A convex-flat conjugate three-twisted blade rotor volume pair and helical gear power pair

Abstract

A convex-flat conjugated three-twisted-blade rotor volumetric pair and a helical-tooth power pair, wherein the three-twisted-blade rotor volumetric pair comprises two non-contact three-twisted-blade rotors with the same end face profile, opposite spiral directions and the same spiral angle; the helical-tooth power pair comprises two contact-type standard-open-line quasi-asymmetric cylindrical helical gears with the same end face profile, opposite spiral directions and the same spiral angle; the three-twisted-blade rotor volumetric pair and the helical-tooth power pair have the same end face pitch circle radius and spiral angle, and the three-twisted-blade rotor and the standard cylindrical helical gear on the same axis have opposite spiral directions. A coupled combination of a three-twisted-blade rotor volumetric pair with pitch-chord height conjugation and its helical-tooth power pair has a larger shape coefficient and volume utilization coefficient, a smaller radial leakage rate and a convex-flat conjugated leakage rate, and has the beneficial effects of no theoretical flow pulsation and axial force.

Description

Technical Field

[0001] The present invention belongs to the technical field of rotor pumps, and specifically relates to a three-twisted blade profile structure with high volumetric efficiency, no theoretical pulsation and convex-flat conjugation as a volumetric auxiliary rotor, and a coupling determination of the mutual offset of theoretical axial force and the volumetric auxiliary rotor as a power auxiliary helical gear. Background Art

[0002] The rotor pump is a type of positive displacement pump that uses two identical rotors, i.e. rotor volume pairs, to transport the medium to the outlet through the inlet vacuum suction generated during the non-contact conjugate rotation process. The rotational power of the rotor pair is provided by another helical gear power pair with a helical angle of 8° to 20° in the axial direction. High volumetric efficiency and low noise are the two main goals of the rotor pump, and the American Petroleum Institute API676 standard and SH / T 3151-2013 Petrochemical Rotor Pump Engineering Technical Specifications also have clear requirements for this.

[0003] High volumetric efficiency is mainly achieved by maximizing the volume utilization coefficient and minimizing internal leakage. The maximization of the volume utilization coefficient is equivalent to the maximization of the rotor shape coefficient (= rotor top radius / end pitch radius). The flow pulsation and pressure pulsation caused by the contour structure are the main sources of noise. Although a large number of blades or twisted blades can reduce flow pulsation, a large number of blades has limited improvement in pulsation and also greatly reduces the rotor shape coefficient, which is often an indirect method that "does not make up for the loss". Although twisted blades increase the difficulty of processing, they can greatly reduce flow pulsation and pressure pulsation without changing the shape coefficient, and even achieve a theoretical pulsation-free effect. It is a "fast and effective" direct method. For ordinary rotors whose shape coefficient is completely determined by the rotor conjugate contour segment, the conjugate contour segments with the maximum shape coefficient are arcs and involutes, and their upper limits are 1.6699, 1.4770, 1.3680 and 1.6177, 1.4638, 1.3655 for 2-blade, 3-blade, and 4-blade, respectively. Among them, the conjugate contour segment is often composed of two contour segments: the outer conjugate of the pitch circle and the inner conjugate of the pitch circle.

[0004] The internal leakage of the rotor pump mainly consists of radial leakage, axial leakage and conjugate zone leakage. Although the axial leakage is little affected by the rotor profile structure, the radial equal-gap sealing with the inner surface of the pump casing and the conjugate zone multi-point sealing (similar to the multiple meshing points in the gear transmission with overlap > 1) with the profile improvement of the convex-flat conjugate mode can effectively suppress radial leakage and conjugate leakage.

[0005] Although the multi-point sealing of the conjugate area of ​​the straight-vane rotor pair is prone to cause pressure shocks in the medium therein similar to the oil trapped phenomenon in a gear pump, the axial conjugate gap length of the twisted-vane rotor is variable. As long as the axial staggered angle and the aspect ratio (= axial width / end pitch diameter) of the contours at both ends are properly designed, and the non-contact gap between the rotors and the rotation speed are not too high, the twisted-vane rotor pair will not cause the so-called "oil trapped phenomenon". However, the harmful axial force it generates needs to be offset or partially offset, otherwise it will increase the friction loss in the device and shorten the service life. Summary of the invention

[0006] The present invention aims at achieving the higher volumetric efficiency and the absence of theoretical flow pulsation and axial force expected in the background technology of rotor pumps. Based on the special geometric relationship of the conjugate contour segment within the pitch circle using the half-blade pitch arc chord height line (referred to as the half-blade pitch chord height), and the structural design needs of the 60° blade twisting angle of the two end contours and the pump casing inclusion angle required for the absence of theoretical flow pulsation, the present invention provides a three-twisted blade rotor with an end face contour having a larger shape coefficient, radial equal sealing clearance, multi-point sealing in the convex-flat conjugate area, and a 60° blade twisting angle of the two end face contours and a helical angle between 19.5° and 20.5°, as well as the determination of a standard cylindrical helical gear with a helical angle between 19.5° and 20.5° in which the theoretical axial force and the volume pair of the three-twisted blade rotor offset each other.

[0007] To achieve the above purpose, the technical solution of the present invention is as follows:

[0008] A convex-flat conjugated three-twisted blade rotor volume pair and a helical gear power pair, characterized in that:

[0009] 3-twisted blade rotor volume pair: includes two sets of non-contact 3-twisted blade rotors with the same end face profile, opposite spiral directions and the same spiral angle;

[0010] Helical gear power pair: includes two contacting standard cylindrical helical gears with the same end face profile, opposite spiral directions and the same spiral angle;

[0011] The end face pitch circle radius and helical angle of the 3-twisted blade rotor volume pair and the helical gear power pair are the same, and the helical directions of the 3-twisted blade rotor and the standard cylindrical helical gear on the same axis are opposite.

[0012] The helix angles of the three-twisted blade rotor and the standard cylindrical helical gear are 19.5° to 20.5°, wherein the number of teeth and the normal module of the standard cylindrical helical gear are first determined by the helix angle of 20°, and then the specific helix angle between 19.5° and 20.5° is determined by the equal end pitch circle radius of the three-twisted blade rotor and the standard cylindrical helical gear.

[0013] The twisted blade stagger angle of the two end contours of the three-twisted blade rotor is 60°, and the axial stagger angle of the two end contours of the standard cylindrical helical gear is determined by the number of teeth. Specifically, the axial stagger angle of the two end contours of the standard cylindrical helical gear satisfies the numerical value:

[0014] The axial staggered angle of the profiles at both ends of a standard cylindrical helical gear = 360° / number of teeth.

[0015] According to the 60° staggered blade rule of the two ends of the 3-twisted blade rotor and the helix angle ξ between 19.5° and 20.5°, the width-to-diameter ratio of the 3-twisted blade rotor is

[0016]

[0017] The end face pitch circle radius r is uniquely determined by the known rated flow Q, rated speed n, volumetric efficiency η of the rotor pump, the volume utilization coefficient λ of the rotor, the shape coefficient ε and the helix angle ξ between 19.5° and 20.5°.

[0018]

[0019] The number of teeth z and normal module m of the standard cylindrical helical gear n First, based on the helix angle ξ of 20°, the end pitch radius r(ξ), the standard normal pressure angle of 20°, the tooth top height coefficient of 1, and the normal top clearance coefficient of 0.25, according to the gear design method of "GB / T 1357-2008 Module of cylindrical gears for general machinery and heavy machinery" and "GB1356-88 Basic tooth profile of involute cylindrical gears", combined with the following formula

[0020] 2r(ξ)×cosξ=m n z≈2r(20°)×cos(20°) (3)

[0021] Then, the specific helix angle ξ between 19.5° and 20.5° is determined by the approximate equality of the end face pitch radius of the 3-twist blade rotor and the standard involute cylindrical helical gear. Finally, the corresponding specific aspect ratio φ is determined by equations (1) and (2): rotor (ξ) and end pitch radius r(ξ);

[0022] According to the axial staggered angle rule of 360° / number of teeth of the two ends of the helical gear and the specific helix angle ξ just obtained between 19.5° and 20.5°, the width-to-diameter ratio of the standard cylindrical helical gear is

[0023]

[0024] Determine, where the end face overlap ε t According to the obtained number of teeth z and normal module m n, the specific helix angle ξ between 19.5° and 20.5° just calculated and the standard normal pressure angle 20°, tooth top height coefficient 1, and normal top clearance coefficient 0.25 are uniquely determined.

[0025] The theoretical contour of the half-blade end face of the three-twist blade rotor is composed of six parts, namely, the top concentric arc, the outer transition contour segment, the outer conjugate contour segment, the half-blade node chord height, the inner transition contour segment and the valley concentric arc. The corresponding endpoints and connection points are, in order, the peak point, the vertex, the outer starting point, the mid-node, the inner starting point, the root point and the valley point on the valley symmetry axis. Among them, the two boundaries of the half-blade contour are the peak symmetry axis and the valley symmetry axis, the angle between the peak symmetry axis and the valley symmetry axis is 60°, and the chord height of the node arc between the peak symmetry axis and the valley symmetry axis is the half-blade node chord height; the center angle of the node arc from the intersection of the normal line at the vertex of the outer transition contour segment and the node circle to the mid-node is the top node angle β;

[0026] The outer conjugate contour segment is the conjugate trajectory of the half blade chord height of the paired rotor on the rotor; the outer transition contour segment is the sweep trajectory of the inner starting point of the paired rotor on the rotor; the inner transition contour segment is the sweep trajectory of the vertex of the paired rotor on the rotor; the top concentric arc and the valley concentric arc are two arcs with the rotor center as the circle center, rε and r×(2-ε) as the radii, and the center angles are both the top sealing angle α;

[0027] The shape coefficient ε, the top sealing angle α and the volume utilization coefficient λ of the rotor are all determined by the top pitch angle β through

[0028]

[0029] It is uniquely determined that the relevant data under β=45° to 55.29° are shown in Table 1, and the shape coefficient of the three-twisted blade rotor is much larger than the 1.477 upper limit shape coefficient of the existing ordinary circular arc rotor with the same number of blades. Therefore, the present invention achieves a greater shape coefficient;

[0030] Table 1 Shape coefficient, top sealing angle and volume utilization coefficient at top section angles of 45° to 55.29°

[0031]

[0032] The three-twisted blade rotor volume pair will have a total of 5 sealing points of "2 conjugate points + 2 vertices + 1 concentric arc" in the interval [0, α), a total of 3 sealing points of "2 conjugate points + 1 vertex" in the interval (α, β-30°), and a sealing point of "1 conjugate point" in the interval (β-30°, 30°). Compared with a common rotor with only one sealing point throughout the entire process, the present invention achieves a smaller convex-flat conjugate leakage rate, and coupled with the radial equal gap sealing of the entire blade 2α top sealing angle, the present invention achieves a smaller radial leakage rate; compared with the prior art, the present invention has the following beneficial effects:

[0033] A three-twisted blade rotor volume pair and a helical gear power pair with half-blade pitch chord height conjugate have a larger shape coefficient and volume utilization coefficient, a smaller radial leakage rate and a convex-flat conjugate leakage rate, and have the beneficial effects of no theoretical flow pulsation and axial force. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] Other features, objectives and advantages of the present invention will become more apparent from a reading of the detailed description of non-limiting embodiments made with reference to the following accompanying drawings.

[0035] Figure 1 It is a coaxial schematic diagram of the 3-twisted blade rotor volume pair and the helical gear power pair.

[0036] Figure 2 Schematic diagram of the half-blade profile structure of a 3-twisted blade rotor.

[0037] Figure 3 Schematic diagram of the identification of the number of sealing points in different intervals.

[0038] In the figure: O, rotor center, O', paired rotor center, 0, peak point, 1, vertex, 2, outer starting point, 3, mid-node, 4, inner starting point, 5, root point, 6, valley point, O0, peak symmetry axis, O6, valley symmetry axis, 01, top concentric arc, 12, outer transition contour segment, 23, outer conjugate contour segment, 34, half-blade chord height, 45, inner transition contour segment, 56, valley concentric arc, r, end face pitch circle radius, ε, shape coefficient, α, top sealing angle, β, top pitch angle, 7, rotor volume pair, 8, helical gear power pair, 9, driving shaft, 10, driven shaft. DETAILED DESCRIPTION

[0039] In order to make the technical means, creative features, objectives and effects achieved by the present invention easy to understand, the present invention is further explained below in conjunction with specific implementation methods.

[0040] like Figure 1 , 2 , 3, to achieve the above purpose, the technical solution of the present invention is as follows:

[0041] A convex-flat conjugated three-twisted blade rotor volume pair and a helical gear power pair, characterized in that:

[0042] 3-twisted blade rotor volume pair: includes two sets of non-contact 3-twisted blade rotors with the same end face profile, opposite spiral directions and the same spiral angle;

[0043] Helical gear power pair: includes two contacting standard cylindrical helical gears with the same end face profile, opposite spiral directions and the same spiral angle;

[0044] The end face pitch circle radius and helical angle of the 3-twisted blade rotor volume pair and the helical gear power pair are the same, and the helical directions of the 3-twisted blade rotor and the standard cylindrical helical gear on the same axis are opposite.

[0045] The twisted blade stagger angle of the two end contours of the three-twisted blade rotor is 60°, and the axial stagger angle of the two end contours of the standard cylindrical helical gear is determined by the number of teeth. Specifically, the axial stagger angle of the two end contours of the standard cylindrical helical gear satisfies the numerical value:

[0046] The axial staggered angle of the profiles at both ends of a standard cylindrical helical gear = 360° / number of teeth.

[0047] The theoretical profile of the half blade end face of the three-twist blade rotor is composed of six parts, namely, the top concentric arc 01, the outer transition contour segment 12, the outer conjugate contour segment 23, the half blade section chord height 34, the inner transition contour segment 45 and the valley concentric arc 56. The corresponding endpoints and connection points are, in order, the peak point 0 located on the peak symmetry axis, the vertex 1, the outer starting point 2, the midpoint 3, the inner starting point 4, the root point 5 and the valley point 6 located on the valley symmetry axis. Among them, the two boundaries of the half-lobe contour are the peak symmetry axis O0 and the valley symmetry axis O6, the angle between the peak symmetry axis O0 and the valley symmetry axis O6 is 60°, and the chord height of the nodal arc between the peak symmetry axis O0 and the valley symmetry axis O6 is the half-lobe nodal chord height 34; the nodal arc center angle from the intersection of the normal line and the nodal circle at the vertex of the outer transition contour segment 12 to the midpoint 3 is the vertex nodal angle β; the outer transition contour segment 12 is the sweep trajectory of the known inner starting point 4 of the paired rotor on the rotor; the outer conjugate contour segment 23 is the conjugate trajectory of the known half-lobe nodal chord height 34 on the paired rotor on the rotor; the inner transition contour segment 45 is the sweep trajectory of the known vertex 1 on the paired rotor on the rotor;

[0048] Example: Rated flow rate 10 10 mm 3 / min, rated speed of 500 rpm, volumetric efficiency of 85%, and top pitch angle β = 50.8°, shape coefficient ε = 1.60, top seal angle α = 4°, volume utilization coefficient λ = 0.57 in Table 1, the shape coefficient of the three-twisted blade rotor is much larger than the 1.477 upper limit shape coefficient of the existing ordinary arc rotor with the same number of blades, so the present invention achieves a maximized shape coefficient;

[0049] The number of teeth z and normal module m of the standard cylindrical helical gear n First, based on the helix angle ξ of 20°, the end pitch radius r(ξ), the standard normal pressure angle of 20°, the tooth top height coefficient of 1, and the normal top clearance coefficient of 0.25, according to the gear design method of "GB / T 1357-2008 Module of cylindrical gears for general machinery and heavy machinery" and "GB1356-88 Basic tooth profile of involute cylindrical gears", combined with the following formula

[0050]

[0051] The approximate equality of n =5, z = 97, and then the specific helix angle ξ = 20.25° between 19.5° and 20.5° is determined by the absolute equality of the end face pitch radius of the 3-twist blade rotor and the standard involute cylindrical helical gear. Finally, the corresponding rotor width-to-diameter ratio φ is determined by equations (1), (2), and (4). rotor (ξ)=1.419、end face pitch radius r(ξ)=258.48mm、end face overlap ε t =1.672 and the aspect ratio of the helical gear φ gear (ξ)=0.147; the top concentric arc 01 and the valley concentric arc 56 are two arcs with the rotor center O as the center, rε=258.48×1.6=413.568mm, r(2-ε)=258.48×(2-1.6)=103.392mm as the radius, and the central angle α=4°;

[0052] The three-twisted blade rotor volume pair will have a total of 5 sealing points of "2 conjugate points + 2 vertices + 1 concentric arc" in the interval [0, 4°), a total of 3 sealing points of "2 conjugate points + 1 vertex" in the interval (4°, 20.8°), and a sealing point of "1 conjugate point" in the interval (20.8°, 30°). Compared with an ordinary rotor with only 1 sealing point throughout the entire process, the multi-point sealing interval ratio reaches 69.3%, so the present invention achieves a smaller convex-flat conjugate leakage rate, plus the radial equal gap seal of the whole blade with a top sealing angle of 2α=8°, so the present invention achieves a smaller radial leakage rate;

[0053] The above shows and describes the basic principles and main features of the present invention and the advantages of the present invention. It is obvious to those skilled in the art that the present invention is not limited to the details of the above exemplary embodiments, and the present invention can be implemented in other specific forms without departing from the spirit or basic features of the present invention. Therefore, no matter from which point of view, the embodiments should be regarded as exemplary and non-restrictive. The scope of the present invention is defined by the appended claims rather than the above description, and it is intended that all changes falling within the meaning and scope of the equivalent elements of the claims are included in the present invention.

Claims

1. A convex-flat conjugated three-twisted blade rotor volume pair and a helical gear power pair, characterized in that: 3-twisted blade rotor volume pair: includes two non-contact 3-twisted blade rotors with the same end face profile, opposite spiral directions and the same spiral angle; Helical gear power pair: includes two contacting standard cylindrical helical gears with the same end face profile, opposite spiral directions and the same spiral angle; The end face pitch circle radius and helical angle of the 3-twisted blade rotor volume pair and the helical gear power pair are the same. The helical direction of the 3-twisted blade rotor on the same axis is opposite to that of the standard cylindrical helical gear. The theoretical contour of the half blade end face of the 3-twisted blade rotor is composed of six parts, namely, the top concentric arc, the outer transition contour segment, the outer conjugate contour segment, the half blade pitch chord height, the inner transition contour segment and the valley concentric arc connected end to end. The corresponding endpoints and connection points are the peak point, the vertex, the outer starting point, the midpoint, the inner starting point, the root point and the valley point on the valley symmetry axis, respectively. The two boundaries are the peak symmetry axis and the valley symmetry axis, the angle between the peak symmetry axis and the valley symmetry axis is 60°, and the chord height of the nodal arc between the peak symmetry axis and the valley symmetry axis is the half-blade nodal chord height; the central angle of the nodal arc from the intersection of the normal line at the vertex of the outer transition contour segment and the nodal circle to the midnode is the vertex nodal angle β; the outer transition contour segment is a swept trajectory line of the known inner starting point of the paired rotor on the rotor; the outer conjugate contour segment is a conjugate trajectory line of the known half-blade nodal chord height on the paired rotor on the rotor; the inner transition contour segment is a swept trajectory line of the known vertex on the paired rotor on the rotor.

2. A convex-flat conjugated three-twisted blade rotor volume pair and helical gear power pair as claimed in claim 1, characterized in that: The helical angle of the three-twisted blade rotor and the standard cylindrical helical gear is 19.5° to 20.5°.

3. A convex-flat conjugated three-twisted blade rotor volume pair and helical gear power pair as claimed in claim 2, characterized in that: The twist blade staggered angle of the contours at both ends of the three-twisted blade rotor is 60°.

4. A convex-flat conjugated three-twisted blade rotor volume pair and helical gear power pair as claimed in claim 3, characterized in that: The axial staggered angles of the profiles at both ends of the standard cylindrical helical gear are determined by the number of teeth.

5. A convex-flat conjugated three-twisted blade rotor volume pair and helical gear power pair as claimed in claim 1, characterized in that: The axial staggered angle of the profile at both ends of the standard cylindrical helical gear numerically satisfies: the axial staggered angle of the profile at both ends of the standard cylindrical helical gear = 360° / number of teeth.

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