CN1057835C

CN1057835C - Rotor positive-displacement flow-meter

Info

Publication number: CN1057835C
Application number: CN 95103885
Authority: CN
Inventors: 赵汝沅
Original assignee: Individual
Current assignee: Individual
Priority date: 1995-04-25
Filing date: 1995-04-25
Publication date: 2000-10-25
Anticipated expiration: 2015-04-25
Also published as: CN1134545A

Abstract

The present invention discloses a rotor volume flowmeter used for pushing the rotation of a volume chamber generated from the design among a rotor, a casing and a core column, and quantitatively transmitting fluid from an inlet to an outlet to complete the metering of fluid through the push of the differential pressure of fluid. Because a cylindrical surface or a plane surface is selected to form the connecting part between a moving piece and a static piece, which can most easily improve processing and assembly precision, the gliding flow in the metering process is reduced, the measuring accuracy is enhanced, and the production is easy to carry out. The proposal of a single volume chamber and a plurality of volume chambers has the advantages of improving dynamic unbalance in a rotation metering, reducing noise and abrasion and forming serial products.

Description

A kind of rotor displacement flowmeter

The present invention relates to a kind of by volumeter by meter fluid institute driven plunger rotor.

The patent No. that was disclosed in 1976 is 3969940 United States Patent (USP), discloses a kind of rotator type volumeter (seeing Fig. 1 and Fig. 2).It is by shell (41), lid (40), two rotating shafts (112) and (111), two transmission gears (56) that drive rotation axis and (55), four top (117), two locating pieces (115) and the end face vane type metering rotor a (119) and the vane type metering rotor b (100) of rotation form by two axles drives respectively, there are two central axis be parallel to each other cylindrical cavity a and cylindrical cavity b in the centre of its shell, and the cross section radius of a circle of this two cylindrical cavity equates that the distance of two cylindrical cavity central axis is less than the diameter of this cylindrical cavity.Its blade rotor is made up of body (101) and blade (102) (see figure 2), by blade flowmeter import and outlet is cut off, and forms measuring chamber.Rotor body plays a part support blade and keeps relative position between blade, its essence is an end face blade flowmeter.Known volumetric flow is in respect of polytype, their common feature is: between the measuring sensor of motion and the relative static element, form the fixing measuring chamber of volume, push the fluid in the measuring chamber to outlet from the flowmeter import, thereby finish the metering of the volume of convection cell by measuring sensor; Because the difference of machining precision, assembly precision, in order to make relative motion become possibility, between movement parts and the static element certain clearance need be arranged, because exist pressure reduction between flowmeter import and the outlet, gap and pressure reduction make segment fluid flow miss to outlet from import through the gap without metering, and this Fluid Volume of missing is called " slip-stream amount ".What and stability thereof of slip-stream amount for the accuracy of measuring of volumeter, are vital.So the size of strict control gap, the length of increase leakage channel then becomes the essential condition that improves the volumeter accuracy of measuring.Identical with the characteristics of all blade flowmeter, its leakage channel length along the circumferential direction only is the thickness of blade.From the angle of processing,, directly influence the raising of the flowmeter accuracy of measuring because the end face of blade and rotor body joining place is difficult to carry out Precision Machining.

The objective of the invention is to: the technical scheme that a kind of piston rotary volumeter is provided, have in mind from being easy to precision machined body, each parts of redesign flowmeter, make the as far as possible little gap of maintenance between moving component and the stationary parts, make them that big as far as possible relative motion interface be arranged, long as far as possible leakage channel is arranged, thereby reduce the accuracy that the slip-stream amount improves metering as far as possible.

In order to reach the above object better, we have proposed the design proposal (see figure 3) as Fig. 3, the stationary parts that flowmeter of the present invention participates in metering is made of housing (7), end cap (4) and stem stem (5), there are two diameters and highly identical the centre of its housing (7), parallel axes, cylindrical cavity a and cylindrical cavity b that circumference intersects, distance between the axis of two cavitys is less than a cavity inside radius and a stem stem (5) external radius sum, greater than a cavity radius and a stem stem (5) inside radius sum; Between the installation base surface of its cavity axis and flowmeter can be vertical, can be parallel, also can select other relative positions; The distance of two cavity axis is d with the difference of cavity inside radius and stem stem (5) external radius sum, have import (13) and outlet (14) (see figure 4) of the fluid that is measured in the intersection of two cylindrical cavity cylinders, the moving component that the present invention participates in measuring is the positive displacement rotor.It is two identical piston rotaries (6a) and (6b) in the design, each piston rotary all is by corresponding piston body (9a) and (9b) and piston seat (8a) and (8b) constitute, the xsect of piston body (9a), (9b) is arc, be with a static stem stem (5a) and (5b) in its piston respectively, stem stem (5) is a hollow right cylinder, on the external cylindrical surface of stem stem, have cylinder groove (20) (see figure 5) of a depression, the cross section thickness of cylinder groove (20) is the d (see figure 6).The radius-of-curvature of the cylinder groove (20) of depression is identical with housing cylinder inner chamber radius, and the center of curvature of the cylinder groove (20) of depression is the axis of another cylinder cavity of housing.Rotation axis (3a) and rotation axis identical with it (3b) are housed respectively in stem stem, bearing (10) and securing member (11) are housed respectively at two of rotation axis, the one end is equipped with identical gear a (2a) and gear b (2b) again respectively, magnetic coupler (1) also is housed respectively on two rotation axiss, is used for to counting assembly output and transmits the signal of the angular displacement of piston rotary and transmission shaft; The feature of its rotating piston is: nominally the distance of two-piston rotating shaft equals a cavity inside radius R poor with stem stem external radius sum and cylinder slot thickness d.Its housing (7), end cap (4), stem stem (5), piston rotary (6) satisfy following relation: two inner chamber internal diameter basic sizes of two-piston body (9a) and external diameter (9b) and shell (7) equate; Two-piston body (9a) and internal diameter (9b) and two stem stems (5a) and external diameter basic size (5b) equate; The height of two-piston body (9a) and height (9b) and housing (7) two inner chambers and two stem stems (5a) and working depth basic size (5b) equate; Being intended that of present design, select the body of the easiest raising machining precision parts, guarantee the raising of machining precision and assembly precision, thereby reduce the gap between movement parts and the static element as far as possible, reduce the slip-stream amount that produces owing to the gap, improve the accuracy of flowmeter metering.For the precision that guarantees to process and assemble, in the design, all moving components and and the position of the stationary parts that connects with it of moving component, the face of cylinder or plane have all been selected for use, and form the piston body (9a) (96) of piston rotary and piston seat (8a) (8b), can be that one processes, also can be after processing respectively, to be fixed together by designing requirement again.In the timing of flowmeter integral installation, two rotors can unanimity all forward (being that a and b rotor are all along a direction), perhaps select reverse (being that a and b rotor are satisfying under the condition of parallel axes) separately towards a direction.Piston body (9) and the piston seat (8) of forming piston rotary (6), we can do a plane by the axis of piston rotary, make piston body in this both sides, plane institute counterpart symmetry, and we claim that this plane is the piston body plane of symmetry, as the Y plane among Fig. 7.

For improving the dynamically balanced performance of this flowmeter, the piston body (9) of piston rotary of the present invention (6) can also be designed to many pistons build, be two-piston rotor (6a) and (6b) on piston body can be one, can be identical two, also can be identical three.

When being single piston body structure, a piston rotary (sees Fig. 3 and Fig. 5), the central angle that its each piston body had is less than 180 °, its two-piston rotor (6) need satisfy the ad-hoc location assembling when assembling, promptly install the back in rotation, need to guarantee have a state to be:, when the plane of symmetry of the plane of symmetry of piston body a and piston body b overlaps, its corresponding piston body (9) is the arc back of a bow towards a direction (as the figure of the A among Fig. 9);

(see figure 10) when a piston rotary is two piston body structures, the central angle that its each piston body had is less than 90 °, two piston bodies on same piston rotary need be installed in the both sides of central axis, opposite face and adorning, and the plane of symmetry of two-piston body overlaps; (promptly two planes of symmetry become 180 °) its two-piston rotor (6) time need satisfy the ad-hoc location assembling in assembling, promptly installs the back in rotation, needs to guarantee have a state to be, the plane of symmetry of piston body a needs and the plane of symmetry perpendicular (seeing Figure 15) of piston body b;

When a piston rotary is three piston body structures (seeing Figure 14), the central angle that its each piston body had is less than 60 °, three piston bodies on same piston rotary need isogonism that (promptly the plane of symmetry of three piston bodies becomes 120 °) is installed, its two-piston rotor (6) need satisfy the ad-hoc location assembling when assembling, promptly install the back in rotation, need guaranteeing have a state to be: during position, space in the middle of the piston body of piston body a forwards two piston bodies of piston body b to, the plane of symmetry of two piston bodies in addition of its piston body a, the plane of symmetry of the 3rd piston body of need and piston body b overlaps (seeing Figure 16); In order to reduce unbalance dynamic, piston body also can cause hollow (seeing Figure 17).Along two stem stems (5a) and external cylindrical surface (5b), respectively have the cylinder groove (20) of a depression, the radius-of-curvature of cylinder groove (20) is identical with housing cylinder inner chamber radius, its center of curvature is the axis of another cylinder cavity of housing, when assembling, the plane of symmetry of two stem stems need overlap, and the distance of two cylinder grooves (20) the shortest (see Fig. 6, the Z-Z plane is exactly the plane of symmetry of stem stem among the figure).Because stem stem is static, during fabrication, stem stem (5a) and (5b) can all be fixed on the end cap (4) can all be fixed on the housing (7), also can be separately fixed on end cap (4) and the housing (7).Import of its fluid that is measured (13) and outlet (14) can be arranged on the intersection on the two cavity faces of cylinder of housing (7) respectively symmetrically, also can be arranged on (see figure 4) on the pairing end face of intersection.

Fig. 9 has provided the schematic diagram of single piston body flowmeter metered flow, in Fig. 9, the housing (7), end cap (4), piston rotary a, piston rotary b, stem stem a, stem stem b, piston body a, piston body b of sealing is divided into fluid input cavity (17a) and (17b) to the space in the housing, (the fluid input cavity (17b) of this moment has in fact become the measuring chamber that the design's volume is fixed) and fluid output cavity (18a) and (18b).Fluid keeps a pressure differential between import (13) and outlet (14), along with the promotion of hydrodynamic pressure and the engagement of transmitting gear, fluid can only advance from import, exports out.In rotation, fluid input cavity (17a) and (17b) and fluid output cavity (18a) and volume (18b) constantly changing.We can clearly explain the process that clear the present invention measures and the principle of metering from Fig. 9.From the A of Fig. 9 figure, formed fluid input cavity (17b) between piston body (9b) housing (7) and stem stem (5b), fluid input cavity (17b) pressure flowing full body at this moment, the volume maximum, and the path of cavity and import, outlet is cut off; Between housing (7), piston body (9a), stem stem (5a) and piston body (9b), under the promotion of import (13) hydrodynamic pressure, from childhood and the earth has formed fluid input cavity (17a); Between housing (7), piston body (9a), stem stem (5a) and piston body (9b) formed liquid output cavity (18a) and outlet (14) connect, the fluid output cavity is under the promotion of hydrodynamic pressure, volume is more and more littler, the fluid of depositing in it is extruded from cavity, and row is to outlet (14).The volume of fluid input cavity (17a) continues to enlarge when rotor forwards the B figure position of Fig. 9 to, and fluid continues to enter, until becoming the fixing measuring chamber of volume.In the b rotor, because the outlet of having opened fluid in rotation, (17b) of the former input cavity of fluid before this become fluid output cavity (18b) suddenly, and fluid is extruded from the chamber.The volume maximum of fluid input cavity (17a) when rotor forwards the C figure position of Fig. 9 to, the volume of fluid output cavity (18b) continues to reduce, fluid input cavity (17b) begins to be pressed into fluid, fluid input cavity this moment (17a) is in the state volume maximum of measuring chamber, and the path of cavity and import, outlet has been cut off the formation measuring chamber.The volume of fluid input cavity (17b) continues to enlarge when rotor forwards the D figure position of Fig. 9 to, fluid continues to be pressed into, in a rotor, because the outlet of in rotation, having opened fluid, the state that (17a) of the former input cavity of fluid before this is in measuring chamber has become fluid output cavity (18a) suddenly, and fluid is extruded from the chamber.Finished the moving process that rotates a circle to this rotor, each rotor has been finished the process that liquid enters and discharges.Owing to enter is that the fluid depended on pressure of controlling oneself is compressed into, being again to carry out under the tight seal state, and discharge being that rotor part in the motion is extruded, also is to carry out under the tight seal state, accurate processing component has guaranteed the wastage of MIN fluid, reaches the effect of delicate metering.Piston body in the cavity of housing of the present invention can be one, also can be equal-sized two or symmetry equal-sized three of symmetry.Two gears (2a) are the identical and intermeshed gear of structure with (2b), and two rotating pistons are from original relative position, and under the effect of two gears that are meshing with each other, it is opposite to make direction, the rotation that angular displacement is synchronous.Because the pressure at fluid inlet place is higher than the pressure of exit fluid, the pressure reduction of fluid between the import and export is unique power that driven plunger is rotated, and rotation axis is exported the signal of its angular displacement to external world, the fluid volumes amount that was measured in order to representative.The accuracy of volumeter of the present invention design can be divided into two classes, and the first kind, the fundamental error of flowmeter be not more than ± and 0.1%, repetitive error is not more than 0.05%.This flowmeter can be used as proving flowmeter and uses, and is used to examine and determine error in dipping at other flowmeters of ± 0.5%～± 0.3%.Second class, the fundamental error of flowmeter be not more than ± and 0.2%, repetitive error is not more than 0.1%, can be used as work measuring instrument and uses.For the dependable flow meter reaches the above-mentioned accuracy of measuring, flow of the present invention is in respect of following restrictive condition:

1. the latus rectum of flowmeter is Φ 25～Φ 200mm;

2. the viscosity of fluid of being measured is not less than 0.001Pa S;

3. the ratio of maximum flow and minimum flow is not less than 5;

4. use the external delivery rate signal of electric pulse sensing device, be in lower bound at viscosity, under the maximum flow condition, the flowmeter inlet outlet pressure differential is not more than 20KPa.

Design proposal of the present invention, the measurement component of its measuring chamber and stationary parts all are to be made of the face of cylinder and plane, do not have any special surface.In machining, face of cylinder peace face easily realizes high-precision processing, in assembling, realize that easily high-precision assembling and the design have considered between measurement component and the stationary parts, the identical cylinder of plane and plane, nominal curvature and cylinder are all to cover mutually than large tracts of land and to be connected; The slit of the surface of contact that forms between the import of flowmeter and outlet is very long, and promptly leakage channel is longer.Therefore the slip-stream amount is limited in a very low level, thereby improved the accuracy of measuring of flowmeter, again because as the center of rotation of the piston rotary of measurement component, be to determine its axial location by the bearing on the rotation axis, fixing gap is arranged between piston rotary and the stationary parts, the tolerance of its machining precision guarantees that promptly moving component and stationary parts do not contact with each other, and guarantees again not produce or few produce " slip-stream amount " within accuracy.As get rid of outside the factor of fluid, should there be direct friction between the two, so flowmeter should have long serviceable life.Flowmeter in the course of the work, there are not the to-and-fro movement of any macroscopic view in parts and fluid, so be not subjected to the restriction of reciprocal inertia force, can adopt big circulation area, are used for the metering of big flow.If the pressure reduction of import (13) and outlet (14) is excessive, big to can make housing distortion the time, the size of this flowmeter stationary parts can change (increasings) so, and " slip-stream amount " can increasing in metering process, causes the decline of the flowmeter accuracy of measuring.In this case, this flowmeter can be taked double-layer shell structure, internal layer is this flowmeter, wrap a housing again in the outside of flowmeter, the fluid skin of coming in to be full of earlier, and then enter flowmeter from import (13), thus reduced the inside and outside pressure reduction of flowmeter shell itself, make housing not produce deformation or few generation distortion, in the accuracy of dependable flow metering.As for the expansion of outer casing, irrelevant with the accuracy of metering.

The present invention has following accompanying drawing;

Fig. 1 is the synoptic diagram of United States Patent (USP) 3969940 flowmeters;

Each icon is explained as follows: shell (40), moving gear b (55), moving gear a (56), blade rotor b (100), blade rotor a (119), apical axis (117), rotating shaft a (111) rotating shaft b (112), locating piece (115).

Fig. 2 is the blade rotor synoptic diagram of United States Patent (USP) 3969940 flowmeters;

Each icon is explained as follows: rotor body (101), blade (102).

Fig. 3 is the positive cross-sectional schematic that the flowmeter first embodiment piston rotary of the present invention forward assembles:

Each mark is separated as follows among the figure: magnetic coupler (1), gear (2), rotation axis (3), end cap (4), stem stem (5), piston rotary (6), housing (7).

Fig. 4 is the front surface A-A cross-sectional schematic of first embodiment of the invention;

Each icon is explained as follows among the figure: import (13), outlet (14).

Fig. 5 is the critical piece synoptic diagram of a piston rotary of first embodiment of the invention;

Each mark is separated as follows among the figure: piston seat (8), piston body (9), bearing (10).

Fig. 6 is a housing stem stem rigging position synoptic diagram of the present invention;

Fig. 7-the 1st, first embodiment of the invention piston rotary schematic top plan view;

Each icon is explained as follows among the figure: piston body (9), piston seat (8), outer camber line (15), interior camber line (16).

Fig. 7-the 2nd, the I-I cross-sectional schematic of Fig. 7-1.

Fig. 8 is the first embodiment of the present invention, the positive cross-sectional schematic of the flowmeter of the reverse assembling of single piston body piston rotary.

Fig. 9 is a first embodiment of the invention principle of work synoptic diagram;

Each icon is explained as follows among the figure: influent stream body cavity (17), go out fluid cavity (18).

Figure 10-the 1st, the dual-active cock body piston rotary schematic top plan view of second embodiment of the invention.

Figure 10-the 2nd, the II-II cross-sectional schematic of Figure 10-1.

Figure 11 is the positive cross-sectional schematic of flowmeter that the dual-active cock body piston rotary of second embodiment of the invention forward assembles.

Figure 12 is flowmeter front surface A-A cross-sectional schematic that the dual-active cock body piston rotary of second embodiment of the invention forward assembles.

Figure 13 is the positive cross-sectional schematic of flowmeter of the reverse assembling of dual-active cock body piston rotary of second embodiment of the invention.

Figure 14-the 1st, three piston body piston rotary schematic top plan view of third embodiment of the invention.

Figure 14-the 2nd, the III-III cross-sectional schematic of Figure 14-1.

Figure 15 is the rigging position synoptic diagram of dual-active cock body on flowmeter.

Figure 16 is the rigging position synoptic diagram of three piston bodies on flowmeter.

Figure 17-the 1st, first embodiment of the invention hollow piston body piston rotary schematic top plan view;

Each icon is explained as follows among the figure: hollow piston body (19).

Figure 17-the 2nd, the A-A cross-sectional schematic of Figure 17-1.

The present invention has following examples:

Fig. 3 is the first embodiment of the present invention, and it is the flowmeter of single piston body structure in the piston rotary, and its technical scheme has been done the narration of detailed complete in front.

Second embodiment that Figure 10 is given, be the design proposal that two piston bodies are arranged in each piston rotary, the stationary parts structure of this scheme is still by shell (7), end cap (4) and stem stem (5) constitute, on housing (7) still design have fluid import (13) and, export (14); The moving component of participating in gage work remains piston rotary (6), piston rotary is made up of piston body (9) and piston seat (8), be with static stem stem (5) in the piston rotary, rotation axis (3) is housed in the stem stem, bearing (10) and packing ring (11) are equipped with in axle two, and an end of axle is equipped with gear (2) and magnetic coupler (1).Different with first embodiment is: (see figure 10) when a piston rotary is two piston body structures, the central angle that its each piston body had is less than 90 °, two piston bodies on same piston rotary need be installed in the both sides of central axis, opposite face and adorning, and the plane of symmetry of two-piston body overlaps; Its two-piston rotor (6) time need satisfy the symmetry assembling in assembling, promptly installs the back in rotation, and the plane of symmetry of piston body a needs and the symmetry of piston body b practise physiognomy vertical (seeing Figure 15).

The 3rd embodiment that Figure 11 is given, be the design proposal that three piston bodies are arranged in each piston rotary, the stationary parts structure of this scheme is still by shell (7), end cap (4) and stem stem (5) constitute, on housing (7) still design have fluid import (13) and, export (14); The moving component of participating in gage work remains piston rotary (6), piston rotary is made up of piston body (9) and piston seat (8), be with static stem stem (5) in the piston rotary, rotation axis (3) is housed in the stem stem, bearing (10) and packing ring (11) are equipped with in axle two, and an end of axle is equipped with gear (2) and magnetic shaft joint (1).Different with the one the second embodiment is: when a piston rotary is three piston body structures (seeing Figure 14), the central angle that its each piston body had is less than 60 °, three piston bodies on same piston rotary need isogonism to install, its two-piston rotor (6) need satisfy the symmetry assembling when assembling, promptly install the back in rotation, need guaranteeing have a state to be: during position, space in the middle of the piston body of piston body a forwards two piston bodies of piston body b to, the plane of symmetry of two piston bodies in addition of its piston body a, the plane of symmetry of the 3rd piston body of need and piston body b overlaps (seeing Figure 16).

Claims

1. rotor displacement flowmeter, it by the shell of cylindrical cavity in being parallel to by two, lid, two rotating shafts, two drive a gear and the volumetric metering rotors that axle rotates and form, it is characterized in that:

1). the stationary parts of flowmeter is made of housing (7), end cap (4) and stem stem (5), cylindrical cavity a and cylindrical cavity b that the centre of its housing has two axis to be parallel to each other, distance between the central axis of two cavitys is less than a cavity inside radius and a stem stem (5) external radius sum, greater than a cavity radius and a stem stem (5) inside radius sum; Between the installation base surface of its cavity axis and flowmeter can be vertical, can be parallel, also can select other directions; The distance of two cavity axis is d with the difference of cavity inside radius and stem stem (5) external radius sum;

2). four rolling bearings (10) are arranged;

3). its housing (7), end cap (4), stem stem (5), piston rotary (6) satisfy following relation: two-piston body (9a) and external diameter (9b) and shell (7) two cavity internal diameter basic sizes equate; Two-piston body (9a) and internal diameter (9b) and two stem stems (5a) and external diameter basic size (5b) equate; The height of two-piston body (9a) and height (9b) and housing (7) inner chamber and two stem stems (5a) and working depth basic size (5b) equate;

4). its positive displacement rotor is the equal-sized piston rotary (6a) and the piston rotary identical with it (6b) of two symmetries, it is by identical piston body (9a) and (9b) and piston seat (8a) and (8b) constitute, be with a static identical stem stem (5a) and (5b) in its piston body respectively, stem stem (5) is a hollow right cylinder, rotation axis (3a) and rotation axis identical with it (3b) are housed respectively in stem stem, bearing (10) and securing member (11) are housed at two of rotation axis, the one end is equipped with identical gear (2a) and gear (2b) again respectively, and magnetic coupler (1) is housed;

5). its two-piston rotor (6a) and (6b) in piston body (9) can be one, can be identical two, also can be identical three;

6). the number difference of piston rotary inner carrier body, the structure of its piston body is also inequality,

1., when a piston rotary is single piston body structure, the central angle that its each piston body had is less than 180 °, its two-piston rotor (6) need satisfy the ad-hoc location assembling when assembling, promptly install the back in rotation, need guaranteeing have a state to be: when the plane of symmetry of the plane of symmetry of piston body a and piston body b overlapped, its corresponding piston body (9) was the arc back of a bow towards a direction;

2., when a piston rotary is two piston body structures, the central angle that its each piston body had is less than 90 °, two piston bodies on same piston rotary need be installed in the both sides of central axis, opposite face and adorning, and the plane of symmetry of two-piston body overlaps, its two-piston rotor (6) need satisfy the ad-hoc location assembling when assembling, promptly install the back in rotation, and need to guarantee have a state to be: the plane of symmetry of piston body a needs to practise physiognomy vertical with the symmetry of piston body b;

3., when a piston rotary is three piston body structures, the central angle that its each piston body had is less than 60 °, three piston bodies on same piston rotary need isogonism to install, its two-piston rotor (6) need satisfy the ad-hoc location assembling when assembling, promptly install the back in rotation, need guaranteeing have a state to be: when the piston body of piston body a forwards the position, space of two piston bodies of piston body b to, the plane of symmetry of another piston body of piston body a, the plane of symmetry of the 3rd piston body of need and piston body b overlaps;

7). along two stem stems (5a) and external cylindrical surface (5b), respectively have the cylinder groove (20) of a depression, the radius-of-curvature of cylinder groove (20) is identical with housing cylinder inner chamber radius, its center of curvature is the axis of another cylinder cavity of housing, the cylinder groove (20) of its depression nominally the square section along the square between two camber lines from equaling d, when assembling, the plane of symmetry of two-piston rotor inner leg need overlap, and the distance of two cylinder grooves (20) is the shortest.

2. flowmeter according to claim 1 is characterized in that: piston body (9a) and (9b) can be solid also can be hollow.

3. flowmeter according to claim 1, it is characterized in that: form respectively piston rotary (6a) and piston body (6b) (9a) (9b) and piston seat (8a) (8b), can be that one processes, also can be after processing respectively, to be fixed together by designing requirement again.

4. flowmeter according to claim 1 is characterized in that: stem stem (5a) and (5b) can all be fixed on the end cap (4), can all be fixed on the housing (7), and also can be separately fixed on end cap (4) and the housing (7).

5. flowmeter according to claim 1 is characterized in that: import of the fluid that is measured (13) and outlet (14) can be arranged on the intersection of two cylindrical cavities of housing (7) respectively symmetrically, also can be arranged on the pairing end face of intersection.