claim 3, characterized in that the inner and outer rotors are connected by a synchronizing gear. 6. Machine according to any one of paragraphs. 1, 2, 5, characterized in that the inner and outer rotors are double-supported. 7. The machine according to claim 3, characterized in that the inner and outer rotors are double-supported. 8. The machine according to claim 4, characterized in that the inner and outer rotors are double-supported.

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