A fixed-point conjugated three-twisted blade volumetric rotor pair and a power helical gear pair

Abstract

The present invention discloses a fixed-point conjugated 3-twisted-blade rotor volume pair and a helical gear power pair, wherein the 3-twisted-blade rotor volume pair comprises two non-contact 3-twisted-blade rotors with the same end face profile, opposite spiral directions and the same spiral angle, and the helical gear power pair comprises two contact-type standard involute cylindrical helical gears with the same end face profile, opposite spiral directions and the same spiral angle, and the end face pitch circle radius and spiral angle of the 3-twisted-blade rotor volume pair and the helical gear power pair are equal, and the spiral directions of the 3-twisted-blade rotor and the standard involute cylindrical helical gear on the same axis are opposite. The present invention has the beneficial effects of maximizing the shape coefficient and volume utilization coefficient, smaller radial leakage rate and conjugate leakage rate, and 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 and theoretically no pulsation as a volumetric auxiliary rotor, and a coupling determination of a power auxiliary helical gear with theoretical axial force offsetting each other with the volumetric auxiliary rotor. Background Art

[0002] The rotor pump is a type of volumetric equipment 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 tooth 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 the processing difficulty of twisted blades is increased, it 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.

[0004] For ordinary rotors whose shape coefficient is completely determined by the rotor conjugate contour segment, the conjugate contour segment curve types with the maximum shape coefficient are arc and involute, and their upper limits are 1.670, 1.477, 1.368 and 1.618, 1.464, 1.366 for 2-blade, 3-blade, and 4-blade, respectively. However, the problem of what curve type the conjugate contour segment is when the ordinary rotor can obtain the maximum shape coefficient among all curve types has not been solved. 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.

[0005] 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, radial leakage and conjugate leakage can be effectively suppressed through profile improvements such as equal-gap sealing with the radial inner surface of the pump casing and multi-point sealing in the conjugate zone (similar to the multiple meshing points in gear transmission with a degree of overlap > 1).

[0006] 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

[0007] The present invention aims at the higher volumetric efficiency and the absence of theoretical flow pulsation and axial force expected by the rotor pump in the background technology, and proposes a three-twisted blade rotor with an end face profile having a maximum shape coefficient among all conjugate profile curve types, radial equal sealing clearance, multi-point sealing in the conjugate area, and a 60° twisted blade staggered angle and a helical angle of 17.5° to 18.5° for the rotor end face profile, as well as the determination of a standard involute cylindrical bevel gear with the same helical angle of 17.5° to 18.5° for the mutual offset of theoretical axial force and volume pair.

[0008] To achieve the above purpose, the technical solution of the present invention is as follows:

[0009] A fixed-point conjugated 3-twist-blade rotor volumetric pair and helical gear power pair, characterized in that: the 3-twist-blade rotor volumetric pair includes two non-contact 3-twist-blade rotors with the same end face profile, opposite spiral directions and the same spiral angle; the helical gear power pair includes two contact-type standard involute cylindrical helical gears with the same end face profile, opposite spiral directions and the same spiral angle; the end face pitch circle radius and spiral angle of the 3-twist-blade rotor volumetric pair and the helical gear power pair are equal; and the spiral direction of the 3-twist-blade rotor on the same axis is opposite to that of the standard involute cylindrical helical gear.

[0010] The helix angles of the three-twisted blade rotor and the standard involute cylindrical helical gear are between 17.5° and 18.5°. The number of teeth and the normal module of the standard involute cylindrical helical gear are first determined by the helix angle of 18°, and then the specific helix angle between 17.5° and 18.5° is determined by the equal end pitch circle radius of the three-twisted blade rotor and the standard involute cylindrical helical gear.

[0011] The twisted blade staggered angle of the contours at both ends of the three-twisted blade rotor is 60°, and the axial staggered angle of the contours at both ends of the standard involute cylindrical helical gear is 360° / number of teeth.

[0012] According to the 60° staggered blade rule of the two ends of the 3-twisted blade rotor and the helix angle ξ between 17.5° and 18.5°, the aspect ratio of the 3-twisted blade rotor is:

[0013]

[0014] The end pitch radius r is uniquely determined by the rated flow Q, rated speed n, volumetric efficiency η given by the rotor pump, the volume utilization coefficient λ, shape coefficient ε and the helix angle ξ between 17.5° and 18.5° of the three-twisted blade rotor:

[0015]

[0016] The number of teeth z and normal module m of the standard involute cylindrical helical gear n First, based on the helix angle ξ of 18°, 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

[0017] 2r(ξ)×cosξ=m n z≈2r(18°)×cos(18°) (3)

[0018] Then, the specific helix angle ξ between 17.5° and 18.5° 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 the end pitch radius r(ξ).

[0019] According to the axial staggered angle rule of 360° / number of teeth of the standard involute cylindrical helical gear and the specific helix angle ξ between 17.5° and 18.5° obtained above, the aspect ratio is given by

[0020]

[0021] 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 17.5° and 18.5°, the standard normal pressure angle 20°, the tooth top height coefficient 1, and the normal top clearance coefficient 0.25 are uniquely determined.

[0022] The theoretical contour of the half-blade end face of the three-twist blade rotor consists of four parts, namely, a top concentric arc connected end to end, an outer conjugate contour segment, an inner transition contour segment, and a valley concentric arc. The corresponding endpoints and connection points are, in sequence, a peak point, a vertex, a midpoint, a root point on the peak symmetry axis, and a valley point on the valley symmetry axis. 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°, the midline of the 60° angle is the midaxis, and the intersection of the midaxis and the pitch circle is the midpoint.

[0023] The central angle of the pitch circle arc from the intersection of the normal line at the vertex of the outer conjugate contour segment and the pitch circle to the midpoint is the vertex pitch angle β.

[0024] The outer conjugate contour segment is a conjugate trajectory line of the mid-node of the paired rotor on the rotor.

[0025] The inner transition contour segment is a sweeping trajectory of the apex of the paired rotor on the rotor.

[0026] The top concentric arc and the valley concentric arc are two arcs with the rotor center as the center, rε and r×(2-ε) as the radii, and the center angles of the two arcs are both the top sealing angle α.

[0027] The top sealing angle α, shape coefficient ε and rotor volume utilization coefficient λ are all calculated from the top pitch angle β by the following formula:

[0028]

[0029] It is uniquely determined that the relevant data under β = 45° to 60° are shown in Table 1. The shape coefficient of the three-twisted blade rotor is larger than the upper limit shape coefficient of 1.477 of the existing ordinary arc rotor with the same number of blades, and even reaches the upper limit shape coefficient effect of 1.67 of the two-blade rotor, which is the maximum shape coefficient among all conjugate profile curve types.

[0030] Table 1 Top sealing angle, shape coefficient and volume utilization coefficient at top section angles of 45° to 60°

[0031]

[0032] The three-twisted blade rotor volume pair will have a total of 5 sealing points in the interval [0, α), namely "2 conjugate points + 2 vertices + 1 concentric arc", a total of 3 sealing points in the interval (α, β-30°), namely "2 conjugate points + 1 vertex", and a sealing point of "1 conjugate point" in the interval (β-30°, 30°). Compared with an ordinary rotor with only one sealing point throughout the entire process, the present invention achieves a minimized convex-flat conjugate leakage rate. In addition, due to the radial equal gap seal of the entire blade 2α top sealing angle, the present invention achieves a minimized radial leakage rate.

[0033] Compared with the prior art, the present invention has the following beneficial effects:

[0034] The fixed-point conjugated three-twisted-blade volumetric rotor pair and the power helical gear pair of the present invention have the beneficial effects of maximized shape coefficient and volume utilization coefficient, smaller radial leakage rate and conjugate leakage rate, and no theoretical flow pulsation and axial force. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] 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.

[0036] Figure 1 It is a coaxial schematic diagram of a 3-twisted blade positive displacement rotor pair and a power helical gear pair.

[0037] Figure 2 Schematic diagram of the half-blade profile structure of a 3-twisted blade rotor.

[0038] Figure 3 Schematic diagram of the identification of the number of sealing points in different intervals.

[0039] Among them: O, rotor center, O', paired rotor center, 0, peak point, 1, vertex, 2, midpoint, 3, root point, 4, valley point, O0, peak symmetry axis, O2, midaxis, O4, valley symmetry axis, 01, top concentric arc, 12, outer conjugate contour segment, 23, inner transition contour segment, 34, valley concentric arc, r, end face pitch circle radius, ε, shape coefficient, α, top sealing angle, β, top pitch angle, 5, rotor volume pair, 6, helical gear power pair, 7, driving shaft, 8, driven shaft. DETAILED DESCRIPTION

[0040] 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.

[0041] like Figures 1 to 3 As shown, a fixed-point conjugated 3-twisted-blade volumetric rotor pair and a power helical gear pair, the twisted-blade rotor volumetric pair includes two non-contact 3-twisted-blade rotors with the same end face profile, opposite spiral directions, and the same spiral angle between 17.5° and 18.5°, and the twisted blade staggered angle of the profiles at both ends of the rotor is 60°, the helical gear power pair includes two contacting standard involute cylindrical helical gears with the same end face profile, opposite spiral directions, and the same spiral angle between 17.5° and 18.5°, and the axial staggered angle of the profiles at both ends of the standard involute cylindrical helical gears is 360° / number of teeth, the end face pitch circle radius and spiral angle of the twisted-blade rotor volumetric pair and the helical gear power pair are equal, and the spiral direction of the coaxial twisted-blade rotor and the standard involute cylindrical helical gear is opposite.

[0042] The theoretical contour of the half-leaf end face of the three-twisted-blade volumetric rotor is composed of four parts, namely, a top concentric arc 01, an outer conjugate contour segment 12, an inner transition contour segment 23 and a valley concentric arc 34, which are connected end to end. The corresponding endpoints and connection points are, in sequence, a peak point 0 located on the peak symmetry axis O0, a vertex 1, a midpoint 2, a root point 3 and a valley point 4 located on the valley symmetry axis O4. The two boundaries of the half-leaf contour are the peak symmetry axis O0 and the valley symmetry axis O4, the angle between the peak symmetry axis O0 and the valley symmetry axis O4 is 60°, the midline of the 60° angle is the midaxis O2, and the intersection of the midaxis O2 and the pitch circle is the midpoint 2; the central angle of the pitch circle arc from the intersection of the normal at the vertex of the outer conjugate contour segment 12 and the pitch circle to the midpoint 2 is the top pitch angle β; the outer conjugate contour segment 12 is the conjugate trajectory of the midpoint 2 of the paired rotor on the rotor; and the inner transition contour segment 23 is the sweep trajectory of the vertex 1 of the paired rotor on the rotor.

[0043] Example: Rated flow rate 10 10 mm 3 / min, rated speed of 500 rpm, volumetric efficiency of 85%, and top node angle β = 55.9°, shape coefficient ε = 1.66, top sealing angle α = 4°, volume utilization coefficient λ = 0.60 in Table 1, then the shape coefficient of the 3-twisted blade volumetric rotor is much larger than the 1.477 upper limiting shape coefficient of the existing ordinary circular arc rotor with the same number of blades, so the present invention achieves a maximized shape coefficient.

[0044] The number of teeth z and normal module m of the standard involute cylindrical helical gear n First, based on the helix angle ξ of 18°, 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, the gear design method is based on "GB / T1357-2008 Module of cylindrical gears for general machinery and heavy machinery" and "GB1356-88 Basic tooth profile of involute cylindrical gears", and combined with the following formula:

[0045]

[0046] The approximate equality of n =4, z = 113, and then the specific value of the helix angle ξ = 17.99° between 17.5° and 18.5° is determined by the equal end face pitch radius of the rotor and the standard involute cylindrical helical gear. Finally, the corresponding specific aspect ratio φ is determined by equations (1), (2), and (4) rotor (ξ)=1.612、end face pitch radius r(ξ)=237.62mm、end face overlap ε t =1.72 and the width-to-diameter ratio of the standard involute cylindrical helical gear φ gear (ξ)=0.147.

[0047] The top concentric arc 01 and the valley concentric arc 34 are two arcs with the rotor center O as the center, rε=237.62×1.66=394.45mm and r(2-ε)=237.62×(2-1.66)=80.79mm as the radius, and the central angle is α=4°; the three-twisted blade rotor volume pair will have "2 midpoints + 2 vertices + concentric arcs" in the interval [0, 4°) for a total of 5 sealing points, in ( In the interval of (4°, 25.9°), there are "2 mid-nodes + 1 vertex", a total of 3 sealing points, and in the interval of (25.9°, 30°), there is a sealing point of "1 mid-node". Compared with the ordinary rotor with only 1 sealing point in the whole process, the multi-point sealing interval ratio reaches 86.4%. For this reason, the present invention achieves a minimized conjugate leakage rate. In addition, the radial equal-gap sealing of the whole blade with a top sealing angle of 2α=8°, for this reason, the present invention achieves a minimized radial leakage rate.

[0048] 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 fixed-point conjugated three-twisted blade rotor volume pair and helical gear power pair, characterized in that: The three-twisted blade rotor volume pair includes two non-contact three-twisted blade rotors with the same end face profile, opposite spiral directions and the same spiral angle. The helical gear power pair includes two contact-type standard involute cylindrical helical gears with the same end face profile, opposite spiral directions and the same spiral angle. The end face pitch circle radius and spiral angle of the three-twisted blade rotor volume pair and the helical gear power pair are equal. The spiral direction of the three-twisted blade rotor on the same axis is opposite to that of the standard involute cylindrical helical gear. The theoretical profile of the half blade end face of the three-twisted blade rotor is composed of the top same gears connected end to end. The invention is composed of four parts, namely, a center arc, an outer conjugate contour segment, an inner transition contour segment and a valley concentric arc. The corresponding endpoints and connection points are, in sequence, a peak point, a vertex, a midpoint, a root point on the peak symmetry axis and a valley point on the valley symmetry axis. The two boundaries of the half-leaf 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°. The median of the 60° angle is the median axis. The intersection of the median axis and the pitch circle is the midpoint. The helix angle of the three-twisted blade rotor and the standard involute cylindrical bevel gear is 17.5° to 18.5°.

2. A fixed-point conjugated three-twisted blade rotor volume pair and helical gear power pair as claimed in claim 1, characterized in that: The twist blade staggered angle of the contours at both ends of the three-twisted blade rotor is 60°.

3. A fixed-point 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 profiles at both ends of the standard involute cylindrical helical gear is 360° / number of teeth.

4. A fixed-point conjugated three-twisted blade rotor volume pair and helical gear power pair as claimed in claim 1, characterized in that: The outer conjugate contour segment is the conjugate trajectory line of the mid-node of the paired rotor on the rotor, and the central angle of the pitch circle arc from the intersection of the normal line at the vertex of the outer conjugate contour segment and the pitch circle to the mid-node is the top pitch angle.

5. A fixed-point conjugated three-twisted blade rotor volume pair and helical gear power pair as claimed in claim 1, characterized in that: The inner transition contour segment is a sweeping trajectory of the apex of the paired rotor on the rotor.

6. A fixed-point conjugated three-twisted blade rotor volume pair and helical gear power pair as claimed in claim 1, characterized in that: The top concentric arc and the valley concentric arc are two arcs with the rotor center as the center, rε and r×(2-ε) as the radii, and the central angles are both the top sealing angles, r is the end face pitch circle radius, and ε is the shape coefficient.

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