CN110821835A  Conical screw rotor of doublescrew vacuum pump  Google Patents
Conical screw rotor of doublescrew vacuum pump Download PDFInfo
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 CN110821835A CN110821835A CN201911347029.6A CN201911347029A CN110821835A CN 110821835 A CN110821835 A CN 110821835A CN 201911347029 A CN201911347029 A CN 201911347029A CN 110821835 A CN110821835 A CN 110821835A
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 screw rotor
 spherical
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 conical screw
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 210000004746 Tooth Root Anatomy 0.000 claims abstract description 20
 230000005540 biological transmission Effects 0.000 claims abstract description 10
 210000002320 Radius Anatomy 0.000 claims description 70
 239000000126 substance Substances 0.000 claims description 11
 229910000831 Steel Inorganic materials 0.000 claims description 3
 239000010959 steel Substances 0.000 claims description 3
 230000001360 synchronised Effects 0.000 claims description 2
 230000003247 decreasing Effects 0.000 claims 1
 238000007906 compression Methods 0.000 abstract description 6
 230000002349 favourable Effects 0.000 abstract description 2
 238000005086 pumping Methods 0.000 abstract description 2
 239000011295 pitch Substances 0.000 description 35
 238000010586 diagram Methods 0.000 description 4
 230000000694 effects Effects 0.000 description 4
 238000000034 method Methods 0.000 description 3
 238000007789 sealing Methods 0.000 description 2
 238000006073 displacement reaction Methods 0.000 description 1
 230000004048 modification Effects 0.000 description 1
 238000006011 modification reaction Methods 0.000 description 1
 230000000737 periodic Effects 0.000 description 1
Classifications

 F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
 F04—POSITIVE  DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS FOR LIQUIDS OR ELASTIC FLUIDS
 F04C—ROTARYPISTON, OR OSCILLATINGPISTON, POSITIVEDISPLACEMENT MACHINES FOR LIQUIDS; ROTARYPISTON, OR OSCILLATINGPISTON, POSITIVEDISPLACEMENT PUMPS
 F04C25/00—Adaptations of pumps for special use of pumps for elastic fluids
 F04C25/02—Adaptations of pumps for special use of pumps for elastic fluids for producing high vacuum

 F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
 F04—POSITIVE  DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS FOR LIQUIDS OR ELASTIC FLUIDS
 F04C—ROTARYPISTON, OR OSCILLATINGPISTON, POSITIVEDISPLACEMENT MACHINES FOR LIQUIDS; ROTARYPISTON, OR OSCILLATINGPISTON, POSITIVEDISPLACEMENT PUMPS
 F04C18/00—Rotarypiston pumps specially adapted for elastic fluids
 F04C18/08—Rotarypiston pumps specially adapted for elastic fluids of intermeshingengagement type, i.e. with engagement of cooperating members similar to that of toothed gearing
 F04C18/12—Rotarypiston pumps specially adapted for elastic fluids of intermeshingengagement type, i.e. with engagement of cooperating members similar to that of toothed gearing of other than internalaxis type
 F04C18/14—Rotarypiston pumps specially adapted for elastic fluids of intermeshingengagement type, i.e. with engagement of cooperating members similar to that of toothed gearing of other than internalaxis type with toothed rotary pistons
 F04C18/16—Rotarypiston pumps specially adapted for elastic fluids of intermeshingengagement type, i.e. with engagement of cooperating members similar to that of toothed gearing of other than internalaxis type with toothed rotary pistons with helical teeth, e.g. chevronshaped, screw type

 F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
 F04—POSITIVE  DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS FOR LIQUIDS OR ELASTIC FLUIDS
 F04C—ROTARYPISTON, OR OSCILLATINGPISTON, POSITIVEDISPLACEMENT MACHINES FOR LIQUIDS; ROTARYPISTON, OR OSCILLATINGPISTON, POSITIVEDISPLACEMENT PUMPS
 F04C18/00—Rotarypiston pumps specially adapted for elastic fluids
 F04C18/48—Rotarypiston pumps with nonparallel axes of movement of cooperating members
 F04C18/54—Rotarypiston pumps with nonparallel axes of movement of cooperating members the axes being arranged otherwise than at an angle of 90 degrees
 F04C18/56—Rotarypiston pumps with nonparallel axes of movement of cooperating members the axes being arranged otherwise than at an angle of 90 degrees of intermeshing engagement type, i.e. with engagement of cooperating members similar to that of toothed gearing
 F04C18/565—Rotarypiston pumps with nonparallel axes of movement of cooperating members the axes being arranged otherwise than at an angle of 90 degrees of intermeshing engagement type, i.e. with engagement of cooperating members similar to that of toothed gearing the axes of cooperating members being on the same plane

 F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
 F04—POSITIVE  DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS FOR LIQUIDS OR ELASTIC FLUIDS
 F04C—ROTARYPISTON, OR OSCILLATINGPISTON, POSITIVEDISPLACEMENT MACHINES FOR LIQUIDS; ROTARYPISTON, OR OSCILLATINGPISTON, POSITIVEDISPLACEMENT PUMPS
 F04C29/00—Component parts, details or accessories of pumps or pumping installations, not provided for in groups F04C18/00  F04C28/00

 F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
 F04—POSITIVE  DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS FOR LIQUIDS OR ELASTIC FLUIDS
 F04C—ROTARYPISTON, OR OSCILLATINGPISTON, POSITIVEDISPLACEMENT MACHINES FOR LIQUIDS; ROTARYPISTON, OR OSCILLATINGPISTON, POSITIVEDISPLACEMENT PUMPS
 F04C2240/00—Components
 F04C2240/20—Rotors
Abstract
The invention discloses a conical screw rotor of a doublescrew vacuum pump, wherein a left conical screw rotor (1) of the conical screw rotor is composed of a highpressure end concave spherical surface, a lowpressure end convex spherical surface and 4 tooth surfaces: the tooth surface comprises a left conical tooth crest (11), a left conical oblique tooth surface (12), a left conical tooth root surface (13) and a left conical concave tooth surface (14); the right conical screw rotor (2) consists of a highpressure end concave spherical surface, a lowpressure end convex spherical surface and 4 tooth surfaces: a right conical tooth crest (21), a right conical oblique tooth flank (22), a right conical tooth root surface (23) and a right conical concave tooth flank (24). The left conical screw rotor (1) and the right conical screw rotor (2) can realize the meshing of crossed shafts with the transmission ratio of 1 to 1, have larger air suction volume under the same structural parameters, have larger volume utilization coefficient, improve the pumping speed of the doublescrew vacuum pump, reduce the volume of a working cavity at an exhaust end, have larger content ratio and compression ratio, and are favorable for improving the ultimate vacuum degree of the vacuum pump.
Description
Technical Field
The invention relates to a doublescrew vacuum pump, in particular to a conical screw rotor suitable for a doublescrew vacuum pump.
Background
The doublescrew vacuum pump is a rotary positive displacement vacuum pump, a pair of mutually meshed screw rotors perform synchronous and opposite double rotary motion in a pump cavity to realize the periodic change of the volume of a working cavity, complete the processes of gas suction, compression and discharge, and form vacuum at an inlet of the pump; the doublescrew vacuum pump has the advantages of dry oilfree performance, stable operation, few easilydamaged parts, and low vibration and noise, and is widely applied to the fields of aviation, electronics, petrochemical industry and nuclear industry.
The vacuum pump generates a larger compression ratio in the working process, and two screw rotors which are required to be meshed with each other have a larger internal volume ratio, wherein the internal volume ratio is the ratio of the maximum closed volume to the minimum closed volume formed by the two screw rotors in the meshing process. The existing screw rotor is generated by unfolding the molded line of the axial section of the screw rotor along an axial cylindrical spiral line, the screw rotor is divided into a uniform pitch screw rotor and a variable pitch screw rotor, and the variable pitch screw rotor is more favorable for improving the pumping speed and the ultimate vacuum degree of a doublescrew vacuum pump because the internal volume ratio of the variable pitch screw rotor is greater than 1. Chinese patent publication No. CN105422448A discloses a variablepitch screw rotor with variable tooth width, which has a large ratio of suction volume to internal volume, but the parallel shaft structure has a limited effect on increasing the internal volume ratio. Chinese patent (publication No. CN205805908U) discloses a conical screw rotor and a twinscrew vacuum pump thereof, which uses a threestage conical twinscrew structure to increase the air suction volume and the internal volume ratio, but has a limited effect on improving the performance, and is not easy to ensure the sealing effect between the twinscrew rotor and the pump cavity. Chinese patent (patent No. CN 104141606a) proposes a conical twinscrew compression pump, which uses 5: 3 the driven female and male conical screw has higher compression coefficient theoretically, but the contact line of the two plane sections under the meshing condition of the crossed shafts only has a straight line, the multihead plane molded line can be incompletely meshed or not meshed under the meshing condition of the crossed shafts, and the sealing performance between the two screws cannot be ensured.
Disclosure of Invention
The invention provides a conical screw rotor of a doublescrew vacuum pump, which aims to improve the internal volume ratio formed by two screw rotors of the doublescrew vacuum pump to the maximum extent, further improve the ultimate vacuum degree of the doublescrew vacuum pump and improve the air suction quantity of the doublescrew vacuum pump. The invention adopts the spherical section to realize the correct meshing of the crossed shafts of the left conical rotor and the right conical rotor, and the radiuses of pitch circle, addendum circle and dedendum circle of the two rotors from the air suction end to the air exhaust end are all linearly reduced; under the condition of the same equivalent size, the air suction end has larger volume, and the air suction speed of the doublescrew vacuum pump is improved under the condition of the same rotating speed; the short contact line is arranged at the exhaust end, so that the vacuum degree of the doublescrew vacuum pump is ensured. The variablepitch spiral line is adopted, so that the pressure distribution of the doublescrew vacuum pump from the lowpressure end to the highpressure end is uniform, the pressure difference between working volumes is reduced, the internal leakage of the doublescrew vacuum pump is reduced, and the variablepitch spiral line has important significance for improving the comprehensive performance of the doublescrew vacuum pump.
In order to achieve the purpose, the invention adopts the following technical scheme:
a conical screw rotor of a twin screw vacuum pump comprising: the left conical screw rotor and the right conical screw rotor are both linearly conical from a lowpressure end to a highpressure end, namely the pitch circle radius, the tooth crest radius and the tooth bottom radius of the left conical screw rotor and the right conical screw rotor are all linearly reduced;
in a working meshing state, a rotating shaft OP of the left conical screw rotor and a rotating shaft OQ of the right conical screw rotor are intersected at one point, the intersection point is O, the included angle of the two rotating shafts is ∠ POQ theta, and the value range of the included angle is 0 degrees < theta <90 degrees;
the end surfaces of the left conical screw rotor and the right conical screw rotor at the highpressure end are concave spherical surfaces with the radius of R_{o}(ii) a The pitch circle radius of the left conical screw rotor and the right conical screw rotor at the highpressure end is r_{o}And satisfy
Left conical screw rotorAnd the end surface of the right conical screw rotor at the lowpressure end is an outward convex spherical surface with the radius of R_{i}(ii) a The pitch circle radius of the left conical screw rotor and the right conical screw rotor at the lowpressure end is r_{i}And satisfy
The intersection O of the rotation axis OP of the left conical screw rotor and the rotation axis OQ of the right conical screw rotor is regarded as the center of sphere, and the radius is R (R)_{o}<R<R_{i}) Making a spherical surface, wherein the intersection section of the spherical surface and the left conical screw rotor is a left spherical section, the contour line of the left spherical section consists of 4 spherical curves and a point, and the contour line sequentially comprises the following steps in the clockwise direction: a left spherical surface addendum arc AB, a left spherical surface involute BC, a left spherical surface tooth root arc CD, a left spherical surface cycloid DA and a left addendum point A;
the contour line equation of the left sphere section is as follows:
establishing a threedimensional rectangular coordinate system XYZ by taking the intersection point O as a coordinate origin, wherein a rotating shaft OP of the left conical screw rotor (1) is a Z axis; the parameter equation of the addendum arc AB of the left spherical surface is as follows:
wherein the content of the first and second substances,lambda is the addendum radius coefficient, 2 > lambda > 1; r_{2}Is a pitch circle radius, satisfies the relationship
The parameter equation of the left spherical involute BC is as follows:
wherein the content of the first and second substances,ρ_{BC}＝(1+t^{2})R_{b} ^{2}；R_{b}the radius of the involute generating circle;α is the involute starting angle;
the parameter equation of the left spherical tooth root circular arc CD is as follows:
wherein the content of the first and second substances,
the parametric equation for the left spherical cycloid DA is:
wherein the content of the first and second substances,
the intersection O of the rotation axis OP of the left conical screw rotor and the rotation axis OQ of the right conical screw rotor is regarded as the center of sphere, and the radius is R (R)_{o}<R<R_{i}) Making a spherical surface, wherein the intersection section of the spherical surface and the right conical screw rotor is a right spherical section, the profile line of the right spherical section consists of 4 curves and a point, and the right spherical section sequentially comprises the following steps in the clockwise direction: a right spherical addendum arc ab, a right spherical involute bc, a right spherical dedendum arc cd, a right spherical cycloid da and a right tooth vertex a;
the right sphere section molded line and the left sphere section molded line are completely the same in shape.
The left conical screw rotor consists of 4 tooth surfaces, and sequentially comprises the following steps: the tooth surfaces are sequentially generated by lofting a left spherical tooth crest arc AB, a left spherical involute BC, a left spherical tooth root arc CD and a left spherical cycloid DA in the molded line of the end face of the screw rotor; the right conical screw rotor consists of 4 tooth surfaces, and sequentially comprises the following steps: the tooth surfaces are sequentially generated by lofting a right spherical addendum arc ab, a right spherical involute bc, a right spherical dedendum arc cd and a right spherical cycloid da in the molded line of the end face of the screw rotor;
during working, the left conical tooth crest surface, the left conical oblique tooth surface, the left conical tooth root surface and the left conical concave tooth surface of the left conical screw rotor can be correctly meshed with the right conical tooth crest surface, the right conical oblique tooth surface, the right conical tooth root surface and the right conical concave tooth surface of the right conical screw rotor respectively.
The curve formed by the left addendum point A on the contour line of any left ball section of the left conical screw rotor is a left variablepitch spiral line L_{1}Left variable pitch helix L_{1}From the left to the circle C_{L}Clockwise spiral development and left generation circle C_{L}The radius of the valve is linearly reduced from the lowpressure end to the highpressure end, namely the equation is satisfied:
in the formula: tau is_{1}left helix flare angle, rad; r_{0}high pressure end face helix generating circle radius, mm; r is_{L}helix radius reduction rate factor;
left variable pitch helix L_{1}Pitch P of_{L}The size of the highvoltage terminal is continuously reduced from the lowvoltage terminal to the highvoltage terminal;
the curve formed by the right tooth top point a on any right spherical section contour line of the right conical screw rotor is a right variable pitch helix L_{2}Right variable pitch helix L_{2}From the right to circle C_{R}Counterclockwise spiral expansion and generation, right generation circle C_{R}Is linearly reduced from the lowpressure end to the highpressure end, and the radius is equal to the left generating circle C_{L}The radius of the steel wire is kept consistent;
right variable pitch helix L_{2}Pitch P of_{R}Is continuously reduced from the lowpressure end to the highpressure end and is connected with the left variablepitch spiral line L_{1}Pitch P of_{L}And the consistency is maintained.
The pump cavity in the pump body can accommodate the crossshaft screw; the pump body air inlet I is arranged at the position, close to the lowpressure end, of the pump cavity; a pump body exhaust port P is arranged at the position, close to the highpressure end, of the pump cavity;
the pump body consists of a left rotor pump cavity and a right rotor pump cavity, wherein a central axis OM of the left rotor pump cavity and a central axis ON of the right rotor pump cavity are intersected at a point O, and the included angle ∠ MON between the central axis OM and the central axis ON is theta;
the left rotor pump cavity and the right rotor pump cavity are in linear conical shapes; from the lowpressure end to the highpressure end, the wall radii of the left rotor pump cavity and the right rotor pump cavity are linearly reduced;
the left rotor pump cavity and the right rotor pump cavity are positioned on the same spherical surface Q at the lowpressure end_{1}Spherical surface Q_{1}Has a radius of R_{1}The pump chamber radial radius of the left and right rotor pump chambers at the low pressure end is r_{2}And satisfies the relationship:wherein, k is a wall radius coefficient;
the left rotor pump cavity and the right rotor pump cavity are positioned on the same spherical surface Q at the highpressure end_{2}Spherical surface Q_{2}Radius R_{1}The pump cavity radial radius of the left and right rotor pump cavities at the high pressure end is r_{2}And satisfies the relationship:
during operation, the left and right conical screw rotors are driven by a pair of nonorthogonal gears: the left transmission gear and the right transmission gear are driven, and the included angle of the rotating shafts of the two nonorthogonal gears is theta; in the assembled state, the rotation axis OP of the left conical screw rotor and the rotation axis of the left transmission gear coincide, and the rotation axis OQ of the right conical screw rotor and the rotation axis of the right transmission gear coincide.
A conical twinscrew vacuum pump uses a left conical screw rotor and a right conical screw rotor.
The invention has the beneficial effects that:
① radius of circular arc of top tooth on screw rotor_{1}And the radius R of the circular arc of the tooth bottom_{3}The screw pitches are gradually reduced from the lowpressure end (IIII) to the highpressure end (II) of the screw rotor, so that the volume of a working cavity at an exhaust end is reduced, the content ratio and the compression ratio are larger, and the ultimate vacuum degree of a vacuum pump is favorably improved;
② from the low pressure end (IIII) to the high pressure end (II), the length of the screw rotor space contact line is gradually shortened, effectively reducing the interstage leakage of the screw rotor;
③ the screw rotor has short axial dimension and compact structure;
④ the screw rotor is subjected to a small axial force of gas.
Drawings
FIG. 1 is a view of the engagement of two screw rotors.
Fig. 2 is a threedimensional view of the left conical screw rotor (1).
Fig. 3 is a threedimensional view of the right conical screw rotor (2).
FIG. 4 is a schematic view of the engagement of the spherical sections of two screw rotors.
Fig. 5 is a curved view of the left conical screw rotor (1).
Fig. 6 is a curved view of the right conical screw rotor (2).
Fig. 7 is a structure diagram of a pump body of the doublescrew vacuum pump.
Fig. 8 is an assembly view of a twin screw vacuum pump.
In the figure: 1left conical screw rotor; 2right conical screw rotor; ointersection point of rotating shafts of the two screws; theta is the included angle of the rotating shafts of the two screws; ro is the radius of the end surface of the concave ball at the highpressure end (II) of the left conical screw rotor (1) and the right conical screw rotor (2); r is_{o}pitch radii of the left conical screw rotor (1) and the right conical screw rotor (2) at the high pressure end (ii); r_{i}the radius of the outer convex spherical end surface of the left conical screw rotor (1) and the right conical screw rotor (2) at the low pressure end (iiii); r is_{i}left conical screw rotor (1) and right conical screw rotor (2) at low pressure end (II)pitch circle radius at II). Rradius of spherical surface with O as center of sphere, R_{o}<R<R_{i}。
Detailed Description
The invention is further described with reference to the following figures and examples.
As shown in fig. 1, the twoscrew rotor meshing diagram includes: the left conical screw rotor 1 and the right conical screw rotor 2 are respectively in a linear conical shape from a lowpressure end IIII to a highpressure end II, namely the pitch circle radius, the tooth crest radius and the tooth bottom radius of the left conical screw rotor 1 and the right conical screw rotor 2 are all linearly reduced;
in the working engagement state, the rotating shaft OP of the left conical screw rotor 1 and the rotating shaft OQ of the right conical screw rotor 2 intersect at one point, the intersection point is O, the included angle between the two rotating shafts is ∠ POQ ═ θ, and the value range is 0 ° < θ <90 °;
as shown in FIG. 2, which is a threedimensional view of the left conical screw rotor 1, the end surface of the left conical screw rotor 1 at the highpressure end II is a concave spherical surface with a radius R_{o}(ii) a The pitch circle radius of the left conical screw rotor 1 at the highpressure end II is r_{o}And satisfyThe end surface of the left conical screw rotor 1 at the lowpressure end IIII is an outward convex spherical surface with the radius R_{i}(ii) a The pitch circle radius of the left conical screw rotor 1 at the lowpressure end IIII is r_{i}And satisfy
As shown in FIG. 3, which is a threedimensional view of the right conical screw rotor 2, the end surface of the right conical screw rotor 2 at the highpressure end II is a concave spherical surface with a radius R_{o}(ii) a The pitch circle radius of the right conical screw rotor 2 at the highpressure end II is r_{o}And satisfyRight conical screw rotor 2 at low pressure end IIIIThe end surface is a convex spherical surface with a radius of R_{i}(ii) a The pitch circle radius of the right conical screw rotor 2 at the lowpressure end IIII is r_{i}And satisfy
As shown in FIG. 4, the twoscrew rotor spherical section meshing timing diagram is obtained by taking the intersection O of the rotation axis OP of the left conical screw rotor 1 and the rotation axis OQ of the right conical screw rotor 2 as the center of sphere and the radius R (R)_{o}<R<R_{i}) Making a spherical surface, wherein the intersection section of the spherical surface and the left conical screw rotor 1 is a left spherical section 101, the profile line of the left spherical section 101 consists of 4 spherical curves and a point, and the curve lines sequentially comprise the following components in the clockwise direction: a left spherical surface addendum arc AB, a left spherical surface involute BC, a left spherical surface tooth root arc CD, a left spherical surface cycloid DA and a left addendum point A;
the contour line equation for the lefthand ball section 101 is as follows:
establishing a threedimensional rectangular coordinate system XYZ by taking the intersection point O as a coordinate origin, wherein a rotating shaft OP of the left conical screw rotor 1 is a Z axis; the parameter equation of the addendum arc AB of the left spherical surface is as follows:
wherein the content of the first and second substances,lambda is the addendum radius coefficient, 2 > lambda > 1; r_{2}Is a pitch circle radius, satisfies the relationship
The parameter equation of the left spherical involute BC is as follows:
wherein the content of the first and second substances,ρ_{BC}＝(1+t^{2})R_{b} ^{2}；R_{b}the radius of the involute generating circle;α is the involute starting angle;
the parameter equation of the left spherical tooth root circular arc CD is as follows:
wherein the content of the first and second substances,
the parametric equation for the left spherical cycloid DA is:
wherein the content of the first and second substances,
the intersection O of the rotation axis OP of the left conical screw rotor 1 and the rotation axis OQ of the right conical screw rotor 2 is the center of sphere and the radius is R (R)_{o}<R<R_{i}) Making a spherical surface, wherein the intersection section of the spherical surface and the right conical screw rotor 2 is a right spherical section 201, the contour line of the right spherical section 201 consists of 4 curves and a point, and the right spherical section and the right conical screw rotor sequentially comprises the following steps in the clockwise direction: a right spherical addendum arc ab, a right spherical involute bc, a right spherical dedendum arc cd, a right spherical cycloid da and a right tooth vertex a;
the shape of the right spherical crosssectional profile 201 is identical to that of the left spherical crosssectional profile 101.
As shown in fig. 5, a curved surface view is formed for the left conical screw rotor 1. The left conical screw rotor 1 consists of 4 tooth surfaces, which are sequentially as follows: the tooth surface comprises a left conical tooth crest 11, a left conical oblique tooth surface 12, a left conical tooth root surface 13 and a left conical concave tooth surface 14, wherein the tooth surfaces are sequentially generated by lofting a left spherical tooth crest arc AB, a left spherical involute BC, a left spherical tooth root arc CD and a left spherical cycloid DA in the molded line of the end surface of the screw rotor;
as shown in fig. 6, the right conical screw rotor 2 is formed into a curved surface view. The right conical screw rotor 2 consists of 4 tooth surfaces, which are sequentially: the tooth surface is sequentially generated by lofting a right spherical tooth crest circular arc ab, a right spherical involute bc, a right spherical tooth root circular arc cd and a right spherical cycloid da in the molded line of the end face of the screw rotor;
in operation, the left conical tooth crest 11, the left conical oblique tooth flank 12, the left conical tooth root surface 13 and the left conical concave tooth flank 14 of the left conical screw rotor 1 can be correctly meshed with the right conical tooth crest 21, the right conical oblique tooth flank 22, the right conical tooth root surface 23 and the right conical concave tooth flank 24 of the right conical screw rotor 2 respectively.
The curve formed by the left addendum point A on the contour line of any left ball section 101 of the left conical screw rotor 1 is a left variablepitch spiral line L_{1}Left variable pitch helix L_{1}From the left to the circle C_{L}Clockwise spiral development and left generation circle C_{L}The radius of the highvoltage end II is linearly reduced from the lowvoltage end IIII to the highvoltage end II, and the equation is satisfied:
in the formula: tau is_{1}left helix flare angle, rad; r_{0}high pressure end face helix generating circle radius, mm; r is_{L}helix radius reduction rate factor;
left variable pitch helix L_{1}Pitch P of_{L}The voltage from the lowvoltage end II to the highvoltage end I is continuously reduced;
the curve formed by the right tooth top point a on the contour line of any right spherical section 201 of the right conical screw rotor 2 is a right variablepitch spiral line L_{2}Right variable pitch helix L_{2}From the right to the circleC_{R}Counterclockwise spiral expansion and generation, right generation circle C_{R}The radius of the left generation circle C is linearly reduced from the lowvoltage end IIII to the highvoltage end II_{L}The radius of the steel wire is kept consistent;
right variable pitch helix L_{2}Pitch P of_{R}Continuously reduced from the lowpressure end IIII to the highpressure end II and connected with the left variablepitch spiral line L_{1}Pitch P of_{L}Keeping consistent;
as shown in fig. 7, which is a structure diagram of a pump body of a doublescrew vacuum pump, a pump cavity in the pump body can accommodate a crossshaft screw; the pump body air inlet I is arranged at the position, close to the lowpressure end IIII, of the pump cavity; an air outlet P of the pump body 3 is arranged at a position, close to a highpressure end II, of the pump cavity;
the pump body 3 consists of a left rotor pump cavity 301 and a right rotor pump cavity 302, wherein a central axis OM of the left rotor pump cavity 301 and a central axis ON of the right rotor pump cavity 302 are intersected at a point O, and the included angle ∠ MON between the central axis OM and the central axis ON is theta;
the left rotor pump chamber 301 and the right rotor pump chamber 302 are linearly tapered; from the lowpressure end iiii to the highpressure end ii, the wall radii of the left rotor pump chamber 301 and the right rotor pump chamber 302 decrease linearly;
the left rotor pump chamber 301 and the right rotor pump chamber 302 are located on the same spherical surface Q at the lowpressure end iiii_{1}Spherical surface Q_{1}Has a radius of R_{1}The pump chamber radial radii of the left rotor pump chamber 301 and the right rotor pump chamber 302 at the lowpressure end iiii are r_{2}And satisfies the relationship:wherein, k is a wall radius coefficient;
the left rotor pump chamber 301 and the right rotor pump chamber 302 are located on the same spherical surface Q at the high pressure side ii_{2}Spherical surface Q_{2}Radius R_{1}The pump chamber radial radii of the left rotor pump chamber 301 and the right rotor pump chamber 302 at the high pressure end II are r_{2}And satisfies the relationship:
as shown in fig. 8, which is a view of a twinscrew vacuum pump assembly, during operation, the left conical screw rotor 1 and the right conical screw rotor 2 are formed by a pair of nonorthogonal gears: the left transmission gear 4 and the right transmission gear 5 are driven, and the included angle of the rotating shafts of the two nonorthogonal gears is theta; in the assembled state, the rotation axis OP of the left conical screw rotor 1 and the rotation axis of the left transmission gear 4 coincide, and the rotation axis OQ of the right conical screw rotor 2 and the rotation axis of the right transmission gear 5 coincide.
Although the embodiments of the present invention have been described with reference to the accompanying drawings, it is not intended to limit the scope of the present invention, and it should be understood by those skilled in the art that various modifications and variations can be made without inventive efforts by those skilled in the art based on the technical solution of the present invention.
Claims (4)
1. A conical screw rotor of a twin screw vacuum pump comprising: left side conical screw rotor (1), right conical screw rotor (2), characterized by: the left conical screw rotor (1) is in a linear conical shape from the lowpressure end (IIII) to the highpressure end (II), namely the pitch circle radius, the tooth crest radius and the tooth bottom radius of the left conical screw rotor (1) are linearly reduced from the lowpressure end (IIII) to the highpressure end (II); the right conical screw rotor (2) is in a linear conical shape from the lowpressure end (IIII) to the highpressure end (II), namely the pitch circle radius, the tooth top radius and the tooth bottom radius of the right conical screw rotor (2) are linearly reduced from the lowpressure end (IIII) to the highpressure end (II);
the end surfaces of the left conical screw rotor (1) and the right conical screw rotor (2) at the highpressure end (II) are concave spherical surfaces, and the radiuses of the concave spherical surfaces are R_{o}(ii) a The end surfaces of the left conical screw rotor (1) and the right conical screw rotor (2) at the lowpressure end (IIII) are convex spherical surfaces with the radiuses of R_{i}；
In the working meshing state, the rotating shaft OP of the left conical screw rotor (1) and the rotating shaft OQ of the right conical screw rotor (2) intersect at one point, and the intersection point is O; with the intersection O as the center of sphere and R (R)_{o}<R<R_{i}) The radius is made into a spherical surface, and the intersection section of the spherical surface and the left conical screw rotor (1) is a left spherical section(101) The contour line of the left spherical section (101) consists of 4 spherical curves and a point, and the contour line sequentially comprises the following steps in the clockwise direction: a left spherical surface addendum arc AB, a left spherical surface involute BC, a left spherical surface tooth root arc CD, a left spherical surface cycloid DA and a left addendum point A;
the contour line equation of the left spherical section (101) is as follows:
establishing a threedimensional rectangular coordinate system XYZ by taking the intersection point O as a coordinate origin, wherein a rotating shaft OP of the left conical screw rotor (1) is a Z axis; the parameter equation of the addendum arc AB of the left spherical surface is as follows:
wherein R is a spherical radius;lambda is the addendum radius coefficient, 2 > lambda > 1; r_{2}Is a pitch circle radius, satisfies the relationship
The parameter equation of the left spherical involute BC is as follows:
wherein the content of the first and second substances,ρ_{BC}(t)＝(1+t^{2})R_{b} ^{2}；R_{b}the radius of the involute generating circle;α is the involute starting angle;
the parameter equation of the left spherical tooth root circular arc CD is as follows:
wherein the content of the first and second substances,
the parametric equation for the left spherical cycloid DA is:
wherein the content of the first and second substances,
the intersection O of the rotation axis OP of the left conical screw rotor (1) and the rotation axis OQ of the right conical screw rotor (2) is used as the center of sphere, and R (R)_{o}<R<R_{i}) The spherical surface is made as a radius, the intersection section of the spherical surface and the right conical screw rotor (2) is a right spherical section (201), the contour line of the right spherical section (201) consists of 4 curves and a point, and the right spherical section and the right conical screw rotor sequentially comprise the following components in the clockwise direction: a right spherical addendum arc ab, a right spherical involute bc, a right spherical dedendum arc cd, a right spherical cycloid da and a right tooth vertex a; the right spherical section molded line (201) is the same as the left spherical section molded line (101).
2. The conical screw rotor of a twinscrew vacuum pump as defined in claim 1, wherein: the left conical screw rotor (1) consists of 4 tooth surfaces, and sequentially comprises the following steps: the left conical tooth crest (11), the left conical oblique tooth flank (12), the left conical tooth root surface (13) and the left conical concave tooth flank (14) are sequentially generated by a left spherical tooth crest arc AB, a left spherical involute BC, a left spherical tooth root arc CD and a left spherical cycloid DA in a left spherical section (101) of the left conical screw rotor (1); the right conical screw rotor (2) consists of 4 tooth surfaces, and sequentially comprises the following steps: the tooth surface is sequentially generated by a right spherical addendum arc ab, a right spherical involute bc, a right spherical dedendum arc cd and a right spherical cycloid da in a right spherical section (201) of the right conical screw rotor (2);
in the synchronous and asynchronous cross shaft transmission work, the two screw rotors can be correctly meshed, and the left conical tooth crest (11), the left conical oblique tooth flank (12), the left conical tooth root surface (13) and the left conical concave tooth flank (14) of the left conical screw rotor (1) can be correctly meshed with the right conical tooth crest (21), the right conical oblique tooth flank (22), the right conical tooth root surface (23) and the right conical concave tooth flank (24) of the right conical screw rotor (2) respectively.
3. The conical screw rotor of a twinscrew vacuum pump as defined in claim 1, wherein: establishing a threedimensional rectangular coordinate system XYZ by taking the intersection point O as a coordinate origin, wherein a rotating shaft OP of the left conical screw rotor (1) is a Z axis;
the curve formed by the left addendum point A on the contour line of any left ball section (101) of the left conical screw rotor (1) is a left variablepitch spiral line L_{1}Left variable pitch helix L_{1}From the left to the circle C_{L}Clockwise spiral development and left generation circle C_{L}The radius of the highpressure end (II) linearly decreases from the lowpressure end (IIII);
left variable pitch helix L_{1}The equation for the occurrence of the circle is:
in the formula: tau is_{1}left helix flare angle, rad; r_{0}high pressure end face helix generating circle radius, mm; r is_{L}helix radius reduction rate factor;
left variable pitch helix L_{1}Pitch P of_{L}The voltage from the low voltage end (IIII) to the high voltage end (II) is continuously reduced;
the curve formed by the right tooth top point a on the contour line of any right spherical section (201) of the right conical screw rotor (2) is a right variable pitch helix L_{2}Right variable pitch helix L_{2}From the right to circle C_{R}Counterclockwise spiral expansion and generation, right generation circle C_{R}The radius of the valve is linearly reduced from the lowpressure end (IIII) to the highpressure end (II), and the radius is equal to the leftGenerating circle C_{L}The radius of the steel wire is kept consistent;
right variable pitch helix L_{2}Pitch P of_{R}Continuously decreasing from the low pressure end (IIII) to the high pressure end (II) and forming a helical line L with a variable left pitch_{1}Pitch P of_{L}And the consistency is maintained.
4. A conical doublescrew vacuum pump is characterized in that: use of a left conical screw rotor (1) and a right conical screw rotor (2) according to claim 1.
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Cited By (4)
Publication number  Priority date  Publication date  Assignee  Title 

CN111749889A (en) *  20200522  20201009  浙江珂勒曦动力设备股份有限公司  Screw vacuum pump with taper 
CN112610474A (en) *  20201222  20210406  金迈思液压设备（天津）有限公司  Conical rotor doublescrew pump with bilateral exhaust 
CN113153742A (en) *  20210224  20210723  西安交通大学  Variableline doublescrew rotor and design method thereof 
CN113357151A (en) *  20210712  20210907  西安交通大学  Externalmeshing conical doublescrew compressor rotor driven by intersecting shafts and compressor 

2019
 20191224 CN CN201911347029.6A patent/CN110821835A/en active Pending
Cited By (5)
Publication number  Priority date  Publication date  Assignee  Title 

CN111749889A (en) *  20200522  20201009  浙江珂勒曦动力设备股份有限公司  Screw vacuum pump with taper 
CN112610474A (en) *  20201222  20210406  金迈思液压设备（天津）有限公司  Conical rotor doublescrew pump with bilateral exhaust 
CN113153742A (en) *  20210224  20210723  西安交通大学  Variableline doublescrew rotor and design method thereof 
CN113153742B (en) *  20210224  20220712  西安交通大学  Variableline doublescrew rotor and design method thereof 
CN113357151A (en) *  20210712  20210907  西安交通大学  Externalmeshing conical doublescrew compressor rotor driven by intersecting shafts and compressor 
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