CN213779152U - Gas waist wheel flowmeter - Google Patents

Abstract

The embodiment of the invention discloses a gas waist wheel flowmeter, which is invented for reducing the pulsation phenomenon generated by the discharged instantaneous flow. The gas waist wheel flowmeter comprises more than two metering cavities; each metering cavity is respectively provided with a waist wheel set, and more than two waist wheel sets are arranged in parallel; more than two waist wheel sets are arranged in different relative metering positions in the metering cavities respectively. The embodiment of the invention is suitable for occasions for metering gases such as fuel gas and the like.

Description

Gas waist wheel flowmeter

Technical Field

The application relates to the technical field of flowmeters, in particular to a gas waist wheel flowmeter.

Background

The gas roots flowmeter is a metering instrument for continuously or intermittently measuring the flow of gas medium in pipeline, and has the features of high precision, high reliability, long service life, convenient installation and use, etc. and is typical of positive displacement flowmeter. With the construction and popularization of gas transmission pipelines, the waist wheel flowmeter is widely applied to the fields of industrial and commercial trade metering and standard checking due to the advantages of high precision, good repeatability and the like.

The existing gas roots flowmeter is basically in a single group of roots and shell combination form, when the flowmeter with the structure is used on site, instantaneous flow discharged in normal operation shows sinusoidal fluctuation along with different rotation angles of the roots, namely, pulsation exists, so that the repeatability of the flowmeter is poor, and the flowmeter cannot be applied to occasions with high precision requirements.

Disclosure of Invention

In view of the above, embodiments of the present application provide a gas roots meter, which can reduce the pulsation phenomenon caused by the instantaneous flow rate of the exhaust gas.

The embodiment of this application provides a gaseous roots flowmeter includes: more than two metering cavities, wherein each metering cavity is provided with a waist wheel set, and the more than two waist wheel sets are arranged in parallel; more than two waist wheel sets are arranged in different relative metering positions in the metering cavities respectively.

According to a specific implementation manner of the embodiment of the present application, the two or more metering chambers are located in the same cavity; and air inlets are respectively arranged at the positions corresponding to the metering cavities on the cavity body.

According to a specific implementation manner of the embodiment of the application, a common exhaust channel communicated with the exhaust ports of the at least two metering cavities is arranged in the cavity, extends along the length direction of the cavity and is communicated with the air outlet at one end of the cavity.

According to a specific implementation manner of the embodiment of the application, an inter-group linkage mechanism is arranged between more than two waist wheel sets.

According to a specific implementation manner of the embodiment of the application, each waist wheel set comprises a first rotor and a second rotor matched with the first rotor, and the inter-group linkage mechanism is connected with the first rotor or the second rotor of more than two waist wheel sets.

According to a specific implementation manner of the embodiment of the application, the inter-group linkage mechanism is arranged outside the cavity and is connected with the end parts of the first rotor or the second rotor of more than two waist wheel groups.

According to a specific implementation manner of the embodiment of the application, a first end of the first rotor of each waist wheel set is connected with a first gear, a first end of the second rotor of each waist wheel set is connected with a second gear, and the first gear and the second gear are the same in size and are meshed with each other;

the inter-group linkage mechanism is meshed with first gears connected with the first rotors of the more than two waist wheel sets, or meshed with second gears connected with the second rotors of the more than two waist wheel sets.

According to a specific implementation manner of the embodiment of the application, the inter-group linkage mechanism is a gear linkage mechanism or a synchronous belt.

According to a specific implementation manner of the embodiment of the application, the gear linkage mechanism comprises a group of inter-group linkage gears, and the inter-group linkage gears are rotatably arranged outside the cavity and meshed with first gears connected with first rotors of more than two waist wheel groups or meshed with second gears connected with second rotors of more than two waist wheel groups;

alternatively, the first and second electrodes may be,

the gear linkage mechanism comprises a main linkage gear which is rotatably arranged outside the cavity, an intermediate gear is arranged between the main linkage gear and a first gear connected with first rotors of more than two waist wheel sets, and the intermediate gear is meshed with the main linkage gear and the first gear; or an intermediate gear is arranged between the main linkage gear and second gears connected with second rotors of more than two waist gear sets, and the intermediate gear is meshed with the main linkage gear and the second gears;

alternatively, the first and second electrodes may be,

the gear linkage mechanism comprises a gear ring which is arranged outside the cavity and is meshed with first gears connected with first rotors of more than two waist wheel sets or meshed with second gears connected with second rotors of more than two waist wheel sets.

According to a specific implementation of the embodiment of the present application, each of the sets of pulleys includes a first rotor and a second rotor cooperating with the first rotor;

in each waist wheel set, along the clockwise or anticlockwise direction, in n first rotors from the first rotor of the 1 st waist wheel set to the first rotor of the nth waist wheel set, the included angle between the first rotors of the adjacent waist wheel sets is increased in a preset angle gradient manner; the first rotor of each waist wheel set is one of the two rotors of each waist wheel set, and the rotor is positioned in the same installation position along the clockwise direction or the anticlockwise direction;

the predetermined angular gradient is determined according to the following formula:

k＝90°/n±5°：

wherein k is a predetermined angular gradient;

n is the number of the waist wheel groups.

According to a specific implementation manner of the embodiment of the present application, the two or more metering chambers are two, three, or four metering chambers.

According to a specific implementation manner of the embodiment of the application, a partition wall between two adjacent metering chambers is of a symmetrical structure relative to a symmetrical center plane between the two adjacent metering chambers; the symmetry center plane passes through the central axis of the cavity;

alternatively, the first and second electrodes may be,

the partition wall between two adjacent metering chambers is in an asymmetric structure relative to the symmetric center plane between the two adjacent metering chambers. The central symmetry plane passes through the central axis of the cavity.

According to a specific implementation manner of the embodiment of the application, the gas waist wheel flowmeter further comprises a shell, wherein the metering module is detachably arranged in the shell; the metering module comprises a cavity body with a metering cavity inside and a waist wheel set in each metering cavity;

the shell is provided with a first air inlet and a first air outlet which are communicated with an external air flow conveying pipeline;

the shell is internally provided with a first flow guide channel communicated with the first air inlet and the air inlets of the metering cavities, and a second flow guide channel communicated with the air outlet of the cavity and the first air outlet.

According to a specific implementation manner of the embodiment of the application, the shell comprises a shell body, the shell body is provided with an opening for taking and placing the metering module, and a cover body is covered at the opening; the metering module is arranged in the shell body; the first air inlet and the first air outlet are arranged on the shell body.

According to a specific implementation manner of the embodiment of the application, the shell body comprises a pipeline connecting part and a metering module accommodating part;

an airflow buffer cavity and an airflow discharge cavity are arranged in the pipeline connecting part, and the airflow buffer cavity is isolated from the airflow discharge cavity; the first air inlet and the first air outlet are arranged on the pipeline connecting part; the airflow buffer cavity is respectively communicated with the first air inlet and the air inlets of the metering cavities, and the airflow discharge cavity is respectively communicated with the air outlet of the cavity and the first air outlet;

the measurement module holds and has the measurement module in the portion and hold the chamber, the measurement module is established the measurement module holds in the chamber.

According to a specific implementation manner of the embodiment of the present application, the airflow discharging cavity is a cylindrical structure extending along the central axis of the housing, and the airflow buffering cavity is an incomplete annular body structure surrounding the airflow discharging cavity.

According to a specific implementation manner of the embodiment of the application, the air inlet of each metering cavity is arranged on the side wall of the cavity, and a preset gap is formed between the inlet of the air inlet of each metering cavity and the inner wall of the accommodating cavity of the metering module; the airflow buffer cavity is communicated with the preset gap, and the airflow buffer cavity and the metering module accommodating cavity form the first flow guide channel.

According to a specific implementation mode of this application embodiment, the gas outlet department of cavity is connected with the transition connecting pipe, the transition connecting pipe certainly the gas outlet department of cavity extends to in the air current discharge chamber, the transition connecting pipe with the air current discharge chamber forms second water conservancy diversion passageway.

According to one embodiment of the present disclosure, a fluid filter is disposed within the housing between the outlet of the airflow buffer chamber and the inlet of each metering chamber.

According to a specific implementation manner of the embodiment of the application, the metering module accommodating cavity is respectively communicated with the airflow buffer cavity and the airflow discharge cavity;

the metering module accommodating cavity is communicated with the airflow buffer cavity and is provided with a step, the fluid filter member is supported on the step, and the metering module is supported on the fluid filter member.

According to a specific implementation manner of the embodiment of the application, the fluid filter element comprises an annular bracket, wherein the side wall of the bracket is provided with a filter hole, and a filter screen is arranged on the bracket at a position corresponding to the filter hole; wherein the bracket is supported on the step.

According to a specific implementation manner of the embodiment of the application, a bypass opening which can conduct the first flow guide channel and the second flow guide channel is arranged on the side wall of the transition connecting pipe, and a pressure difference switch piece is arranged at the bypass opening.

According to a specific implementation mode of this application embodiment, pressure differential switch spare includes fixed connector and elasticity action, fixed connector establishes on the transition connection pipe, the elasticity action is established fixed connector is last to will when being in free state the bypass opening seals.

In the embodiment of the application, the two or more metering cavities are respectively provided with the waist wheel set, so that the metering can be simultaneously carried out in the plurality of metering cavities, the gas volume passing through the flowmeter in unit time can be increased, and the throughput of the flowmeter is improved. The waist wheelset in the measurement chamber more than two, the relative measurement position that is in the measurement chamber at place separately is different for each measurement chamber can stagger peak exhaust air current, and the crest or the trough of each measurement chamber combustion gas flow can stagger each other promptly, and like this, each measurement chamber combustion gas flow joins the back and is comparatively gentle from the pulsation of flowmeter combustion gas flow, can effectively alleviate the pulsation phenomenon of flowmeter combustion gas flow, thereby makes the repeatability of flowmeter better.

Drawings

In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below, it is obvious that the drawings in the following description are only some embodiments of the present application, and other drawings can be obtained by those skilled in the art without creative efforts.

FIG. 1 is a schematic diagram of an explosive structure of a gas Roots flowmeter according to an embodiment of the invention;

FIG. 2 is a schematic cross-sectional view of a gas Roots flowmeter according to an embodiment of the invention;

FIG. 3 is a schematic view of the internal structural arrangement of a gas Roots flowmeter according to an embodiment of the invention;

FIG. 4 is a schematic diagram of the gas Roots flowmeter chamber of FIG. 3;

FIG. 5 is a schematic view of a layout structure of a waist wheel set according to an embodiment of the present invention;

FIG. 6 is a schematic view of a linkage arrangement according to an embodiment of the present invention;

FIG. 7 is a schematic view of a linkage arrangement according to another embodiment of the present invention;

FIGS. 8 and 9 are schematic views of linkage arrangements according to another embodiment of the present invention;

FIG. 10 is a schematic view of a linkage arrangement according to yet another embodiment of the present invention;

FIG. 11a is a schematic view of a layout of a lumbar group according to another embodiment of the present invention;

FIG. 11b is a schematic view of a waist wheel set layout according to another embodiment of the present invention;

FIG. 12 is a schematic view of a layout of a waist wheel set according to still another embodiment of the present invention;

FIG. 13 is a schematic view of a gas roots meter with a housing according to another embodiment of the invention;

FIG. 14 is a cross-sectional schematic view of a gas roots meter with a housing according to an embodiment of the invention;

FIG. 15 is a schematic flow diagram of a gas flow metering method according to an embodiment of the present invention;

FIGS. 16a and 16b are schematic views illustrating the flow of gas in the gas flow measuring method according to the embodiment of the present invention;

FIG. 17 is a schematic view of the gas flow direction in a gas flow measurement method according to another embodiment of the present invention.

Detailed Description

The embodiments of the present application will be described in detail below with reference to the accompanying drawings. It should be understood that the embodiments described are only a few embodiments of the present application, and not all embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present application.

The embodiment of the invention provides a gas roots flowmeter, comprising: more than two metering cavities, wherein each metering cavity is provided with a waist wheel set, and more than two waist wheel sets are arranged in parallel; the relative metering positions of the waist wheel sets in the metering cavities in which the waist wheel sets are respectively positioned are different.

Wherein, the more than two metering cavities can be two, three or four or more metering cavities.

In the embodiment, the gas can be simultaneously metered in the metering cavities, so that the volume of the gas passing through the flowmeter in unit time can be increased, and the throughput of the flowmeter is improved. The waist wheel sets in the more than two metering cavities are different in relative metering positions in the metering cavities, the throughput of the flowmeter is provided, meanwhile, the pulsation phenomenon of the gas flow discharged by the flowmeter can be reduced, and therefore the repeatability of the flowmeter is good. The embodiment of the invention can be used for metering gases such as fuel gas and the like.

Referring to fig. 1 to 3, an embodiment of the present invention provides a gas waist wheel flowmeter, including three metering chambers 10, a waist wheel set 20 is respectively disposed in each metering chamber 10, and the waist wheel sets 20 in the three metering chambers 10 are disposed in parallel; the lumbar wheel sets 20 in the three metering chambers 10 are located at different relative metering positions in the respective metering chambers. The three metering chambers in fig. 1 are 10a, 10b, 10c, respectively.

The lumbar group 20 in each metering chamber 10 may include a first rotor 201 and a second rotor 202 cooperating with the first rotor 201. When the three lumbar gear sets 20 are arranged in parallel, the planes of the rotation center lines of the first rotor 201 and the second rotor 202 in one of the lumbar gear sets and the planes of the rotation center lines of the first rotor 201 and the second rotor 202 in the other lumbar gear sets are not on the same plane. The rotation center line of the first rotor 201 is the rotation shaft center line of the first rotor 201, and the rotation center line of the second rotor 202 is the rotation shaft center line of the second rotor 202.

The relative metering position of the lumbar gear set 20 in the metering chamber may be the relative position of a rotor (such as the first rotor) in the same mounting sequence in the metering chamber, which is located in the metering chamber, of the three lumbar gear sets 20.

The lumbar wheel sets 20 in the three metering chambers 10 are located at different relative metering positions in the respective metering chambers. For example, the lumbar wheel sets 20 in the three metering chambers 10 may be disposed at different angles with respect to the air inlets of the respective metering chambers 10, in one example, the lumbar wheel sets 20 in the three metering chambers 10 may be disposed at different angles with respect to the air inlets of the respective metering chambers 10, specifically, the lumbar wheel sets 20 in the three metering chambers 10 are disposed at different angles with respect to the air inlet directions of the air inlets of the respective metering chambers 10. The maximum longitudinal section of any rotor in the lumbar gear set 20 may be set at different angles relative to the air intake direction of the air inlet of the metering chamber 10, and the maximum longitudinal section of a rotor is the maximum longitudinal section passing through the central axis of the rotor.

In other embodiments, the groups of the lumbar wheels 20 in the three metering chambers 10 may be disposed at different angles with respect to the plane where the air inlet end or the air outlet end of the air inlet of the respective metering chamber 10 is located. The maximum longitudinal section of any rotor in the lumbar gear set 20 may be set at different angles relative to the plane where the air inlet end or the air outlet end of the air inlet of the metering cavity 10 is located.

The gas enters each metering cavity 10 from the gas inlet of each metering cavity 10, the pressure difference existing outside and inside the metering cavity 10 pushes the waist wheel set 20 to rotate, and the gas flows out of each metering cavity 10 from the gas exhaust side (also called as gas exhaust end or gas exhaust port) of each metering cavity 10 after passing through the metering cavity 10. Gas flow through the meter can be metered by counting the number of revolutions of the rotor in each of the groups 20 (e.g., the number of revolutions of the rotor can be counted by a sensor disposed at the end of the rotor) in combination with the amount of gas flow through the metering chamber 10 during one revolution of the rotor.

In this embodiment, three metering chambers 10 are provided in the chamber, and a waist wheel set 20 is provided in each metering chamber 10, so that the gas volume passing through the flow meter in unit time can be increased by metering through the three metering chambers 10, and the throughput of the flow meter can be improved.

The gas flow of single measurement chamber 10 exhaust has the condition of pulsation, adjacent three measurement chamber 10 that is provided with in this embodiment, and the roots wheel group 20 in three measurement chamber 10, the relative measurement position that is in the measurement chamber at place respectively is different, make each measurement chamber can the wrong peak exhaust air current, the crest or the trough of each measurement chamber exhaust gas flow can stagger each other promptly, like this, the pulsation from the flowmeter exhaust air current after each measurement chamber exhaust air current converges is comparatively gentle, can effectively alleviate the pulsation phenomenon of flowmeter exhaust gas flow, thereby make the repeatability of flowmeter better. The repeatability of the flowmeter refers to the difference of the gas flow measured by the flowmeter in different time periods, and the smaller the difference is, the better the repeatability of the flowmeter is.

The waist wheel sets 20 in more than two metering cavities 10 are arranged in parallel, that is, more than two metering cavities 10 are arranged in parallel, so that the arrangement of each metering cavity 10 is relatively compact, the volume of the flowmeter is relatively small, the air flows discharged by each metering cavity 10 can be rapidly converged, the air flows discharged by each metering cavity 10 can be converged only by a short flow path, and the pulsation phenomenon of the air flow discharged by the flowmeter can be eliminated or reduced earlier or more rapidly.

Referring to fig. 3-4, for ease of assembly, in one example, more than two metering chambers 10 may be located within the same chamber 30, or more than two metering chambers 10 may be located within the same chamber 30; the cavity 30 is provided with air inlets 301 at positions corresponding to the respective measuring chambers 10.

Referring to fig. 2 and 3, an air outlet 302 is provided on the chamber 30, and the air outlet 302 is communicated with the air outlet of each metering chamber 10. In another example, there may be a plurality of air outlets in the chamber 30, one for each metering chamber 10. In addition to having more than two metering chambers 10 within the same chamber body 30, in other embodiments, a single metering chamber or chambers may be provided in addition to the chamber body 30, and the single metering chamber or chambers may be used in conjunction with more than two metering chambers within the same chamber body 30.

The cavity 30 may also be referred to as a mold cavity. In one example, the cavity is provided with a common exhaust passage communicated with the exhaust ports of at least two metering cavities, and the common exhaust passage extends along the length direction of the cavity and is communicated with the air outlet at one end of the cavity.

Referring to fig. 4, the cavity 30 may be hollow and cylindrical, that is, the middle of the cavity 30 has a hollow structure 303, and the metering cavity 10 and the lumbar group 20 extend along the length direction of the cavity 30, so as to increase the volume of the metering cavity 10. The three metering cavities 10 are arranged around the central axis of the cavity 30, and the hollow structure 303 in the middle of the cavity 30 is communicated with the exhaust side of each metering cavity 10, so that the hollow structure 303 in the middle of the cavity 30 becomes a common exhaust channel of each metering cavity 10, and the common exhaust channel is communicated with the air outlet 302 of the flowmeter, namely the air outlet 302 is communicated with the hollow structure 303 in the middle of the cavity 30. The common exhaust passage is located in the middle of the chamber 30 and is communicated with the airflow exhaust port of each metering chamber 10, and the airflow exhausted from each metering chamber 10 can be merged by the shortest possible flow path, or the airflow can be merged after being exhausted from each metering chamber 10, so that the pulsation phenomenon of the airflow exhausted by the flowmeter can be eliminated or reduced earlier or faster.

Referring to fig. 1 and 3, the chamber body 30 may include a chamber body 304 having openings at both ends, a first end plate 305 disposed at a first end of the chamber body 304, and a second end plate 306 disposed at a second end; the air inlet is arranged on the cavity body 304, and the air outlet 302 is arranged on the second end plate 306; each metering chamber 10 in the cavity 30 may include a first metering chamber 304a and a second metering chamber 304b surrounded by walls, the first metering chamber 304a and the second metering chamber 304b being disposed opposite to each other. In one example, the first and second metering chambers 304a, 304b may each be semi-circular in cross-section.

The lumbar group 20 in each metering chamber 10 may include a first rotor 201 and a second rotor 202 cooperating with the first rotor 201. The first rotor 201 and the second rotor 202 are long structures with 8-shaped cross sections.

The radius of rotation of the first rotor 201 may be the same as the radius of a semicircle formed by the cross-section of the first metering chamber 304 a; the radius of rotation of the second rotor 202 may be the same as the radius of the semicircle formed by the cross-section of the second metering chamber 304 b; wherein the second rotor 202 is the same size as the first rotor 201.

The first and second rotors 201, 202 of each lumbar group 20 have first ends rotatably mounted to a first end plate 305 and second ends rotatably mounted to a second end plate 306. Bearings may be provided at the locations where the first and second rotors 201, 202 are rotatably coupled to the first and second end plates 305, 306.

In one example, an end cap 307 is disposed outside the second end plate 306, and the end cap 307 is connected to the second end plate 306; a through hole is formed in the end cover 307, a transition connecting pipe 308 is connected to the air outlet 302, and the transition connecting pipe 308 extends out of the through hole in the end cover 307. Between the end cover 307 and the second end plate 306, there is a receiving space which can store lubricating oil for providing lubrication to the second ends of the first rotor 201 and the second rotor 202, and in addition, the end cover 307 and the transition connection pipe 308 cooperate to prevent the gas discharged from the gas outlet 302 from adversely affecting the rotating connection structure (such as a bearing, etc.) between the second ends of the first rotor 201 and the second rotor 202 and the second end plate 306.

In order to improve the accuracy of the metering, a linkage mechanism may be disposed between the first rotor 201 and the second rotor 202 to link the rotation of the first rotor 201 and the second rotor 202, and the linkage mechanism between the first rotor 201 and the second rotor 202 may be referred to as an intra-group linkage mechanism. The in-group linkage mechanism can be a gear linkage mechanism or a synchronous belt linkage mechanism and the like.

Referring to fig. 5, the sets of lumbar wheels 20 in the three metering chambers 10 are disposed at different angles with respect to the air inlets of the respective metering chambers 10. In each of the lumbar gear sets 20, in the clockwise direction, the included angle of the first rotor of the adjacent lumbar gear set 20 with respect to the air inlet of the metering chamber 10 in each of the 3 first rotors (201a, 201b, 201c) from the first rotor 201a of the 1 st lumbar gear set 20 to the first rotor 201c of the 3 rd lumbar gear set 20 increases in an angle gradient of 30 ° ± 5 °; the first rotor of each of the lumbar gear sets 20 is one of the two rotors of each of the lumbar gear sets 20, which is located in the first installation order along the clockwise direction. In fig. 5, the first rotor 201a, the first rotor 201b, and the first rotor 201c are one rotor in the first mounting order in the clockwise direction.

The included angle of the first rotor 201 of the adjacent waist wheel set 20 with respect to the air inlet of the metering chamber 10 where the first rotor 201 is located is specifically the included angle of the maximum longitudinal section passing through the rotation central axis of the first rotor 201 with respect to the air inlet direction of the air inlet of the metering chamber 10 where the first rotor 201 is located.

Referring to fig. 5, in one example, the angles of the first rotors 201 of the adjacent waist wheel sets 20 with respect to the air inlets of the respective metering chambers 10 are gradually increased by an angle gradient of 30 °.

In other embodiments, in each of the lumbar gear sets 20, the included angle between the first rotors of the adjacent lumbar gear sets 20 increases in a predetermined angular gradient in the clockwise direction from the first rotor 201a of the 1 st lumbar gear set 20 to the 3 first rotors (201a, 201b, 201c) of the first rotor 201c of the 3 rd lumbar gear set 20. The angle between the first rotors of the adjacent lumbar gear sets 20 may refer to an angle between a maximum longitudinal section passing through a rotation axis center line of the first rotor of one lumbar gear set and a maximum longitudinal section passing through a rotation axis center line of the first rotor of the other lumbar gear set.

In order to ensure that the lumbar wheel sets 20 in the three metering chambers 10 have relatively stable relative positions during the metering process, and further reduce the pulsation phenomenon of the gas flow discharged by the flow meter, referring to fig. 6 to 10, in one example, an inter-set linkage mechanism 40 is arranged between the lumbar wheel sets 20 in the three metering chambers 10, so that the rotation of the lumbar wheel sets 20 in the three metering chambers 10 is linked, and the total gas discharge amount after the gas flow discharged by each metering chamber 10 is superposed can be kept relatively stable in any time period.

Referring to FIG. 6, in one example, inter-group linkage 40 is coupled to first rotor 201 of each lumbar group 20.

The inter-group linkage 40 may be disposed outside the cavity 30 and coupled to the ends of the first rotors 201 of the two or more sets of lumbar gears. In one example, a first gear 2011 is connected to a first end of the first rotor 201 of each waist wheel set, a second gear 2012 is connected to a first end of the second rotor 202 of each waist wheel set, and the first gear 2011 and the second gear 2012 are the same in size and are meshed with each other; the inter-group link mechanism is engaged with the first gear 2011 connected to the first rotors 201 of the two or more lumbar groups.

For example, referring to fig. 1, inter-group linkage 40 is disposed outside first end plate 305 and is coupled to an end of first rotor 201 of each of lumbar groups 20; the outer side of the first end plate 305 is the side of the first end plate 305 facing away from the lumbar wheel set 20.

Two ends of the first rotor 201 and the second rotor 202 of each waist wheel set 20 are respectively provided with a rotating shaft; a rotating shaft at the first end of the first rotor 201 of each lumbar gear set 20 penetrates through a through hole in the first end plate 305 and is connected with a first gear 2011, a rotating shaft at the first end of the second rotor 202 of each lumbar gear set 20 penetrates through a through hole in the first end plate 305 and is connected with a second gear 2012, the first gear 2011 and the second gear 2012 are the same in size and are meshed with each other, and the first gear 2011 and the second gear 2012 form an in-set linkage mechanism; the inter-group link mechanism 40 is engaged with the first gear 2011 connected to the first rotor 201 of each of the respective lumbar gear groups 20.

Inter-group linkage 40 may be a gear linkage. Referring to fig. 6, inter-group linkage 40 specifically includes a main linkage 401a, and an intermediate gear 402a is provided between main linkage 401a and first gear 2011 to which first rotor 201 of each of lumbar gear sets 20 is connected, intermediate gear 402a meshing with main linkage 401a and first gear 2011.

The present embodiment is not limited to this, and in another embodiment, an intermediate gear 402a is provided between the main link gear 401a and the second gear 2012 connected to the second rotor 202 of each of the lumbar gear sets 20, and the intermediate gear 402a meshes with the main link gear 401a and the second gear 2012.

In this embodiment, the main link gear 401a is rotatably provided at a central position outside the first end plate 305, and is engaged with the first gear 2011 connected to the first rotor 201 of each of the lumbar gear sets 20 via the intermediate gear 402a, but is not engaged with the second gear 2012 connected to the second rotor 202 of each of the lumbar gear sets 20. In this case, the distances from the rotation centers of the first rotor 201 and the second rotor 202 to the rotation center of the main link gear 401a may be the same, so that the partition wall between the adjacent two metering chambers 10 has a symmetrical structure with respect to the symmetrical center plane between the adjacent two metering chambers 10; the center plane of symmetry passes through the central axis of the cavity 30.

Referring to fig. 7, as an alternative arrangement of the intermediate gear 402a, the intermediate gear 402a may be replaced by an intermediate gear 402b coaxially associated with the second rotor 202 of each of the lumbar gear sets 20, the intermediate gear 402b forming a double gear with the first rotor 202 of each of the lumbar gear sets 20.

In this embodiment, the air outlet 302 is formed on the second end plate 306, and in other embodiments, the air outlet 302 may be formed on the first end plate 305.

In this embodiment, the inter-group linkage 40 is disposed outside the first end plate 305, but in other embodiments, the inter-group linkage 40 may be disposed outside the second end plate 306, and the outside of the second end plate 306 is the side of the second end plate 306 facing away from the lumbar gear set 20. In this embodiment, the inter-group linkage 40 is coupled to an end of the first rotor 201 of each of the pinwheel groups 20, and in other embodiments, the inter-group linkage 40 may be coupled to an end of the second rotor 202 of each of the pinwheel groups 20.

Fig. 8 and 9 are schematic views showing an inter-group interlocking mechanism of a gas Roots flowmeter according to another embodiment of the present invention, and referring to fig. 8 and 9, the mechanism of the present embodiment is substantially the same as the structure of the embodiment shown in fig. 1, except that in the present embodiment, the gear interlocking mechanism includes an inter-group interlocking gear 401b, and the inter-group interlocking gear 401b is rotatably provided outside the first end plate 305 and meshes with a first gear 2011 to which the first rotor 201 of each Roots 20 is connected. Inter-group interlocking gear 401b does not mesh with second gear 2012 connected to second rotor 202 of each of the lumbar gear sets 20.

In this embodiment, inter-group interlocking gear 401b is rotatably provided at a central position outside first end plate 305, and directly engages with first gear 2011 connected to first rotor 201 of each of lumbar gear sets 20, but does not engage with second gear 2012 connected to second rotor 202 of each of lumbar gear sets 20. In this case, the distances from the rotation centers of the first rotor 201 and the second rotor 202 to the rotation center of the inter-group interlocking gear 401b are different, so that the partition wall between the adjacent two metering chambers 10 may be asymmetrical with respect to the center plane of symmetry between the adjacent two metering chambers 10. The center plane of symmetry passes through the central axis of the cavity 30.

Fig. 10 is a schematic view of an inter-group linkage mechanism of a gas Roots flowmeter according to another embodiment of the present invention, and referring to fig. 10, the mechanism of this embodiment is substantially the same as the structure of the embodiment shown in fig. 1, except that, in this embodiment, the inter-group linkage mechanism 40 includes a ring gear 401c, which is disposed outside the first end plate 305 and meshes with a first gear 2011 to which the first rotor 201 of each Roots 20 is connected.

The present embodiment is not limited thereto, and in other embodiments, the ring gear 401c may also mesh with the second gear 2012 connected to the second rotor 202 of each of the lumbar gear sets 20.

In another embodiment, the ring gear 401c may be replaced with a synchronous belt.

Fig. 11a is a schematic structural diagram of a gas roots flowmeter according to another embodiment of the present invention, fig. 11b is a schematic structural diagram of a gas roots flowmeter according to yet another embodiment of the present invention, and referring to fig. 11a and fig. 11b, the mechanism of this embodiment is substantially the same as the structure of the embodiment shown in fig. 1, except that in this embodiment, four metering chambers 10 are provided in a chamber 30, a waist wheel group 20 is provided in each metering chamber 10, and four waist wheel groups 20 in the four metering chambers 10 are provided in parallel; similar to the embodiment having three metering chambers 10 in the chamber 30, in the present embodiment, in each of the lumbar wheel sets 20, in the clockwise direction, the included angle of the first rotor 201 of the adjacent lumbar wheel set 20 with respect to the air inlet of the respective metering chamber 10 is increased by an angular gradient of 22.5 ° ± 5 ° in the 4 first rotors 201 from the first rotor 201 of the 1 st lumbar wheel set 20 to the first rotor 201 of the 4 th lumbar wheel set 20; the first rotor 201 of each of the sets of pinions 20 is one of the two rotors of each of the sets of pinions 20, which is located in the first installation order in the clockwise direction.

In fig. 11a, the distances from the rotation centers of the first rotor and the second rotor to the rotation center of the inter-group interlocking gear are the same, so that the partition wall between the two adjacent metering chambers may have a symmetrical structure with respect to the plane of symmetry between the two adjacent metering chambers. The symmetry center plane passes through the center axis of the cavity.

In fig. 11b, the distances from the rotation centers of the first rotor and the second rotor to the rotation center of the inter-group interlocking gear are the same, so that the partition wall between the two adjacent metering chambers may have a symmetrical structure with respect to the plane of symmetry between the two adjacent metering chambers. The symmetry center plane passes through the center axis of the cavity.

In the above embodiments, there are three or four metering chambers 10 in the chamber body 30. Embodiments of the present invention are not limited in this regard and other numbers of metering chambers 10, such as two (as shown in fig. 12), five, six, etc., may be provided within the chamber body 30. When a plurality of metering cavities 10 are arranged in the cavity 30, each waist wheel set 20 comprises a first rotor 201 and a second rotor 202 matched with the first rotor 201; the arrangement angle of the rotor of each of the lumbar groups 20 can be determined as follows:

in each of the lumbar gear sets 20, along a clockwise direction or a counterclockwise direction, in n first rotors 201 from the first rotor 201 of the 1 st lumbar gear set 20 to the first rotor 201 of the nth lumbar gear set 20, an included angle between the first rotor 201 of the adjacent lumbar gear set 20 and an air inlet (specifically, an air inlet direction of the air inlet) of the metering cavity 10 where the first rotor is located is increased in a predetermined angle gradient; wherein, the first rotor 201 of each of the lumbar gear sets 20 is one of the two rotors of each of the lumbar gear sets 20, which is in the same installation order along the clockwise or counterclockwise direction;

the predetermined angular gradient is determined according to the following formula:

k＝90°/n±5°；

wherein k is a predetermined angular gradient;

n is the number of the waist wheel groups. n may be a natural number of 2 or more and 8 or less.

Fig. 13 is a schematic structural diagram of a gas roots flowmeter according to another embodiment of the present invention, fig. 14 is a schematic sectional structural diagram of a gas roots flowmeter according to another embodiment of the present invention, and referring to fig. 13 and fig. 14, the mechanism of the present embodiment is substantially the same as the structure of the embodiment shown in fig. 1, except that the gas roots flowmeter further includes a housing 50, and a metering module is detachably disposed in the housing 50. Wherein, the metering module comprises a cavity 30 with three metering cavities 10 therein and a waist wheel group 20 in each metering cavity 10.

The shell 50 is provided with a shell air inlet 501 (hereinafter referred to as a first air inlet) and a shell air outlet 502 (hereinafter referred to as a first air outlet) which are communicated with an external air flow conveying pipeline; a first flow guide passage communicating the first gas inlet and the gas inlet of each metering chamber 10 (hereinafter referred to as a second gas inlet) and a second flow guide passage communicating the gas outlet 302 on the chamber body 30 (hereinafter referred to as a second gas outlet) and the first gas outlet are provided in the housing 50.

In this embodiment, the metering module is detachably arranged in the casing 50, and when the metering module fails, the metering module can be detached from the casing 50 for quick maintenance or replacement, so that the influence on normal production and life of downstream users, caused by the metering module failure in the waist-wheel flowmeter, can be reduced conveniently.

In one example, the housing 50 includes a housing body 503, the housing body 503 has an opening for accessing the metering module, and a cover 504 covers the opening; wherein the housing body 503 comprises a conduit connection portion 5031 and a metering module housing portion 5032; an air flow buffer cavity 50311 and an air flow discharge cavity 50312 are arranged in the pipeline connecting part 5031, and the air flow buffer cavity 50311 is separated from the air flow discharge cavity 50312; the first gas inlet and the first gas outlet are arranged on the pipeline connecting part 5031 and are used for being connected with an external gas conveying pipeline; the air flow buffer cavity 50311 is respectively communicated with the first air inlet and the second air inlet, and the air flow discharge cavity 50312 is respectively communicated with the second air outlet and the first air outlet; the metering module accommodating portion 5032 has a metering module accommodating cavity therein, and the metering module is disposed in the metering module accommodating cavity.

The gas flow buffer cavity 50311 can buffer the incoming gas. When the fluid contains impurities, such as welding slag and other larger particles, and the fluid enters the gas flow buffer cavity 50311, a portion of the impurities in the fluid may be precipitated in the gas flow buffer cavity 50311 due to the influence of gravity.

In one example, the gas flow discharge cavity 50312 is a cylindrical structure extending along the central axis of the housing 50, and the gas flow buffer cavity 50311 is an incomplete annular structure surrounding the gas flow discharge cavity 50312 and having a large buffer space.

A linkage mechanism accommodating cavity a is formed between the cover 504 and the first end plate 305 of the metering module, and the inter-group linkage mechanism 40 is positioned in the linkage mechanism accommodating cavity a, so that adverse effects of corrosion and the like of the metering gas on the inter-group linkage mechanism 40 can be reduced.

In one example, the second air inlet is provided on a side wall of the cavity 30, and a predetermined gap b is provided between an inlet of the second air inlet and an inner wall of the metering module accommodating cavity; the air flow buffer cavity 50311 is communicated with the predetermined gap b, and the air flow buffer cavity 50311 and the metering module accommodating cavity form the first flow guide channel.

The predetermined gap b between the inlet of the second air inlet and the inner wall of the metering module accommodating cavity can further buffer the air flow, and after the air flow enters the metering module accommodating cavity from the air flow buffer cavity 50311, the air flow can enter each metering cavity 10 more smoothly through the predetermined gap b.

In one example, a fluid filter 60 is disposed in the housing 50 between the outlet of the air flow buffering cavity 50311 and the second air inlet to filter the impurities in the fluid and prevent the impurities in the air flow from entering the metering cavity 10 to affect or even block the rotation of the rotor in the pulley set 20.

The metering module accommodating cavity is respectively communicated with the airflow buffer cavity 50311 and the airflow discharge cavity 50312; there is a step where the metering module receiving cavity communicates with the airflow buffer cavity 50311, the fluid filter 60 is supported on the step, and the metering module is supported on the fluid filter 60.

In one example, the fluid filter element 60 includes a ring-shaped bracket, a filter hole is opened on a side wall of the bracket, and a filter screen is arranged on the bracket at a position corresponding to the filter hole; wherein the bracket is supported on the step. One end of the support flow can be hermetically connected with the bottom of the metering module, and the other end of the support flow is hermetically connected with the step surface of the step.

In one example, a transition connection tube 308 is connected to the air outlet of the cavity 30, the transition connection tube 308 extends from the air outlet of the cavity 30 to the air flow discharge cavity 50312, and the transition connection tube 308 and the air flow discharge cavity 50312 form the second flow guiding channel. The transition connection tube 308 passes through the central portion of the stent.

After entering the airflow buffer cavity 50311 from the first air inlet, the external airflow enters the predetermined gap b in the metering module accommodating cavity through the fluid filter 60, enters each metering cavity 10 through the second air inlet at the predetermined gap b, passes through each metering cavity 10, is collected into a common exhaust channel formed by the hollow structure 303 in the middle of the cavity 30, enters the transition connecting pipe 308 through a second air outlet communicated with the common exhaust channel, is guided to the airflow discharge cavity 50312 through the transition connecting pipe 308, and is discharged to the external air transmission channel through a first air outlet communicated with the airflow discharge cavity 50312.

To avoid the situation that the metering module cannot work normally due to the fact that the rotor of the lumbar gear set 20 in the metering module is locked, a bypass opening for communicating the first diversion channel and the second diversion channel is formed in the side wall of the transition connection pipe 308, and a differential pressure switch 70 is disposed at the bypass opening.

When the rotor of the pinwheel set 20 is dead, after the gas flows into the gas flow buffer cavity 50311 from the first gas inlet, the pressure difference between the inside of the gas flow buffer cavity 50311 and the inside of the gas flow exhaust cavity 50312 increases, and when a certain threshold is reached, the pressure difference switch 70 operates to connect the gas flow buffer cavity 50311 and the gas flow exhaust cavity 50312, so that temporary gas supply can be realized for downstream users.

In one example, the pressure differential switch member 70 includes a fixed connection member provided on the transition connection pipe 308 and an elastic operation member provided on the fixed connection member and closing the bypass opening when in a free state.

The fixed connecting piece can be a component for fixing the elastic action piece, and the specific structural form is not limited.

The resilient action may comprise a component made of a resilient material. The elastic action piece can generate displacement under the action of a preset pressure difference.

The elastic action member can be implemented in various forms, and in order to make the flowmeter of the present embodiment simpler, in some examples, the elastic action member includes: the fixing connector comprises a baffle part and an elastic connecting part, wherein one end of the elastic connecting part is connected with the baffle part, and the other end of the elastic connecting part is connected with the fixing connector; the baffle part covers the bypass outlet formed on the transition connecting pipe 308, and the size of the baffle part is larger than the aperture size of the bypass outlet.

The baffle part can be made of any material which can not permeate fluid, the shape of the baffle part can be any shape, the thickness can be designed according to the pressure required to be borne in actual use, and the size of the baffle part is larger than the size of the aperture at the outlet of the bypass, so that the bypass is convenient to close.

The elastic connecting part can be made of elastic materials and can deform under the action of external force.

The embodiment of the application also provides a gas flowmeter measuring method, which is applied to a gas waist wheel flowmeter, wherein the gas waist wheel flowmeter comprises more than two metering cavities, each metering cavity is respectively provided with a waist wheel group, and the more than two waist wheel groups are arranged in parallel; the gas flow metering method comprises the following steps:

s100, enabling airflow to enter more than two metering cavities;

the set of lumbar wheels in each metering chamber may include a first rotor and a second rotor cooperating with the first rotor. When the three waist wheel sets are arranged in parallel, the plane of the rotation central shafts of the first rotor and the second rotor in one of the waist wheel sets and the plane of the rotation central shafts of the first rotor and the second rotor in the other waist wheel sets are not on the same plane.

And S102, performing rotation metering by more than two waist wheel sets.

And S104, discharging airflow by more than two metering cavities according to a certain time sequence peak staggering mode.

The two or more metering chambers may discharge the gas flows in a staggered peak manner according to a certain time sequence, which may mean that the time points of the gas flows with the maximum peak values discharged by the two or more metering chambers are different in the metering process, for example, the time point of the gas flow with the maximum peak value discharged by one metering chamber is delayed from the time point of the gas flow with the maximum peak value discharged by the other metering chamber.

In the embodiment of the application, the peak or trough of the gas flow of each metering cavity exhaust can be staggered according to the peak-off exhaust airflow of a certain time sequence, and thus, the pulsation of the gas flow of the meter exhaust can be gentle after the gas flow of each metering cavity is converged, and the pulsation phenomenon of the gas flow of the meter exhaust can be effectively reduced, so that the repeatability of the meter is good.

In order to ensure that the waist wheel sets in the measuring chambers have relatively stable relative positions during the measuring process, and further reduce the pulsation phenomenon of the gas flow discharged by the flow meter, in one example, the two or more waist wheel sets perform rotational measurement (step S102), which may include: the waist wheel groups in the at least two metering cavities rotate in a linkage manner to perform metering.

The waist wheel groups in the metering cavities rotate in a linkage manner, and the total gas discharge amount after the gas flow rates discharged by the metering cavities are superposed can be kept relatively stable in any time period.

In one example, each waist wheel set comprises a first rotor and a second rotor matched with the first rotor, and the first rotor or the second rotor of the waist wheel set in at least two metering cavities are connected through an inter-group linkage mechanism; wherein, the waist wheel group linkage in two at least measurement chambeies rotates, can include: and the first rotor or the second rotor of the waist wheel set in the at least two metering cavities is in linkage rotation through the inter-group linkage mechanism.

In one example, a first gear is connected to a first rotor of a waist wheel set in the at least two metering chambers, and a second gear is connected to a second rotor, wherein the second gear is meshed with the first gear;

wherein, the first rotor or the second rotor of the waist wheelset in at least two measurement chambeies pass through the linkage rotation of intergroup link gear, include: the first rotors of the waist wheel sets in the at least two metering cavities are in linkage rotation through the meshing of the first gear and a gear linkage mechanism or a synchronous belt;

the embodiment is not limited to this, and in other embodiments, the first rotor or the second rotor of the waist wheel set in the at least two metering chambers is linked to rotate through an inter-group linkage mechanism, and the method includes: and the second rotors of the waist wheel sets in the at least two metering cavities are in linkage rotation through the meshing of the second gear and a gear linkage mechanism or a synchronous belt.

As shown with reference to fig. 5. In one example, the two or more metering chambers are ejected peak to peak according to a certain time sequence (step S104), including: and the air flow metered by each metering cavity is exhausted through the respective exhaust port of each metering cavity, is converged into a common exhaust channel and is exhausted through the common exhaust channel.

Referring to fig. 16a and 16b, in another example, the two or more metering chambers are discharged according to a certain time sequence peak-to-peak discharge (step S104), and the method includes: the air flow metered by the first part metering cavity is exhausted through respective exhaust ports of the first part metering cavity, is converged into a first common exhaust channel and is exhausted through the first common exhaust channel; and the air flow metered by the second part metering cavity is exhausted through respective exhaust ports of the second part metering cavity, is converged into a second common exhaust passage and is exhausted through the second common exhaust passage.

Referring to fig. 17, in yet another example, the two or more metering chambers are ejected according to a timing offset (step S104), comprising: the air flow metered by the N-1 metering cavities is exhausted through respective exhaust ports of the N-1 metering cavities, is converged into a common exhaust channel and is exhausted through the common exhaust channel; and the air flow metered by the 1 metering cavity is discharged through an independent exhaust channel communicated with an exhaust port of the 1 metering cavity. Wherein N is the number of the metering cavities, and N is a natural number which is greater than 1 and less than or equal to 8.

In one example, each of the sets of pinions includes a first rotor and a second rotor cooperating with the first rotor; in each waist wheel set, along the clockwise or anticlockwise direction, in n first rotors from the first rotor of the 1 st waist wheel set to the first rotor of the nth waist wheel set, the included angle of the first rotor of the adjacent waist wheel set relative to the air inlet of the metering cavity in which the first rotor is located is increased in a preset angle gradient manner; the first rotor of each waist wheel set is one of the two rotors of each waist wheel set, and the rotor is positioned in the same installation position along the clockwise direction or the anticlockwise direction; the predetermined angular gradient is determined according to the following formula:

k＝90°/n±5°；

wherein k is a predetermined angular gradient;

n is the number of the waist wheel groups.

The gas flowmeter method of the embodiment can be applied to the gas roots flowmeter, and has the advantages basically the same as those of the gas roots flowmeter, and the description is omitted here.

It is noted that, herein, relational terms such as first and second, and the like may be used solely to distinguish one entity or action from another entity or action without necessarily requiring or implying any actual such relationship or order between such entities or actions. Also, the terms "comprises," "comprising," or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such process, method, article, or apparatus. Without further limitation, an element defined by the phrase "comprising an … …" does not exclude the presence of other identical elements in a process, method, article, or apparatus that comprises the element.

All the embodiments in the present specification are described in a related manner, and the same and similar parts among the embodiments may be referred to each other, and each embodiment focuses on the differences from the other embodiments.

The above description is only for the specific embodiments of the present application, but the scope of the present application is not limited thereto, and any changes or substitutions that can be easily conceived by those skilled in the art within the technical scope of the present application should be covered within the scope of the present application. Therefore, the protection scope of the present application shall be subject to the protection scope of the claims.

Claims (24)

1. A gas roots meter, comprising: more than two metering cavities, wherein each metering cavity is provided with a waist wheel set, and the more than two waist wheel sets are arranged in parallel;

more than two waist wheel sets are arranged in different relative metering positions in the metering cavities respectively.

2. The gas roots meter of claim 1, wherein the two or more metering chambers are located within the same chamber; and air inlets are respectively arranged at the positions corresponding to the metering cavities on the cavity body.

3. A gas roots meter according to claim 2, wherein a common exhaust channel is provided in the chamber in communication with the exhaust ports of at least two of the metering chambers, the common exhaust channel extending along the length of the chamber and being in communication with the exhaust port at one end of the chamber.

4. A gas waist wheel flow meter according to claim 2 wherein an inter-group linkage is provided between two or more waist wheel groups.

5. A gas waist wheel flow meter according to claim 4 wherein each waist wheel set comprises a first rotor and a second rotor cooperating with the first rotor, said inter-set linkage being coupled to the first or second rotor of more than two waist wheel sets.

6. The gas roots meter of claim 5, wherein the inter-group linkage is disposed outside the cavity and coupled to an end of the first rotor or the second rotor of more than two roots.

7. The gas roots meter of claim 6,

the first end of the first rotor of each waist wheel set is connected with a first gear, the first end of the second rotor of each waist wheel set is connected with a second gear, and the first gear and the second gear are the same in size and are meshed with each other;

the inter-group linkage mechanism is meshed with first gears connected with the first rotors of the more than two waist wheel sets, or meshed with second gears connected with the second rotors of the more than two waist wheel sets.

8. The gas roots meter of claim 7, wherein the inter-group linkage is a gear linkage or a timing belt.

9. The gas roots meter of claim 8,

the gear linkage mechanism comprises a group of inter-group linkage gears which are rotatably arranged outside the cavity and meshed with first gears connected with first rotors of more than two waist wheel groups or second gears connected with second rotors of more than two waist wheel groups;

alternatively, the first and second electrodes may be,

the gear linkage mechanism comprises a main linkage gear which is rotatably arranged outside the cavity, an intermediate gear is arranged between the main linkage gear and a first gear connected with first rotors of more than two waist wheel sets, and the intermediate gear is meshed with the main linkage gear and the first gear; or an intermediate gear is arranged between the main linkage gear and second gears connected with second rotors of more than two waist gear sets, and the intermediate gear is meshed with the main linkage gear and the second gears;

alternatively, the first and second electrodes may be,

the gear linkage mechanism comprises a gear ring which is arranged outside the cavity and is meshed with first gears connected with first rotors of more than two waist wheel sets or meshed with second gears connected with second rotors of more than two waist wheel sets.

10. A gas waist wheel flow meter according to claim 1 or 2, wherein each waist wheel set comprises a first rotor and a second rotor cooperating with the first rotor;

in each waist wheel set, along the clockwise or anticlockwise direction, in n first rotors from the first rotor of the 1 st waist wheel set to the first rotor of the nth waist wheel set, the included angle of the first rotor of the adjacent waist wheel set relative to the air inlet of the metering cavity in which the first rotor is located is increased in a preset angle gradient manner; the first rotor of each waist wheel set is one of the two rotors of each waist wheel set, and the rotor is positioned in the same installation position along the clockwise direction or the anticlockwise direction;

the predetermined angular gradient is determined according to the following formula:

k＝90°/n±5°；

wherein k is a predetermined angular gradient;

n is the number of the waist wheel groups.

11. The gas roots meter of claim 1, wherein the two or more metering chambers are two, three, or four metering chambers.

12. The gas roots meter of claim 2, wherein the partition wall between two adjacent metering chambers is of a symmetrical configuration with respect to a center plane of symmetry between the two adjacent metering chambers; the symmetry center plane passes through the central axis of the cavity;

alternatively, the first and second electrodes may be,

the partition wall between two adjacent metering cavities is in an asymmetric structure relative to a symmetric center plane between the two adjacent metering cavities, and the symmetric center plane passes through the central axis of the cavity.

13. The gas roots meter of claim 2, further comprising a housing, the metering module being removably disposed within the housing; the metering module comprises a cavity body with a metering cavity inside and a waist wheel set in each metering cavity;

the shell is provided with a first air inlet and a first air outlet which are communicated with an external air flow conveying pipeline;

the shell is internally provided with a first flow guide channel communicated with the first air inlet and the air inlets of the metering cavities, and a second flow guide channel communicated with the air outlet of the cavity and the first air outlet.

14. The gas roots meter of claim 13, wherein the housing comprises a housing body having an opening for accessing the metering module, the opening being covered by a cover; the metering module is arranged in the shell body; the first air inlet and the first air outlet are arranged on the shell body.

15. The gas roots meter of claim 14, wherein the housing body comprises a pipe connection portion and a metering module receiving portion;

an airflow buffer cavity and an airflow discharge cavity are arranged in the pipeline connecting part, and the airflow buffer cavity is isolated from the airflow discharge cavity; the first air inlet and the first air outlet are arranged on the pipeline connecting part; the airflow buffer cavity is respectively communicated with the first air inlet and the air inlets of the metering cavities, and the airflow discharge cavity is respectively communicated with the air outlet of the cavity and the first air outlet;

the measurement module holds and has the measurement module in the portion and hold the chamber, the measurement module is established the measurement module holds in the chamber.

16. The gas roots meter of claim 15, wherein the gas flow discharge chamber is a cylindrical structure extending along the central axis of the housing, and the gas flow buffer chamber is an incomplete annular structure surrounding the gas flow discharge chamber.

17. The gas roots meter of claim 15, wherein the gas inlet of each metering chamber is disposed on a side wall of the chamber body, and a predetermined gap is provided between the inlet of the gas inlet of each metering chamber and the inner wall of the metering module receiving chamber; the airflow buffer cavity is communicated with the preset gap, and the airflow buffer cavity and the metering module accommodating cavity form the first flow guide channel.

18. The gas roots meter of claim 15, wherein a transition connection pipe is connected to the gas outlet of the chamber, the transition connection pipe extends from the gas outlet of the chamber into the gas flow discharge chamber, and the transition connection pipe and the gas flow discharge chamber form the second diversion channel.

19. A gas roots meter according to claim 15, wherein a fluid filter is provided within the housing between the outlet of the flow buffer chamber and the inlet of each metering chamber.

20. The gas roots meter of claim 19, wherein the metering module receiving chamber is in communication with the gas flow buffer chamber and the gas flow exhaust chamber, respectively;

the metering module accommodating cavity is communicated with the airflow buffer cavity and is provided with a step, the fluid filter member is supported on the step, and the metering module is supported on the fluid filter member.

21. The gas roots meter of claim 20, wherein the fluid filter element comprises an annular support frame, wherein filter holes are formed in a side wall of the support frame, and a filter screen is arranged on the support frame at a position corresponding to the filter holes; wherein the bracket is supported on the step.

22. The gas roots meter of claim 18, wherein a bypass opening is provided in a sidewall of the transition connection tube to communicate the first and second flow channels, and a differential pressure switch is provided at the bypass opening.

23. The gas roots meter of claim 22, wherein the differential pressure switch member comprises a fixed connection member provided on the transition connection tube and an elastic action member provided on the fixed connection member and closing the bypass opening when in a free state.

24. A gas waist wheel flow meter according to claim 1 wherein an inter-group linkage is provided between two or more waist wheel groups.

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