TW202202724A - Dry vacuum pump and method for manufacturing same - Google Patents

Abstract

Dry vacuum pump (1) comprising: - a stator (2) comprising at least one first and at least one second complementary half-shells (7, 8), each half-shell (7, 8) comprising at least one half-partition (13e) joined together with a half-partition (14a-14e) of the other half-shell (8) to form a separating partition between two successive pumping chambers of pumping stages (3a-3f) mounted in series between a suction (4) and a discharge (5) of the vacuum pump (1), - two rotor shafts configured to turn synchronously in reverse directions in the pumping chambers, characterized in that at least one half-partition (13e, 14d, 14e) of a half-shell (7, 8) is fitted by assembly in a cradle (15) of the half-shell (7, 8).

Description

Dry vacuum pump and method of making the same

The present invention relates to dry vacuum pumps such as Roots type or Claw type, in particular, multistage dry vacuum pumps. The present invention also relates to a method for manufacturing such a vacuum pump.

Multistage dry vacuum pumps contain several pumping stages in series, where the gas to be pumped is circulated between suction and discharge. Known vacuum pumps that can be distinguished include those with rotating vanes, also known as "Roots" vacuum pumps, or those with beaks, also known as "Claw" vacuum pumps. These vacuum pumps are called "dry" because in operation, the rotors rotate inside the stator without mechanical contact between the rotors or with the stator, so that no oil is used in the pumping stage. In some pumping applications, such as those used in the semiconductor, flat panel display, photovoltaic, and coating industries, the gases used can be corrosive, and the residues from the process can include abrasive powders, which can Damage all or some of the static components, especially the high-pressure pumping stages, which also have minimal axial running clearance. A multi-stage vacuum pump with a sliced structure, that is, the stator is formed by axially assembling stator elements, can better solve this problem. In fact, their disassembly on the one hand makes them easy to clean, and on the other hand, their discreteness makes it possible to replace damaged components without having to replace all the stators. Correspondingly, the assembly of a rather complicated vacuum pump requires more positioning and fixing components and sealing components between each interface. This results in an increase in the production cost of the components and the accompanying labor cost. For example, a multi-stage vacuum pump with a half-shell architecture as described in US 6,572,351 B2 document makes it possible to reduce these costs. On their own, these pumps can be disadvantageous during maintenance, since the half-shells or all of the half-shells have to be replaced even though only a part of the half-shells may potentially be damaged. Furthermore, the cost of obtaining the half-shells is relatively high because of the machining precision required to fabricate the pumping chamber and its separating baffles. Another problem associated with half-shell architectures is inherent to machining limitations. In fact, machining requires the use of special milling cutters, which require relatively long machining times due to the large amount of material to be milled. The diameter of the shaft passage determines the diameter of the shank of the milling cutter set, and the ratio between the shaft passage and the diameter of the pumping chamber allows or prevents the use of the combination tool. The flexural stiffness of the milling cutter set relative to these constraints determines the geometrical qualities of the chamber and spacer, and the width of the thinnest pumping chamber determines the width of the milling cutter that cuts it. In fact, a compromise is sought between these technical fabrication constraints and design constraints, with the result that thin pumping chambers are sometimes impossible to fabricate.

An object of the present invention is to at least partially address at least one of the above disadvantages. To this end, the subject matter of the present invention is a dry vacuum pump, comprising: - a stator comprising at least one first and at least one second complementary half-shell, each half-shell comprising at least one spacer half, the at least one spacer half being engaged with the spacer half of the other half-shell while in series A partition is formed between two consecutive pumping chambers of the pumping stage installed between the suction and discharge ports of the vacuum pump, - two rotor shafts configured to rotate synchronously in opposite directions in the pumping chambers, It is characterised in that the at least one half-spacer of the half-shell is assembled in the bracket of the half-shell by assembly. Thus, the half-shell system is easier to manufacture, especially compared to brackets that can be machined from the front without contour milling, which reduces manufacturing costs. Furthermore, with this architecture, pumping chambers with narrow axial dimensions can be fabricated without being limited by the size of the fabrication tool. The vacuum pump may also include one or more of the features described below. The at least one half-spacer can be assembled in the carrier by detachable assembly. Thereby, parts of the half-shells can be easily removed for cleaning or replacement in case of blockage or damage. Therefore, maintenance costs can be reduced. The at least one spacer half can be fixed to the bottom of the half-chamber removably fitted in the bracket of the half-shell, the bottom of the half-chamber and the at least one spacer half being made in a removable insert of the half-shell in the file. Since the insert is removable, it can be separated from the carrier to clean the bottom of the half-chamber. At least one half-shell may include: - at least one removable fixing member, such as a screw, for fixing the removable half-spacer to the bracket, and/or - at least one positioning member, such as a pin or key, for positioning the removable spacer half in the carrier. The half-shell may comprise at least one insert carrying the at least one spacer half with a semi-fixing flange, the at least one fixing member and/or the at least one positioning member being for example axially inserted into the half into the fixing flange and into the bracket and/or into another fixing flange. The at least one fixing member and/or the at least one positioning member can be radially inserted into the bracket through the removable half-spacer. The vacuum pump may include at least one interstage channel configured to connect the outlet of the previous pumping stage to the inlet of the next pumping stage, and at least a portion of the interstage half channel is fabricated in the The insert part of the half shell is opened at the side of the insert part, the insert part carries the half spacer and is assembled in the bracket by a detachable assembly method. Access to and from the interior of the interstage channel is then facilitated, which simplifies its cleaning and fabrication. Another advantage of making interstage channels in removable inserts is that it allows very thin channels to be made. The at least one interstage half-channel can be formed in the side of the spacer half, in the half-fixing flange, also allowing the insert to be fixed to the bracket. The vacuum pump may comprise two interstage half-channels partially formed in the sides of the at least one insert, the interstage channels being located on both sides of the half-spacer. At least one half-spacer can be assembled in the carrier by means of a press fit. The vacuum pump may include at least one interstage channel configured to connect the outlet of the previous pumping stage to the inlet of the next pumping stage, and at least a portion of the interstage half channel is fabricated in the into the insert of the half-shell, and opening on the side of the insert, the insert carries the half-spacer and is assembled into the bracket by means of press-fit assembly. The at least one spacer half or an insert carrying the at least one spacer half assembled by assembly is more resistant to corrosion and/or wear than the body material or coating of the half-shell such as cast iron, such as Made of materials or coatings that contain nickel. More durable materials or coatings are also usually the most expensive, so limiting them to the parts assembled by assembly may limit their use to the parts of the half-shell that are most susceptible to external erosion. The at least one spacer half and the at least one spacer half assembled by assembly can also be assembled by assembly. At least one half-shell may include at least two spacer halves assembled by assembly, the at least two spacer halves being joined with two spacer halves assembled by assembly of the other half-shell to separate the three consecutive pumping chambers. The half-parts of the half-shells separating the last pumping stage from the pumping chambers of the penultimate pumping stage can be assembled by assembly. The spacers of the half-shells separating the second-to-last pumping stage from the pumping chambers of the third-to-last pumping stage can be assembled by assembly. Preferably, the pumping stages are located on the discharge side of the vacuum pump, that is, the pumping stages are located on the highest pressure side where the risk of corrosion and abrasion erosion is greatest and where it is the narrowest, by assembling the pumping stages. to fit in the bracket. The at least one half-shell may comprise at least one partition half assembled by removable assembly and at least one non-removable partition half. The at least one non-removable half-spacer is, for example, produced in the mass of the half-shell or assembled in the carrier by means of press-fit fitting. For example, the non-removable spacer halves are the spacer halves between the first pumping stages where pressure is lowest and the risk of corrosion or wear is lowest. These non-removable half-spacers make it possible to maintain the advantages of saving time during assembly and in terms of fixing and positioning members of the half-shell structure. The half-spacer joined with the non-removable half-spacer may also be non-removable. Another subject matter of the present invention is a method of manufacturing a dry vacuum pump, wherein at least one spacer half of a half-shell is assembled by detachable assembly in a bracket of the half-shell, or is press-fitted into the half-shell in this bracket of the shell.

The drawings have been simplified for clarity. Only elements necessary to understand the invention are shown. The following examples are examples. Although the description refers to one or more embodiments, this does not necessarily mean that each reference is to the same embodiment or that the features apply only to a single embodiment. Simple features of different embodiments may also be combined or interchanged to provide other embodiments. A roughing vacuum pump is defined as a positive displacement vacuum pump that is configured to use two rotor shafts to suck in, transfer, and then discharge the gas to be pumped at atmospheric pressure. The rotor shaft is driven to rotate by the motor of the rough vacuum pump. "Upstream" is understood to mean an element placed before another element with respect to the direction of circulation of the gas to be pumped. Conversely, "downstream" is understood to mean an element placed after another element with respect to the direction of circulation of the gas to be pumped. The axial system is defined as the longitudinal direction of the pump in which the axis of the rotor shaft extends. The dry vacuum pump 1 of Figure 1 comprises a stator 2 forming a pumping chamber of at least two pumping stages 3a-3f, such as between two and ten pumping stages (six in the illustrative example) , installed in series between the suction port 4 and the discharge port 5. The dry vacuum pump 1 is, for example, a rough vacuum pump. The vacuum pump 1 further comprises two rotor shafts 6 (Fig. 2), which are configured to rotate synchronously in opposite directions in the pumping chambers of the pumping stages 3a-3f, so that the rotors are in the suction port 4 and the discharge port 5 Between drives the gas to be pumped. The rotor shaft 6 can be in one piece, or can be made by assembling various additional elements. The rotor has, for example, blades of the same profile, for example, of the "Roots" type with two blades (Fig. 2) or more, or of the "claw" type, or another similar principle of a positive displacement vacuum pump of. The shaft train carrying the rotor is driven by a motor (not shown) located, for example, at the end of the vacuum pump 1 , for example on the discharge port 5 side. Each pumping stage 3a-3f of the stator 2 is formed by a pumping chamber receiving two conjugate rotors, the pumping chambers comprising respective inlets and outlets. During rotation, the gas drawn in from the inlet is trapped in the volume created by the rotor and stator 2, and is then driven by the rotor to the next stage. Successive pumping stages 3a-3f are connected in series one after the other by respective interstage channels 9a-9e, 10a-10e which connect the preceding pumping stage 3a- The outlet of 3e is connected to the inlet of the next pumping stage 3b-3f. The vacuum pump 1 comprises, for example, two conveying channels 9a-9e, 10a-10e, which are formed in groups on either side of the pumping chamber for pumping the previous pumping stage The outlet of the pumping chamber is connected in parallel to the inlet of the next pumping stage (Fig. 3). The inlet of the first pumping stage 3a is connected to the suction port 4 of the vacuum pump 1 . The outlet 20 of the last pumping stage 3f is connected to the discharge port 5 . The axial dimensions of the rotor and pumping chamber are eg equal or decreasing with the pumping stage 3a, located on the side of the suction port 4, receiving the rotor 6 of the largest axial dimension. These vacuum pumps are called "dry" because in operation the rotors rotate inside the stator 2 without mechanical contact between the rotors or with the stator 2, so that no oil is used in the pumping stages 3a-3f. The stator 2 comprises at least one first and at least one second complementary half-shell 7 , 8 . The half-shells are closed, for example, at their axial ends by first and second end pieces (not shown). The half-shells 7, 8 are joined to each other by the joining surfaces 11 to form the pumping chambers of at least two pumping stages 3a-3f. The engagement surface 11 is, for example, a flat engagement surface, such as a mid-plane through the dry vacuum pump 1 . This flat engagement surface 11 contains, for example, the axis of the rotor shaft 6 . This flat engagement surface 11 may be strictly flat, or may for example have a complementary relief form or grooves 12 for the side rails of the seal between the half-shells. This can be better seen in Figure 3, which shows the half-shells disassembled, the successive pumping chambers being separated from each other by dividing partitions which are connected to the rotor shaft by the The longitudinal direction defined by the axial direction of 6 is at right angles. Of course, apertures are formed in the dividing spacers and in the end pieces for the passage of the rotor shaft 6 . The pumping chambers, dividing partitions 13a-13e, 14a-14e, and interstage channels 9a-9e, 10a-10e are formed partly in the first half-shell 7 and partly in the second half-shell 8. Thus, each half-shell 7 comprises at least one half-spacer 13a-13e which is joined with the half-spacer 14a-14e of the other half-shell 8, while in two consecutive pumping chambers A separation spacer is formed therebetween. Furthermore, each half-shell 7 may comprise at least one half-channel 9a-9e, 10a-10e, which half-channel 9a-9e, 10a-10e joins with the half-channel of the other half-shell 8 to form an interstage channel 9a -9e, 10a-10e. At least one half-spacer 13d, 13e, 14d, 14e of the half-shell 8 which joins together with the half-spacer 13d, 13e, 14d, 14e of the other half-shell 7 for separating the two successive pumping chambers is tied by Fitted in the bracket 15 of the half-shell 8 by assembly. At least one half-spacer 13d, 13e, 14d, 14e is fitted in the bracket 15 by detachable assembly, or is press-fitted into the bracket 15, as will be described later with reference to Figures 11 to 13 Show. A "removable" element is understood to be an additional element, as opposed to a "non-removable" element, which can be removed or replaced and fixed without particular difficulty, which "non-removable" element means Refers to additional elements that cannot simply be removed without damage. Assembly by press fit is considered a "non-removable" assembly. With at least one half-spacer 13d, 13e, 14d, 14e assembled by detachable assembly in the bracket 15, or press-fitted into the bracket 15, the half-shells 7, 8 are easy to manufacture, This reduces manufacturing costs, especially in relation to brackets 15 that can be machined from the front without contour milling. Furthermore, with this architecture, pumping chambers with narrow axial dimensions can be fabricated without being limited by the size of the fabrication tool. With at least one half-spacer 13d, 13e, 14d, 14e fitted in the bracket 15 of the half-shells 7, 8 by detachable assembly, parts of these half-shells 7, 8 can be easily removed for Clean or replace if clogged or damaged. Therefore, maintenance costs can be reduced. Furthermore, according to the first exemplary embodiment shown in Figures 1 to 8, at least one half-spacer 13d, 13e, 14d, 14e can be fixed to the bracket 15 detachably fitted in the half-shells 7, 8 the bottom of the half-chamber. The bottom of the half-chamber is a hollow volume bounded by the at least one removable half-partition 13d, 13e, 14d, 14e and by the lateral half-walls 22. This hollow volume is closed axially by another removable half-spacer or by an end piece or by a non-removable half-spacer. This half-chamber bottom is tied together at the joint surface 11 with the half-chamber bottoms of the other half-shells 7, 8 to form the pumping chamber. The half-chamber bottom, that is to say, the lateral half-walls 22 and the at least one half-partition 13d, 13e, 14d, 14e are made in assembly by removably fitting in the brackets 15 of the half-shells 7, 8 in the insert 23 (Fig. 4). Because the insert 23 is removable, it can be separated from the bracket 15 to clean the bottom of the half-chamber. Furthermore, since the interior of the interstage channel is also difficult to access, which complicates its cleaning and fabrication, all or part of it can be fabricated in the removable insert 23, especially the one on the side of the discharge port 5. and others. Thus, according to an exemplary embodiment, at least a part of the interstage half-channels 9e, 10e is made in the inserts 23 of the half-shells 7,8. This part of the interstage half-channel is tied open on the side of the insert 23 (Fig. 7). This part of the interstage half-channels 9e, 10e is then an open groove, which is closed axially by a removable half-spacer or by an end piece or by a non-removable half-spacer, thus forming an interstage half channel. The interstage half-channels are joined at the joint surface 11 with the interstage half-channels 9e, 10e, 9d, 10d of the other half-shells 7, 8 to form the interstage channels 9e, 10e, 9d, 10d. More specifically, a part of the interstage half-channels 9e, 10e, 9d, 10d may be formed together with the half-spacers 13d, 13e, 14d, 14e, for example in the semi-fixed flange 16 which also allows insertion Piece 23 is fixed to bracket 15 . For example, the interstage half-channels 9e, 10e, 9d, 10d are closed in the pumping direction of the gas by the semi-fixed flange 16 of the preceding pumping chamber. Two interstage half-channels 9e, 10e, 9d, 10d are, for example, partially formed in the sides of at least one insert 23, the interstage channels 9e, 10e, 9d, 10d being located in the half-spacer 13d, 13e, 14d, both sides of 14e. The four interstage half-channels, for example, form a ring around the pumping chamber. Another advantage of making interstage channels in removable inserts 23 is that very thin channels can be made. Removable inserts 23 comprising the half-spacers 13d, 13e, 14d, 14e and, if appropriate, the half-chamber bottoms and/or the interstage half-channels, can be made in a material other than the body material of the half-shells 7, 8 such as cast iron or The coating is made of materials or coatings that are more resistant to corrosion and/or wear and/or high temperatures, such as nickel-containing eg nickel or NiP (nickel-phosphorus). Because more durable materials or coatings are also generally the most expensive, limiting them to inserts 23 may limit their use to the parts of the half-shell that are most susceptible to external erosion. According to an exemplary embodiment, which can be better seen in Figure 4, at least one half-shell 7, 8 comprises at least one removable fixing member 24, such as a screw, or a series of screws, here eight, for securing the removable half-spacer 13d, 13e, 14d, 14e to the bracket 15, and/or at least one positioning member 25, such as a pin, for positioning the removable half-spacer in the bracket rack 15. At least one insert 23 can have a semi-fixed flange 16, in particular in its interior can form part of an interstage semi-channel. The at least one fixing member 24 and/or the at least one positioning member 25 are, for example, axially inserted into the semi-fixed flange 16 and into the bracket 15 and/or into the other fixed flange 16 . More specifically, the removable insert 23 and the bracket 15 may have respective semi-fixed flanges 16 . The semi-fixed flange 16 has a flat and complementary form in which holes 17 can be formed for fixing members 24 and/or positioning members 25 . For example, through holes 17 are formed in the semi-fixed flanges 16 of the removable half-spacers 13d, 13e, 14d, 14e. The at least one fixing member 24 is inserted into at least two consecutive semi-fixed flanges 16, namely the flange of the removable half-spacer 13e, 14e and the flange of the other removable half-spacer 13d, 14d or flanges of the bracket 15 for securing the removable half-spacers 13d, 13e, 14d, 14e to the bracket 15. Thus, the semi-fixed flange 16 of the removable half-spacer 13d, 13e, 14d, 14e can be clamped between the end piece and the other removable half-spacer 13d, 14d, or between the removable half-spacer 13d, 14d Between the spacers 13e, 14e and the semi-fixed flange 16 of the bracket 15. According to another exemplary embodiment not shown, the at least one removable fixing member 24 is a semi-elastic washer or metal clip, which is inserted axially between the end piece and the other removable half spacer 13d , 14d, 13e, 14e or inserted between the removable half-spacers 13d, 14d, 13e, 14e and the bracket 15 to clamp at least one removable half-spacer 13d, 14d, 13e, 14e to bracket 15. The spacer halves 13d, 13e, 14d, 14e of the other half-shell 7, 8 joined together with the at least one removable spacer half 13d, 13e, 14d, 14e can also be removably assembled. For example, there are two facing inserts 23 . For example, provision is made in that at least one half-shell 7, 8 comprises at least two removable half-spacers 13d, 13e joined with two removable half-spacers 14d, 14e of the other half-shell 8 to separate Three consecutive pumping chambers 3d, 3e, 3f. For example, the partitions 13e, 14e of the half-shells 7, 8 separating the last pumping stage 3f from the pumping chambers of the penultimate pumping stage 3e are removable (4th picture). The half-partitions 13d, 14d of the half-shells 7, 8 separating the second-to-last pumping stage 3e and the pumping chambers of the third-to-last pumping stage 3d are provided to be removable of. More specifically, the provision of removable inserts 23, which may also consist of facing halves 13e, 14e and, if appropriate, half-chamber bottoms and/or interstage half-channels, may be of more durable material or Coating as the last pumping stage and the penultimate pumping stage insert. Preferably, the pumping stages 3f, 3e located on the side of the discharge port 5 of the vacuum pump 1, that is to say on the highest pressure side, where the risk of corrosion and abrasion erosion is greatest, are at least partially detachable. . Thus, the spacer halves of the insert 23 can be easily replaced or cleaned. Furthermore, it is these last pumping stages that are the narrowest and therefore the most difficult to machine of the half-shells of the prior art. For example, the last two pumping stages 3e, 3f have identical inserts 23, which further simplifies manufacture. The other half-spacers 13a-13c, 14a-14c may be non-removable (Figs. 5 and 6). For example, it is provided that at least one half-shell 7, 8 comprises at least one half-spacer 13d, 13e, 14d, 14e assembled by removable assembly, and at least one non-removable half-spacer 13a-13c, 14a-14c . The spacer halves 13a-13c, 14a-14c joined together with the spacer halves 13a-13c, 14a-14c assembled by non-removable assembly are also assembled by non-removable assembly. At least one non-removable half-spacer 13a-13c, 14a-14c is for example made in the mass of the half-shells 7, 8 or assembled in the bracket 15 of the half-shells 7, 8 by means of a press fit. For example, the non-removable half-spacers 13a-13c, 14a-14c are those between the first pumping stages 3a-3c, where the pressure is lowest and the risk of corrosion or wear is highest not tall. These non-removable half-spacers 13a-13c, 14a-14c make it possible to maintain the advantages of saving time in assembly and in terms of fixing and positioning members of the half-shell structure. After assembling the at least one removable half-partition or at least one insert 23, the half-shells 7, 8 are fastened together, for example, by means of screws. The vacuum pump 1 may also comprise at least one elastic seal, which seals are interposed between the two half-shells 7 , 8 . Alternatively, the half-shells contain a hardenable seal between the two half-shells 7 , 8 . Furthermore, and although not shown in the figures, the vacuum pump 1 may also be included upstream or downstream of the at least one pumping stage 3a-3f formed in the at least first and second half-shells 7,8 At least one single-piece pumping stage installed in series. Furthermore, the stator 2 may comprise at least two pairs of complementary half-shells. For example, the two half-shells 7, 8 form two pumping stages 3a, 3b, the other two half-shells 7, 8 form the other two pumping stages 3c, 3d, and the other two half-shells 7,8 Two further pumping stages 3e, 3f are formed, these pumping stages 3a-3f being installed in series between the suction port 4 and the discharge port 5 of the vacuum pump 1 . Figures 9A, 9B, 10A, and 10B show another exemplary embodiment for which only the half-spacers 13d, 13e of the half-shells 7, 8 are removably fitted in the brackets of the half-shells 7, 8 rack 15. In other words, in this example, the half-chamber bottoms and the interstage half-channels are not removable. Several configurations are available for the implementation of the securing member 24 and the positioning member 25 . In the example of Figures 9A and 9B, at least one fixing member 24 and/or at least one positioning member 25 are radially inserted into the bracket 15 through the removable half-spacers 13d, 13e. For example, each removable half-spacer 13d, 13e has at least two positioning members 25, such as two pins, implemented radially rather than parallel (Fig. 9A). In this case, the addition of fixation members 24, eg also radially implanted, may or may not be provided. Figure 9B shows another exemplary embodiment for which each removable spacer half 13d, 13e has at least two positioning members 25, such as keys and pins, which are radially rather than parallel implement. In this case, the addition of fixation members 24 implanted, eg also radially, parallel to the pins, may or may not be provided. The pin and the fixing member 24 are, for example, inserted into the bottom of the chamber. The key system is arranged at the edge of the half-chamber. Figures 10A and 10B show another example with at least two positioning members 25, such as two pins, and at least two fixing members 24, such as three screws, implemented axially. The pins and the screws of the fixing member 24 are inserted in parallel directions. Various implementation options make it possible to manufacture tools suitable for the manufacture of half-spacers and half-shells. Figures 11, 12, and 13 show a third exemplary embodiment. In this example, at least one spacer half 14 of the spacer half 7, 8 that joins together with the spacer half of the other half shell 7, 8 to separate two successive pumping chambers is press-fitted in the bracket rack 15. For this purpose, for example, lateral positioning grooves 26 are formed in the bracket 15 . The thickness of at least one half-spacer 14 is slightly greater than the width of the transverse positioning groove 26 of the half-shell 8 in which it is accommodated. This press fitting can be carried out under a press, or by heating the half-shells 7 , 8 and/or by cooling the at least one spacer half 14 in order to receive it in the transverse positioning groove 26 . This press-fit arrangement makes it possible to effectively fasten the at least one spacer half 14 to the bracket 15 , that is to say in particular by preventing vibrations of the at least one spacer half 14 when the vacuum pump 1 is in operation. Once this press-fit has been completed, joining can be performed on each half-shell 7 , 8 , at the top of the body of the half-shell 7 , 8 , and at the top of the at least one spacer half 14 , in particular by grinding The rework of the surface 11 ensures the complementarity of the engagement of the half-shells 7,8. Therefore, the half-shells 7, 8 are easier to manufacture, which reduces manufacturing costs. Furthermore, with this architecture, pumping chambers with narrow axial dimensions can be fabricated without being limited by the size of the fabrication tool. As in the first exemplary embodiment, the spacer halves of the other half-shell 7, 8, which are joined together with the at least one press-fit spacer half 14, can also be press-fit. For example, a press-fit fit may be provided for all the half-spacers 14 of the half-shells 7 , 8 . In this case, the bodies of the half-shells 7, 8 can be obtained by extrusion and then by machining the transverse positioning grooves 26. Alternatively, at least one half-spacer 14 of the half-shells 7 , 8 can be provided in a removable or manufactured manner with the quality of the half-shells 7 , 8 . The bodies of the half-shells 7, 8 can be obtained, for example, by casting and then machining the transverse positioning grooves 26 and the engagement surfaces 11. For example, the spacers 14 of the half-shells 7, 8 separating the pumping chambers of the last pumping stage 3f from the pumping chambers of the penultimate pumping stage 3e are press-fitted. It is these last pumping stages that are the narrowest and therefore the most difficult to machine. Furthermore, the interstage passages may be difficult to manufacture, so it is possible to provide all or part of the interstage passages to be made in the press-fit, especially thinnest, half-spacer on the side of the discharge port 5 . Thus, for example, at least a part of the interstage half-channel is made in the insert 23 of the half-shells 7, 8 and is open on the side of this insert 23, which carries the half-spacer 14 and is fitted by press-fitting way to be assembled in the bracket 15 . The at least one press-fit half-spacer 14 may also be made of a material or coating that is more resistant to corrosion and/or wear and/or high temperature than the body material or coating of the half-shells 7, 8, such as cast iron, such as nickel-containing Made of materials or coatings such as nickel or NiP (nickel-phosphorus).

1: Dry vacuum pump 2: Stator 3a-3f: Pumping stage 4: Suction port 5: Discharge port 6: Rotor shaft 7,8: half shell 9a-9e, 10a-10e: Interstage channel 11: Joint Surface 12: Groove 13a-13e, 14a-14e: Half spacer 15: Bracket 16: Semi-fixed flange 17: Through hole 20: Export 21: Entrance 22: Lateral Half Wall 23: Inserts 24: Fixed components 25: Positioning components 26: Lateral positioning groove

Other advantages and features will become apparent upon reading the following description of specific, non-limiting embodiments of the invention and the accompanying drawings, wherein: [FIG. 1] is a view in an assembled state of the stator of the dry vacuum pump according to the first exemplary embodiment. [Fig. 2] It is a perspective view of an example of the rotor shaft of the vacuum pump of Fig. 1. [Fig. [Fig. 3] is a view of the stator in Fig. 1 with the half shell in disassembled state. [Fig. 4] is an exploded view of the stator of Fig. 3. [Fig. [Fig. 5] is a perspective view of the half shell of the stator of Fig. 1. [Fig. [Fig. 6] is a perspective view of another half-shell of the stator of Fig. 1. [Fig. [Fig. 7] is a perspective view of the two assembled detachable spacer halves. [Fig. 8] is a view of the assembled half-spacer in Fig. 7 rotated by 180 degrees. [Fig. 9A] shows a first variation of the second embodiment of the detachable half-shell, shown in cross section. [Fig. 9B] A view showing a second variation similar to Fig. 9A. [FIG. 10A] A view showing a third variant embodiment similar to FIG. 9A. [Fig. 10B] shows the half-shell of Fig. 10A in its disassembled state. [FIG. 11] is a top view of the half-shell of the dry vacuum pump according to the third exemplary embodiment. [Fig. 12] is a view of the half-shell cross section A-A of Fig. 11. [Fig. 13] is a front view of the half-spacer of the half-shell of Fig. 11. [Fig. In the figures, identical or similar elements have the same reference numerals.

2: Stator

3a-3f: Pumping stage

4: Suction port

5: Discharge port

7,8: half shell

9a-9e, 10a-10e: Interstage channel

11: Joint Surface

12: Groove

13e, 14a-14e: half spacer

15: Bracket

16: Semi-fixed flange

20: Export

22: Lateral Half Wall

Claims (20)

A dry vacuum pump (1), comprising: - a stator (2) comprising at least one first and at least one second complementary half-shell (7, 8), each half-shell (7, 8) comprising at least one spacer half (13a-13e), the at least one half-shell (7, 8) The spacers (13a-13e) are joined together with the spacers (14a-14e; 14) of the other half-shell (8), and are installed in series at the suction port (4) and discharge port ( 5) between the two successive pumping chambers of the pumping stages (3a-3f) forming a dividing spacer, - two rotor shafts (6) configured to rotate synchronously in opposite directions in the pumping chambers, Characterized in that the at least one half-spacer (13d, 13e, 14d, 14e; 14) of the half-shells (7, 8) is assembled to the bracket (15) of the half-shells (7, 8) by assembly middle. The vacuum pump (1) of claim 1, wherein the at least one half-spacer (13d, 13e, 14d, 14e) is assembled in the bracket (15) by detachable assembly. The vacuum pump (1) of claim 2, wherein the at least one partition half (13d, 13e, 14d, 14e) is fixed to the bracket (15) removably fitted in the half-shell (7, 8) The bottom half of the chamber with the at least one partition half (13d, 13e, 14d, 14e) is made in a removable insert (23) of the half shell (7, 8). The vacuum pump (1) of claim 2 or 3, wherein at least one half-shell (7, 8) comprises: - at least one removable fixing member (24), such as a screw, for fixing the removable half-spacer (13d, 13e, 14d, 14e) to the bracket (15), and/or - At least one positioning member (25), such as a pin or key, for positioning the removable half-spacer (13d, 13e, 14d, 14e) in the bracket (15). A vacuum pump (1) as claimed in claim 4, wherein the half-shells (7, 8) comprise at least one insert (23) carrying the at least one half-shell having a semi-fixed flange (16) Spacers (13d, 13e, 14d, 14e), the at least one fixing member (24) and/or the at least one positioning member (25) are for example axially inserted into the semi-fixed flange (16) and into the into the bracket (15) and/or into another fixing flange (16). The vacuum pump (1) of claim 5, wherein the at least one fixing member (24) and/or the at least one positioning member (25) are routed through the detachable half-spacer (13d, 13e, 14d, 14e) Insert into the bracket (15). The vacuum pump (1) of claim 2 or 3, wherein the vacuum pump (1) comprises at least one interstage channel (9e, 10e, 9d, 10d), the at least one interstage channel (9e, 10e, 9d, 10d) being The configuration is used to connect the outlet (20) of the previous pumping stage (3a-3e) to the inlet (21) of the next pumping stage (3b-3f), at least a part of the interstage half channel is made in the half shell In the insert (23) of (7, 8), and open on the side of the insert (23), the insert (23) carries the half-spacer (13d, 13e, 14d, 14e) and is detachable by assembled in the bracket (15). The vacuum pump (1) of claim 7, wherein the at least one interstage half-channel (9e, 10e, 9d, 10d) is formed on the side of the half-spacer (13d, 13e, 14d, 14e), in the semi-fixed In the flange (16), it also makes it possible to fix the insert (23) to the bracket (15). The vacuum pump (1) of claim 7, wherein the vacuum pump (1) comprises two inter-stage half-channels (9e, 10e, 9d, 10d), the two inter-stage half-channels (9e, 10e, 9d, 10d) being Partly formed in the sides of the at least one insert (23), the inter-stage channels (9e, 10e, 9d, 10d) are located on both sides of the half-spacer (13d, 13e, 14d, 14e). The vacuum pump (1) of claim 1, wherein at least one half-spacer (14) is assembled in the bracket (15) by means of press-fit fitting. The vacuum pump (1) of claim 10, wherein the vacuum pump (1) comprises at least one interstage channel (9e, 10e, 9d, 10d), the at least one interstage channel (9e, 10e, 9d, 10d) being structured To connect the outlet (20) of the previous pumping stage (3a-3e) to the inlet (21) of the next pumping stage (3b-3f), at least a part of the half-channel between stages is made in the half-shell (7 , 8) in the insert (23) and opening on the side of the insert (23), the insert (23) carries the half-spacer (14) and is assembled in the bracket by means of press fit (15). The vacuum pump (1) of any one of claims 1 to 3, wherein the at least one spacer half (13d, 13e, 14d, 14e; 14) assembled by assembly or an insert carrying the at least one spacer half The piece (23) is made of a material or coating, such as nickel, which is more resistant to corrosion and/or wear than the body material or coating of the half-shells (7, 8), such as cast iron. The vacuum pump (1) of any one of claims 1 to 3, wherein the at least one half-spacer (13d, 13e, 14d) is assembled by assembly in the bracket (15) of the half-shells (7, 8) , 14e) are joined together with at least one half-spacer (13d, 13e, 14d, 14e) also assembled by assembly in the bracket (15) of the other half-shell (7, 8). A vacuum pump (1) as claimed in any one of claims 1 to 3, wherein at least one half-shell (7, 8) comprises at least two half-spacers (13d, 13e) assembled by assembly, the at least two half-spacers (13d, 13e) The parts (13d, 13e) are joined together with two half-spacers (14d, 14e) assembled by assembling the other half-shell (8) to separate three successive pumping chambers (3d, 3e, 3f). A vacuum pump (1) as claimed in any one of claims 1 to 3, wherein the half-shells separating the last pumping stage (3f) from the pumping chambers of the penultimate pumping stage (3e) The half-spacers (13e, 14e; 14) of (7, 8) are assembled by assembly. The vacuum pump (1) of claim 15, wherein the half-shells (7, 8) separate the pumping chambers of the penultimate pumping stage (3e) from the pumping chambers of the third-to-last pumping stage (3d) ) of the half-spacers (13d, 14d; 14) are assembled by assembly. A vacuum pump (1) as claimed in any one of claims 1 to 3, wherein at least one half-shell (7, 8) comprises at least one half-spacer (13d, 13e, 14d, 14e) assembled by means of detachable assembly ) and at least one non-removable half-spacer (13a-13c, 14a-14c). The vacuum pump (1) of claim 17, wherein the at least one non-removable half-spacer (13a-13c, 14a-14c) is made with the mass of the half-shells (7, 8) or by means of press fit to be assembled in the bracket (15). The vacuum pump (1) of claim 17, wherein the half-spacer (13a-13c, 14a-14c) joined with the non-removable half-spacer (13a-13c, 14a-14c) is also non-removable . A method for manufacturing a dry vacuum pump (1), the dry vacuum pump (1) being the vacuum pump (1) as claimed in any one of claims 1 to 19, wherein at least one half spacer (13d) of the half shells (7, 8), 13e, 14d, 14e; 14) are fitted by detachable assembly in the brackets (15) of the half-shells (7,8), or are pressed into the brackets fitted in the half-shells (7,8) in the rack (15).

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