RU2304736C1 - Screw gear - Google Patents

Abstract

FIELD: mechanical engineering.

SUBSTANCE: screw gear comprises shell whose inner side is provided with one screw, face lids, and one rotor whose outer side is also provided with one screw. The teeth of the shell screws and rotor tightly engage each other. One of the screws is used for transmitting torque and has convex teeth, and the other screw receives only a small part of the total torque and has concave teeth. The insert is interposed between the screws of the rotor and shell and defines inner spaces together with the face lids and hollows between the teeth of the screws. The face lids are provided with high-pressure passages and with one low-pressure passage. The seals are interposed between the face lids and rotor and between face lids and shell from the side of low-pressure and high-pressure ports.

EFFECT: enhanced reliability and efficiency.

2 cl, 9 dwg

Description

The invention relates to the field of mechanical engineering, in particular to volumetric rotary machines, and is intended both to convert the pressure energy of gases, vapors or the gas phase of a gas-liquid medium into the mechanical energy of rotation of the output shaft, and to compress gases, vapors or the gas phase of a gas-liquid medium, and also for use in vacuum technology as a vacuum pump, etc.

The prior art rotary machine (RU 2187703 C2 from 08.20.2002), comprising a housing, a rotor with blades, inter-roller chambers and synchronizing gears. The rotor is made in the form of a cylindrical shell with blades on the inner surface. End caps are provided, one of which is pressed onto the shaft of the rotary machine, and the other rests on the bearing. Inside the shell there is a core with samples for placement of separator rollers, bearings, synchronizing gear shafts, input and output channels of the working medium. Inter-roller chambers are formed between the core, the shell and the separator rollers. One of the end caps is made in the form of a rotor wheel of a radial type, and the core is pressed onto the central fixed rod. One part of the rod is hollow, and the hollow end of the rod is fixed in the end cap of the rotary machine. The other, a solid end, rests in another end cap on a bearing located inside the hollow shaft. In the hollow part of the rod, pressed into the core, samples are made connecting the inner cavity of the central rod with channels for outputting the working medium from the inter-roller chambers, while the hollow part of the rod is a channel for removing the working medium from the rotor machine.

A disadvantage of the known technical solution is that the compression in the cavities formed by the working elements is not the same, which leads to a loss of power, and the presence of large dead space reduces the flow of the rotary machine.

The rotary compressor known from the prior art (RU 2064091 C1 of 07.20.1996) comprises a housing with a cylindrical cavity, longitudinal partitions and input and output windows. The rotor consists of an output shaft, pylons, a support shaft and disk-shaped walls. Pistons are located between the disk-shaped walls in the longitudinal recesses of the pylons and have longitudinal recesses and a mechanism for synchronizing the rotation of the pistons and shaft, made in the form of a gear system. The working volumes are formed by the outer cylindrical surfaces of the pylons, the inner surface of the housing, as well as the end surfaces of the disk-shaped walls. Bypass channels are made in the walls, and a gap is made between the edges and the inner surface of the piston longitudinal recesses and the longitudinal partitions.

A disadvantage of the known technical solution is that the compression in the cavities formed by the disk-shaped walls in the longitudinal recesses of the pylons and the longitudinal recess of the rotor, as well as the cylindrical surface of the casing, the outer cylindrical surfaces of the pylons and the longitudinal partition-gate, is not the same, the shape of the windows is not optimal, which together leads to power loss and reduces compressor flow.

Known biotative trochoidal (gerotor) machine with internal gearing of rotors (SU 673745 A1 from 07/15/1979), comprising a housing, input and output channels, a jumper with a given width, internal and external gears. This machine is designed to operate as a compressor, expander, pump in the oil and gas industry.

A disadvantage of the known technical solution, which is also inherent in all known technical solutions of machines with internal gearing, is that the conjugated pairs of the rotor and the shell are equal in them, since the gas forces acting on them create on average the same rotational moment, and, accordingly, the purpose of the drive or the slave link is determined only by the conditions of their operation.

As the closest analogue of the patented embodiment, a screw machine is adopted, comprising: a housing, rotors, thrust and thrust bearings, seals. Screws are cut on the middle thickened part of the rotors. The rotation of the rotors of the screws is synchronized by gears sitting on the shafts of the rotors. The screws are helical helical large-modular gears with profile teeth. The teeth of each screw in the section with a plane perpendicular to the axis of rotation of the screw (end plane) are outlined by complex curves forming the profile of the teeth. The profiles of the teeth of the twin screws are selected in such a way that with the mutual rolling of the screws, their teeth mate theoretically gapless. Typically, a screw machine contains two screws (rotors). One of them - the leader, is used to transmit torque. It has convex, wide teeth. Another driven screw - has concave and thin teeth. The driven screw perceives only a small fraction of the total torque. Therefore, the gears connecting the screws also transmit only a small part of the total torque of the machine. The low pressure window is in the form of approximately two contacting open annular sectors. It is located at the end of the screws and sometimes comes in a small area and on the side surface. The high-pressure window, as a rule, is located both on the side and from the end of the screws. Part of the windows in the end plane has a shape that copies the end profile of the screws, and therefore this window shape depends on the tooth profile. In screw machines working with oil supply to the working space, the teeth can be in contact with each other, if this allows the nature of the touch of the side profiles of the teeth, and then synchronizing gears on the rotors may be absent. Screw machines working with the supply of lubricant to the workspace are called oil-filled.

The disadvantages of the known technical solutions include the fact that the known screw machines have large dimensions and weight than rotary machines with internal gearing.

The problem to which the present invention is directed, is the elimination of the above disadvantages, the creation of a screw machine with the best specific volumetric and mass indicators among the known screw machines, as well as expanding the scope of its application.

As a technical result from the implementation of this invention, it is possible to note an improvement in specific volumetric and mass indicators, an increase in reliability and a service life, as well as an increase in the efficiency of the device.

Taking into account the relative complexity of the allocation and separation of essential features in solving the problem and the accuracy of its presentation, the claims will be made without separation into distinctive and restrictive parts.

The specified technical result is achieved due to the fact that the present invention contains a shell on the inside of which at least one screw is cut, end caps and at least one rotor, on the outside of which is cut at least one screw . The corresponding profiles of the teeth of the screws of the shell and the rotor during their mutual running in are theoretically gapless for most of the engagement. One of the screws is used to transmit torque and has convex teeth, while the other screw perceives only a small fraction of the total torque and has concave teeth. An insert is installed between the rotor and shell screws, which together with the end caps and cavities between the teeth of the screws serves to create internal working cavities. At least one channel of "high" pressure and at least one channel of "low" pressure are made in the end caps, both on flat, transverse axis of the rotor, surfaces of the end caps, and on the longitudinal cylindrical surfaces of the end caps, and also on the surfaces of the insert adjacent to the rotor and shell screws. Seals are installed between the end caps and the rotor, as well as between the end caps and the shell on the sides of the "low" and "high" pressure windows, with the possibility of preventing oil from entering the working cavities and the working fluid in the oil system. A safe clearance between the mating surfaces of the rotor and shell screws is provided by at least one synchronizing gear and thrust and / or thrust bearings of rolling and / or sliding.

In addition, an embodiment of the invention is possible in which there is no synchronization gear and the teeth of the mating screws are in contact. In this case, oil is supplied to the working space of the machine.

When constructing screw pair profiles in the perpendicular section plane to the rotor axis, piecewise continuous curves are used that can be described by trochoid, circles, ellipses and other curves that can be connected by straight sections, and the corresponding curves on the conjugated profile are their envelopes. The convex profile of the teeth in the transverse plane of the cross section of the screws is the "leading", and the concave - "slave".

The working cavities in the machine are created by the hollows between the teeth of the screws and the adjacent walls of the insert and the end caps.

The geometric degree of compression or expansion of the working fluid is determined by the shape of the windows, and in this case, as a rule, the total area of the window of "low" pressure is greater than the total area of the window of "high" pressure.

These signs are essential and interconnected causal relationship with the formation of a set of essential features sufficient to achieve the specified technical result. In this case, the "absence" of force interaction between the leading and the driven working links is one of the most important advantages of the present invention, in comparison with the known rotary machines of volume type. Synchronization gears operate with lower forces that are constant in direction. Due to this, in a screw machine, “backlashless” (with minimal clearances) gears, synchronizing gears are used, which provide more accurate synchronization of the rotation of the moving links (rotor and casing) among known machines with internal gearing and allow them to be guided by the smallest working clearances between the profile the surfaces of the moving links among machines with internal gearing, and therefore, have higher economic performance.

Further, the invention will be disclosed in more detail, with reference to graphic materials on which:

figure 1 is a schematic diagram of the invention with a synchronizing gear and one rotor, the screw of which has a "leading" tooth profile;

figure 2 is a schematic diagram of the invention with a synchronizing gear and one rotor, the screw of which has a "driven" tooth profile;

figure 3 is a schematic diagram of the invention with a synchronizing transmission and several rotors, the screws of which have a "driven" tooth profile;

figure 4 is a schematic diagram of the invention without a synchronizing transmission, with several rotors, the screws of which have a "driven" tooth profile;

figure 5 - embodiments of the windows "high" and "low" pressure;

6 - embodiments of the invention with various leading links;

Fig.7 - Fig.9 - options for constructing window profiles of "high" and "low" pressure.

The present invention is illustrated by a specific implementation example, which, however, is not the only possible, but clearly demonstrates the possibility of achieving the above set of features of a technical result.

According to the invention, the proposed device comprises: a shell 8, on the inside of which at least one screw (helical helical gear) is cut, end caps 14 and at least one rotor 7, on which at least one screw is cut (helical helical gear). The corresponding profiles of the teeth of the screws of the shell 8 and the rotor 7 during their mutual running in are theoretically gapless for most of the engagement, while one of the screws is used to transmit torque and has convex teeth, and the other screw receives only a small fraction of the total torque and has concave teeth . An insert 1 is installed between the screws of the rotor 7 and the shell 8, which together with the end caps 14 and the cavities between the teeth of the screws of the rotor 7 and the shell 8 serves to create internal working cavities in the machine. At least one channel of the "high" pressure 3 and at least one channel of the "low" pressure 4 are made in the end caps 14, both on the plane, transverse to the axis of the rotor surfaces of the end caps 14, and on the longitudinal cylindrical the surfaces of the end caps 14, as well as on the surfaces of the insert 1, adjacent to the screws of the rotor 7 and the shell 8. To prevent oil from entering the working cavities and the working fluid in the oil system, seals 12 and 13 are installed, at least between the end caps 14 and the rotor 7 as well as between the end faces to yshkami 14 and the shell sides with a "low" and "high" pressure. A safe clearance between the mating surfaces of the screws of the rotor 7 and the shell 8 is provided by at least one synchronizing gear 9 and thrust and / or thrust bearings (rolling and / or sliding) 10 and 11.

Figure 6 shows single-rotor embodiments of the invention in which the transmission of torque is carried out: firstly and secondly, from the rotor 7 - Fig.6 (a) and (b); thirdly, from the shell 8 - Fig.6 (c); fourthly, from insert 1 - Fig.6 (g).

The rotors in the embodiments of the invention shown in FIGS. 6 (a) and (b) have a “leading” tooth profile, and FIGS. 6 (c) and (d) have a “driven” profile.

Moreover, in the embodiment shown in Fig. 6 (d), insert 1 is a carrier, and on the non-core part of the shell 8 there are channels of "high" and "low" pressure 3 and 4 for supplying and discharging the working fluid to windows 5 and 6. In the embodiment of the invention shown in Fig. 6 (a), the rotational moment is supplied (withdrawn) from the rotor 7, and the insert (carrier) 1 together with the stationary shell 8 create working volumes.

In the embodiment, when the number of teeth of the rotor 7 is one less than the number of teeth of the shell 8, insert 1 may be absent - the gerotor version of the screw machine.

A multi-rotor embodiment of the invention is obtained from a single-rotor one due to a change in the gear ratio between the rotor and shell screws so that when the required number of rotors engaged with the shell screw are placed inside the shell, their circumferences of the outer diameters do not intersect each other.

Windows 5 and 6 can be built (see Fig.7-9): first, on the end caps 14 in transverse planes adjacent to the screws (5.1 and 6.1), and secondly, on the longitudinal surfaces of the insert 1 (5.2 and 6.2 ), and thirdly, on the longitudinal cylindrical surfaces of the end caps (5.3 and 6.3). Moreover, depending on the tasks to be solved, each window may represent a different combination of these sub-options. Moreover, they are usually constructed in such a way that during the operation of the invention, the cutting or opening of the message of the working cavities with the corresponding channels 3 or 4 is carried out simultaneously.

Theoretical window profiles 5.1 and 6.1 (see Fig. 7) in the transverse plane are formed by: arcs AB and CD of the circumferences of the legs and head of the teeth of the shell; arcs DE and FG of the circumference of the legs and heads of the teeth of the rotor; aircraft shell tooth profile; rotor tooth profile EF; line of engagement AG. In real window profiles 5.1 and 6.1, angles A, B, C, E, F and G, as well as angles not shown on the engagement line, are smoothed out by smooth curves. In addition, the region of the end cover 14, outlined by arcs DCD 'and D'ED, can be assigned to the windows, and the connection of the insert 1 and the end caps 14 in this case is performed through the contact areas 15 located within the boundaries of the DCD'ED and selected based on specific machine design requirements.

Window profiles 5.2 and 6.2 (see Fig. 9) are formed by helical lines KL and MN, similar to the corresponding helical lines of the tops of the teeth of the rotor 7 and the shell 8.

For the manufacture of windows 5.3 and 6.3, it is necessary that the profile of the shell screw has a section formed by the circumference of the inner diameter of the cavity, and at the same time, the part of the shell 8 from the end of the side on which this window is built should be bored to the circumference of the cavity of its teeth, i.e., until the shell of the screw slots. The end cover 14, on the contrary, is made with a cylindrical protrusion, the inner diameter of which is equal to the diameter of the circumference of the cavity of the teeth of the shell 8, so as to fill the resulting cylindrical bore of the shell. A window is made on this cylindrical protrusion of the end cover, one side of which is bounded by direct contact of the cylinder of the outer circumference of the rotor teeth and the cylinder of the inner circumference of the shell teeth (line AH), the other side coincides with the helical line formed by the edge of the shell foot of the shell when the window is cut off (BH line) and the third - the transverse edge of the shell screw (line AB). In this case, the longitudinal size of the formed triangular window can be truncated (line H'H ").

Windows 5.3 and 6.3 may not be connected with the end caps 14, located on the outside of the shell 8.

The method for constructing windows 5 and 6 described above provides the least hydraulic resistance to the flow of the working fluid and, therefore, provides a more economical mode of operation of the machine.

Figure 1-4 shows possible examples of single-rotor and multi-rotor machines.

In the one-rotor embodiment of the invention shown in FIG. 1, the rotor 7 is driving and is used to transmit torque. A safe gap between the screws of the rotor 7 and the shell 8 is provided by a synchronizing gear 9 (figure 1). The rotating shell 8 and other elements in it are closed by a composite casing 2, in which openings are made for the channels of "high" and "low" pressure.

In a one-rotor embodiment of the invention shown in FIG. 2, the leading is a shell 8, which is used to transmit torque. A safe gap between the screws of the rotor 7 and the shell 8 in it is also provided by a synchronizing gear 9 (figure 2).

The embodiment of the invention shown in FIGS. 3 and 4 contains four driven rotors, and the torque is transmitted from the carrier formed by the insert 1 and the end caps 14 of the above machine, which can be performed at the same time. The screws of the rotors 7 are mounted on the axles 16. The shell 8 does not rotate and together with the covers 17 of the casing 2 supports the axis of the carrier 1. In the example shown in Fig. 4, there are no synchronizing gears 9, so oil should be supplied inside the machine.

The invention can be used both for compression of gases, vapors or the gas phase of a gas-liquid medium (working fluid), and for its expansion.

The compression of the working fluid according to the proposed design of the present invention is as follows. The screws 7 and 8, rotating relative to each other, starting from the suction end ("low" pressure), free the cavities between the teeth. These cavities (hereinafter referred to as cavities), due to the discharge created in them, are filled with a working fluid entering through the “low” pressure window 6. At the moment when the cavities reach, for example, the maximum value, having passed through window 6, they are disconnected from the supply channel of the "low" pressure 4. Thus, the volumes filled with the working fluid and limited by the surfaces of the screws, end caps, and inserts are disconnected from channel 4 through which the working fluid was supplied, but have not yet connected to channel 3, through which it is discharged from the machine. As the tooth of the driven screw enters the cavity of the lead, the volume occupied by the working fluid decreases, and the working fluid is compressed. After a certain angle of rotation of the lead and driven screws, their cavities are interconnected, forming one common paired cavity. Then the tooth of the lead screw begins to fill the cavity of the follower, which leads to a more intense compression of the gas in the paired cavity. The process of compressing the working fluid in the paired cavity continues until all its decreasing volume with the compressed working fluid reaches the edge of the injection window 5 (“high” pressure). At this point, the internal compression process in the compressor ends. With further rotation of the screws 7 and 8, after the pair cavity is connected to the injection channel 3 (high pressure), the process of expelling the working fluid occurs.

With the expansion of the working fluid, the present invention works exactly the opposite.

All structural elements of the present invention can be made of various types of materials: plastic, metal, ceramics, etc., and also to provide the desired properties, such as heat resistance, hardness, etc., appropriate coatings can be applied to them.

The invention meets the condition of patentability "industrial applicability", since it is feasible using known means of production.

Claims (3)

1. A helical gear, preferably for a helical machine with internal gearing, comprising a shell on the inside of which at least one screw is cut, end caps and at least one rotor, on the outside of which is cut at least one screw, while one of the said screws is used to transmit torque and has convex teeth, and the other screw takes only a small fraction of the total torque and has concave teeth, an insert is installed between the rotor and shell screws, which a place with end caps and cavities between the teeth of the screws serves to create internal working cavities, at least one high-pressure channel and at least one low-pressure channel are made in the end caps, both on flat, transverse to the rotor axis, end surfaces covers, and on the longitudinal cylindrical surfaces of the end caps, as well as on the surfaces of the insert adjacent to the screws of the rotor and the shell, while at least between the end caps and the rotor, as well as between the end caps and the shell minutes with side windows low and high pressure seal mounted, with the possibility of preventing contact of oil in the working chamber and the working fluid in the oil system. 2. The helical gear according to claim 1, characterized in that the safe gap between the mating surfaces of the rotor and shell screws is provided by at least one synchronizing gear and thrust and / or thrust bearings of rolling and / or sliding. 3. The helical gear according to claim 1, characterized in that in the case of oil supply to the working space of the machine, there is no synchronizing gear, and the teeth of the mating screws are in contact.

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