WO2023237955A1

WO2023237955A1 - Housing for housing a gearbox of a rotary screw compressor.

Info

Publication number: WO2023237955A1
Application number: PCT/IB2023/055340
Authority: WO
Inventors: Taici BOTELHO; Mahesh RATNAPARKHI
Original assignee: Atlas Copco Airpower, Naamloze Vennootschap
Priority date: 2022-06-09
Filing date: 2023-05-24
Publication date: 2023-12-14

Abstract

According to an embodiment, the invention comprises a beam-shaped housing (100) for housing a system for transmitting a torque from a drive shaft of a motor to rotor shafts of a rotary screw compressor, the housing (100) comprising a motor opening (104) on a first side (102), and two screw openings (202, 203) on a second side (200) opposite and parallel to the first side (102), characterized in that the housing (100) further comprises two sets of ribs (204, 205) extending between the first (102) and second (200) side, and wherein ends of the ribs (204, 205) on the second side (200) are radially distributed per set about the screw openings (202, 203), and wherein the ends of the ribs (204, 205) on the first side (102) converge per set to a point (206, 207) of the edge of the motor opening (104).

Description

HOUSING FOR HOUSING A GEARBOX

OF A ROTARY SCREW COMPRESSOR

Technical domain

[01] The present invention relates to a housing for housing a mechanical system, such as a gearbox, for transferring a mechanical torque from a motor to one or more shafts of a rotary screw compressor.

State of the art

[02] A rotary screw compressor is a machine designed to produce compressed gases, such as compressed air. The compressed gas at a certain operating pressure is then used in a variety of applications, such as, for example, to power other machines.

[03] A rotary screw compressor comprises a twin screw, being the male and female rotor, which rotate in opposite directions as the volume between them and the housing decreases. Each screw is provided with a screw profile and as the rotors rotate, the gas is compressed between these rotors.

[04] In order to rotate the rotors, a drive is required consisting of an electric motor, a power turbine, a diesel engine, or any other suitable drive. However, the speed at which the screws of the rotary screw compressor have to rotate to achieve a desired working pressure usually does not correspond to the speed of the drive. Notwithstanding, even if the speeds match, the mechanical torque from the drive still needs to be transferred to the screws.

[05] To transmit the mechanical torque, a mechanical system, configured to transmit this mechanical torque, is used. This mechanical system is, for example, a set of gears that mechanically connect the shafts of the rotors to the drive.

[06] For reasons of safety and stability, on the one hand, this mechanical system must be shielded, and, on the other hand, parts of the mechanical system together with the drive shaft and the rotors of the rotary screw compressor must be securely supported.

[07] Accordingly, there is a need for a housing to safely, stably and permanently house a mechanical system for transmitting a mechanical torque from a drive to a rotary screw compressor.

Summary of the invention

[08] It is an object of the present invention to provide a housing for housing a mechanical system for transmitting a mechanical torque from a drive to a rotary screw compressor.

[09] This object is achieved, according to a first aspect of the invention, by providing a housing according to claim 1.

[10] The invention comprises a substantially beam-shaped housing for housing a mechanical system configured to transmit a mechanical torque from a drive shaft of a motor to a first and/or second screw shaft of a rotary screw compressor, the housing comprising a motor opening on a first side suitable for insertion of the drive shaft, and two screw openings on a second side opposite and parallel to the first side, the two screw openings each suitable for insertion of the first and second screw shaft, respectively, characterised in that the housing further comprises a first and second set of ribs, respectively, extending between the first and second side, and wherein ends of the ribs on the second side per set are radially distributed about the first and second screw opening, respectively, and wherein the ends of the ribs on the first side per set converge towards a first or second point, respectively, on the edge of the motor opening.

[11] It should be understood that the housing is substantially beam-shaped. Ageometric beam or rectangular block is a polyhedron with six rectangular faces, eight corners, and twelve edges, also called ribs. The substantially beam-shaped shape of the housing means that one or more corners and/or edges may be wholly or partially rounded. Furthermore, one or more recesses and/or protrusions may also be present. Thus, it is possible to deviate from the exact shape of a geometric beam, wherein the skilled person clearly recognizes the shape of the outer surface of the housing as being beam-shaped.

[12] The drive shaft originates from the drive of an electric motor, a power turbine, a diesel engine, or any other engine suitable for this purpose. This drive shaft of the drive is inserted into the housing on one side thereof, the first side, and further referred to as the motor side. On the side opposite to the motor side, the second side, the two shafts of the rotors or screws of the rotary screw compressor are located. This side is further referred to as the compressor side.

[13] As a rule, the drive shaft will not be axially with one of the screw shafts. Furthermore, the screw shafts are axially parallel to each other, as is usual with a rotary screw compressor. Furthermore, for an efficient mechanical transmission, the axes of the drive shaft and the screw shafts will be perpendicular to the planes determined by the motor side and/or the compressor side. As a result, the axes do have the same direction.

[14] A motor opening is provided for the insertion of the drive shaft, while screw openings are provided for the screw shafts. The housing thus has openings on two opposite sides. Furthermore, to accommodate the mechanical system, the housing will be partially internally empty.

[15] The housing is further characterized by the innovative concept that it includes two sets of internal ribs for rigidity and strength of the housing for an efficient torque transfer. Hereinafter, it will be further clarified how these sets of ribs are configured.

[16] The ribs are generally made of the same material as the rest of the housing. Alternatively, they may also be made of a different material, provided that these ribs can be fixedly bonded to the material constituting the housing.

[17] Each set of ribs extends between the first and second side, in other words, between, on the one hand, the motor side, and, on the other hand, the compressor side.

[18] The ribs are substantially elongate in the direction between these aforementioned sides, wherein the cross-sections are substantially rectangular. The ends of the ribs are radially distributed per set over the circumference of the two screw openings. In other words, the ends of the ribs of the first set are radially distributed about the circumference of the first screw opening and the ends of the ribs of the second set are radially distributed about the circumference of the second screw opening.

[19] The ribs per set then extend to the motor side, wherein the ends per set thereof meet or converge to each one respective point adjacent to the edge of the opening.

[20] By the aforementioned configuration, several advantages over the prior art can be identified.

[21] By radially distributing the ends of the ribs about the respective screw openings, vibrations caused by the rotating screws when operational, are compensated and/or absorbed by these ribs without there being a concentration of forces at a single point. In other words, the vibrations that manifest themselves about the screws and are distributed about them, are absorbed by the ribs.

[22] When the components in the housing are operational, hence when the mechanical torque from the drive motor is transferred to the screws through the drive shaft, most of the vibrations will originate from the rotating screws. This can be explained by the operation of the compressor as compared to the operation of the driving motor. Since ambient air or other gas is compressed in the compressor, it is more dependent on external factors that may affect the operation, while the drive motor may operate more stably compared to the compressor. Note, however, that this depends on the drive technology used. An electric motor will generally run more stably compared to an internal combustion engine.

[23] On the motor side, the ends of the ribs converge to one point per set. The vibrations from the rotating screws can then be concentrated per screw in one point about the motor opening. This allows the emphasis on the motor side to make the zone on and about these points sufficiently strong, rigid and/or sturdy to absorb these vibrations.

[24] Another advantage is that this configuration keeps the ribs out of reach of rotating components located within the housing. The ribs can then be positioned such as to not interfere with the operation of the mechanical transmission system.

[25] Preferably, the ribs have no sharp transitions. This has the advantage that no additional stress concentrations will arise.

[26] According to an embodiment, the points to which the ends of the ribs of the first and second set converge, are located in a plane defined by the geometric axes of the screw shafts when mounted or placed in the screw holes.

[27] In other words, the points on the edge of the motor opening to which the ribs converge to absorb the vibrations are located in the plane perpendicular to the plane of the motor side and further defined by the geometric axes or diameters of the screw shafts when mounted in the screw holes. As a result, vibrations that arise in the axial direction of the screw shafts can be efficiently absorbed without causing again an imbalance via the ribs. This imbalance could arise if these points were not located in the aforementioned plane and a mechanical momentum would arise between these points and points located on the geometric axes of the screw shafts.

[28] According to an embodiment, the cross-section of the ribs gradually increases from the first to the second side.

[29] Thus, according to this embodiment, the cross-section of the ribs will increase from the points at or on the edge of the motor opening to the points about the circumference of the screw openings. This creates sufficient stiffness on the side where the largest vibrations will occur, as these vibrations are concentrated at these points, as already explained above.

[30] Preferably, according to an embodiment, an edge of one or more ribs in the longitudinal direction between the two ends will further engage on at least one side different from the motor side and/or the compressor side, preferably on both two other sides. [31] The ribs engage on the insides of the housing where the motor is located and on the side where the compressor is located, or at least the drive shaft or the screw shafts, respectively. Due to the predominantly rectangular shape of the housing, at least four other sides can be distinguished on the inside. The ribs will then preferably also engage on one or two other insides. Engaging means that these ribs are fixedly connected thereto with an edge by, for example, a casting process or a welding technique, and they are integral. As a result, the vibrations are even better distributed over the housing.

[32] Furthermore, according to an embodiment, the housing may further comprise a third set of straight ribs extending between, on the one hand, the side of the motor opening, or the motor side, and the side of the screw openings, or the compressor side, and, on the other hand, according to the direction of a side plane perpendicular to the plane of the motor side or the compressor side. These ribs then further provide sufficient stiffness in the direction perpendicular to the plane defined by the geometric axes of the screw shafts.

[33] Additionally, the housing may further comprise a fourth set of ribs extending between the motor side and the compressor side and perpendicular to the ribs of the third set. This then even provides further additional stiffness in this direction, thereby guaranteeing, in combination with the other third set of ribs, sufficient stiffness in each orthogonal direction of the housing. This allows the mechanical torque to be efficiently transferred from the motor to the screws of the compressor.

[34] Finally, the ends of the ribs of the third and/or fourth set can engage on the edge of the motor opening. As a result, the ribs extend over the entire permissible length to obtain maximum rigidity of the housing.

[35] According to an embodiment, the second side, hence the compressor side, further comprises a second motor opening for supporting the drive shaft. In other words, the drive shaft extends along two outer sides of the housing, with the drive shaft being supported on the compressor side. As a result, a bending of the drive shaft in the axial direction is accommodated and thus prevented, or at least reduced. [36] Furthermore, preferably according to an embodiment, the motor opening on the first side is suitable for insertion of a shroud or housing of the motor. In other words, the motor opening on the motor side is sufficiently large to encompass the housing of the motor. This allows the motor to be secured against the housing.

[37] According to an embodiment, the screw openings are furthermore suitable for inserting a shroud or housing of the rotary screw compressor. This also allows the compressor to be permanently attached to the housing for housing the mechanical system. Together with the motor opening that houses the motor shroud, one resistant system can then be mounted, allowing the transmission of the mechanical torque to take place efficiently.

[38] According to a second aspect of the invention, a substantially beam-shaped housing for housing a mechanical system according to the first aspect of the invention is disclosed, the housing obtained via permanent moulding technique and/or a lost moulding technique.

[39] The housing then consists of a single piece, consisting of cast steel or cast iron, moulded in the desired shape as already described above.

[40] According to a third aspect, a compressor unit is disclosed, comprising a motor and a rotary screw compressor, and further comprising a housing according to the first aspect of the invention for transmitting a mechanical torque from a drive shaft of the motor to a first and/or second screw shaft of the rotary screw compressor.

Brief description of the drawings

The invention will be further illustrated with reference to the figures, wherein:

[41] Fig. 1 illustrates a front view of the motor side according to an embodiment of the invention;

[42] Fig. 2 illustrates a front view of the compressor side according to an embodiment of the invention;

[43] Fig. 3 illustrates a side view of the housing according to an embodiment of the invention;

[44] Fig. 4 illustrates a view of the inside at the motor side of the housing according to an embodiment of the invention;

[45] Fig. 5 illustrates a view at the inside at the compressor side of the housing according to an embodiment of the invention;

[46] Fig. 6 illustrates a three-dimensional side view of the compressor side according to an embodiment of the invention; and

[47] Fig. 7 illustrates a three-dimensional side view of the motor side according to an embodiment of the invention.

Description of embodiments

[48] The present invention will be described with reference to certain embodiments and with reference to certain drawings, but the invention is not limited thereto and is defined only by the claims. The drawings described are only schematic and non-limiting. In the drawings, the size of certain elements may be exaggerated and not drawn to scale for illustrative purposes. The dimensions and relative dimensions do not necessarily correspond to actual practical embodiments of the invention.

[49] In addition, the terms first, second, third and the like are used in the specification and in the claims to distinguish between like elements and not necessarily to describe a sequential or chronological order. The terms are interchangeable under appropriate circumstances and the embodiments of the invention may be used in sequences other than those described or illustrated herein.

[50] In addition, the terms at top side, bottom side, over, under and the like in the specification and claims are used for illustrative purposes and not necessarily to describe relative positions. The terms so used are interchangeable under appropriate circumstances and the embodiments of the invention described herein may be used in orientations other than those described or illustrated herein.

[51] Furthermore, the various embodiments, although referred to as "preferred embodiments", are to be construed as exemplary in which the invention may be practiced rather than as a limitation on the scope of the invention.

[52] The term "comprising" used in the claims should not be construed as being limited to the means or steps set forth below; the term does not exclude other elements or steps. The term should be interpreted as specifying the presence of the named features, elements, steps or components referred to, but does not exclude the presence or addition of one or more other features, elements, steps or components, or groups thereof. The scope of the expression "a device comprising means A and B" should therefore not be limited to devices consisting only of the components A and B. The meaning is that, with respect to the present invention, only the components A and B of the device are listed, and the claim is further to be interpreted as including equivalents of these components.

[53] The housings shown in the figures are housings for housing a mechanical system for transmitting a mechanical torque from a drive shaft of a motor to a rotary screw compressor.

[54] Fig. 1 is a view of the motor side 102 of the housing 100 according to an embodiment of the invention. The housing 100 is predominantly beam-shaped, wherein one or more corners may be rounded, such as, for example, corner 101. On the motor side 102 of the housing 100 there is a circular 103 motor opening 104 suitable for housing a drive shaft together with a shroud of the motor.

[55] Through the motor opening 104, there is a view of the inside of the housing which is discussed in the following figures.

[56] Fig. 2 illustrates the same housing 100, but from the view of the compressor side 200. On this side 200, an opening 201 is also provided for supporting the drive shaft of the motor. This opening 201 is also visible in Fig. 1 through the motor opening 104. Both openings 104, 201 are formed by circles 103, wherein the centre of the motor opening 104 axially coincides with the centre of the opening for the drive shaft 201. In other words, when the circles forming the openings 104, 201 are projected onto each other, their respective centres coincide.

[57] On the compressor side 200 as illustrated in Fig. 2, it is further shown that two openings 202, 203 are provided to connect and accommodate the screws of a rotary screw compressor. The shape of these openings 202, 203 is not circular, but adapted to the particular shape of a rotary screw compressor, and in particular to its screws.

[58] Through these openings 202, 203, the ribs 205 and 204, respectively, are visible which converge per set 205, 204 to respective points 207 and 206, starting from the compressor side 200 to the motor side 102. The points 206 and 207 are thus located on the edge 103 of the motor opening 104. In other words, the ribs 204, 205 extend between the motor side 102 and the compressor side 200, wherein on the compressor side 200 the ends are distributed over the edge of the respective openings 202 and 203 and converge towards point 207 and point 206, respectively.

[59] This set of ribs 205, 204 are further illustrated in Fig. 4 illustrating a view of the inside on the motor side 102 of the housing 100. This view corresponds to section IV- IV of Fig. 3, which illustrates a side view of the housing 100.

[60] On Fig. 3, it is further seen that, at the opening 201 for the drive shaft, a protrusion 301 is provided to support the drive shaft.

[61] Fig. 5 also illustrates the inside, but from an opposite view, namely with a view to the compressor side 200, hence according to section V-V as shown in Fig. 3.

[62] In Fig. 4 it can be seen that the ribs 204, 205 on this side engage on points 206, 207 on the edge of the motor opening 104. In other words, the ribs 204, 205 each per set engage on a common point 206, 207 on the edge of the motor opening 104. [63] On the other hand, as illustrated in Fig. 5, the ends are distributed over the edge of the screw holes 202 and 203. For the set of ribs illustrated by reference 204 they engage on points 503-505, and for the set of ribs illustrated by reference 205 they engage on points 500 -502.

[64] Furthermore, the housing 100 may internally comprise a set of straight ribs extending, on the one hand, between the motor side 102 and the compressor side 200 and, on the other hand, according to a direction of a side face of the housing 100. This is illustrated by ribs 400-404 in both Fig. 4 and Fig. 5. In addition, perpendicular to these straight ribs 400-404, a fourth set of ribs can be provided, illustrated by ribs 510-511 in Fig. 4 and Fig. 5.

[65] According to an embodiment, this perpendicular direction of the straight ribs can be locally deviated from, as illustrated by rib 404. Furthermore, additional ribs can be provided to reinforce the housing, but it should further be understood that these are optional, whereby it is the set of ribs 204 and 205 which provides an efficient mechanical torque transfer from the drive shaft of the motor to the first and/or second screw shafts of the rotary screw compressor according to the innovative aspect of the invention.

[66] Finally, Fig. 6 and Fig. 7 illustrate a three-dimensional side view of the housing 100, as viewed in the direction of the compressor side 200 and motor side 102, respectively. On the compressor side 200, point 207 can be seen through the screw opening to where the set of ribs 205 converge. Furthermore, the ribs 204 extending between the compressor side 200 and the motor side 102 are visible. Also, the opening 201 is once again illustrated for supporting the drive shaft of the motor. In Fig. 7, this opening 201 is also illustrated, this time from the view of the motor side 102.

Claims

1. A beam-shaped housing (100) configured for housing a mechanical system configured to transmit a mechanical torque from a drive shaft of a motor to a first and/or second screw shaft of a rotary screw compressor, the housing (100) comprising a motor opening (104) on a first side (102) adapted for insertion of the drive shaft, and two screw openings (202, 203) on a second side (200) opposite and parallel to the first side (102), the two screw openings (202, 203) each suitable for inserting the first and second screw shafts, respectively,

CHARACTERISED IN THAT the housing (100) further comprises a first (204) and second set (205) of ribs, respectively, extending between the first (102) and second (200) side, and wherein ends of the ribs on the second side (200) per set (204, 205) are radially distributed about the first (500-502) and second (503-505) screw opening, respectively, and wherein the ends of the ribs on the first side converge per set to a first (206) and second (207) point, respectively, on the edge of the motor opening (104).

2. The housing (100) according to claim 1, wherein the points (206, 207) to which the ends of the ribs of the first (204) and second (205) set, respectively, converge are located in a plane defined by the geometric axes of the screw shafts, when attached.

3. The housing (100) according to any one of the preceding claims, wherein the crosssections of the ribs (204, 205) gradually increase from the first side (102) to the second side (200).

4. The housing (100) according to any one of the preceding claims, wherein an edge of a rib along the longitudinal direction between the two ends engages on at least one side different from the first (102) or second (200) side.

5. The housing (100) according to any one of the preceding claims, further comprising a third set of straight ribs (400-404) extending between, on the one hand, the first (102) and second (200) side and, on the other hand, according to a direction of a side face of the substantially beam-shaped housing (100) perpendicular to a plane defined by the first (102) or second (200) side.

6. The housing (100) according to claim 5, further comprising a fourth set of straight ribs (510-511) extending, on the one hand, between the first (101) and second (200) side and, on the other hand, according to a direction perpendicular to the direction according to the third set (400-404).

7. The housing (100) according to claim 6, wherein ends of one or more ribs of the third (400-404) and/or fourth (510-511) set engage on a point of the edge of the motor opening (104).

8. The housing (100) according to any one of the preceding claims, further comprising a second motor opening (201) on the second side (200) adapted for supporting the drive shaft.

9. The housing (100) according to any one of the preceding claims, wherein the motor opening (104) on the first side (102) is further suitable for insertion of a shroud of the motor.

10. The housing (100) according to any one of the preceding claims, wherein the screw openings (202, 203) are further suitable for insertion of a shroud of the rotary screw compressor.

11. A substantially beam-shaped housing (100) for housing a mechanical system according to any one of the preceding claims, obtained via a permanent moulding technique and/or a lost moulding technique.

12. A compressor unit comprising a motor and a rotary screw compressor and further comprising a housing (100) according to anyone of the preceding claims, configured to transfer a mechanical torque from a drive shaft of the motor to a first and/or second screw shaft of the rotary screw compressor.