A novel gear rotor of a non-trapped liquid gear pump and its design method

Abstract

The present invention discloses a novel non-liquid-trapped gear pump rotor, which is composed of a pair of mutually meshing left gear rotors (1) and right gear rotors (2); the gear rotors include 6 to 12 teeth; the left end surface profile (101) is composed of 4 curves: 1 elliptical arc, 1 elliptical arc envelope, 1 transition curve and 1 conjugate curve; the right end surface profile (201) is composed of 4 curves: 1 elliptical arc, 1 elliptical arc envelope, 1 transition curve and 1 conjugate curve. The novel non-liquid-trapped gear pump rotor has high volumetric efficiency, simple composition profile, and is easy to optimize the design. The left gear rotor (1) and the right gear rotor (2) can achieve completely correct meshing. During operation, the leakage of fluid from the high-pressure chamber to the low-pressure chamber can be effectively reduced, and the closed volume reduction process does not occur. The volumetric efficiency is high and there is no liquid trapping phenomenon.

Description

Technical Field

[0001] The invention relates to a positive displacement rotary pump, in particular to a gear rotor of a novel non-trapped liquid gear pump and a design method thereof. Background Art

[0002] A gear rotor of a gear pump mainly comprises a left gear rotor (1) and a right gear rotor (2). The working principle is that the left gear rotor (1) and the right gear rotor (2) are two gear rotors meshing with each other. During the operation of the gear pump, the gear rotors rotate at a high speed, and liquid is continuously sucked in and discharged. The gear pump has the characteristics of simple structure, small size, simple manufacturing and reliable operation. It is mainly used in hydraulic systems, engineering machinery and petroleum industries.

[0003] The meshing gear rotors of a gear pump have a great influence on its working performance. A Chinese patent (Li Yulong, Sun Fuchun, Tang Mao. An external meshing gear pump with an involute unloading groove [P]. CN103437996A, 2013-12-11.) proposes an external meshing gear pump with an involute unloading groove. The unloading groove of the gear pump has a theoretical limit value of the unloading area, which can greatly reduce the peak value of the trapped oil pressure and alleviate the oil trapped phenomenon. However, due to the existence of the unloading groove, the gear pump structure is more complicated, which is not conducive to processing and manufacturing. At the same time, the end face seal of the gear is weakened, causing the end face leakage to increase, and reducing the volumetric efficiency of the gear pump. A Chinese patent (Cha Qian, Charlie, Deng Qian, and Cha Shiliang. A double arc gear [P]. Guangdong: CN108953554A, 2018-12-07.) proposes a double arc gear, in which the convex arc is connected to the concave arc by a straight line segment, thereby improving the load-bearing capacity and transmission efficiency. However, when the straight line segment connects the convex arc and the concave arc, there is an uneven connection point, the profile of the gear rotor is not fully engaged, and there is a liquid trapped phenomenon.

[0004] The gear rotors of existing gear pumps have the following problems: the profiles of the gear rotors are not completely meshed, the volumetric efficiency is low, and there is a phenomenon of liquid entrapment. Summary of the invention

[0005] In view of the problems of incomplete meshing of the above gear rotor profiles, low volumetric efficiency and liquid trapping, the present invention proposes a novel gear rotor for a gear pump without liquid trapping, designs a new end face profile of the gear rotor, which is composed of an elliptical arc, an elliptical arc envelope, a transition curve and a conjugate curve, and provides design methods for the four curves; the left conjugate curve AE, the left elliptical arc AB, the left transition curve BC, and the left elliptical arc envelope CD, each section of adjacent curves is smoothly connected; the right transition curve ea, the right elliptical arc envelope ab, the right conjugate curve bc, and the right elliptical arc cd, each section of adjacent curves is smoothly connected; the novel external meshing gear pump rotor without liquid trapping proposed by the present invention has a simple profile, is easy to optimize the design, does not produce a closed volume reduction process during operation, has high volumetric efficiency, and is free of liquid trapping, enriches the gear pump rotor profile types, and is of great significance to promoting the development of gear pumps.

[0006] The technical solution adopted by the present invention to solve its technical problem is:

[0007] A novel gear rotor of a non-trapped liquid gear pump comprises a left gear rotor and a right gear rotor; the left end face profile of the left gear rotor comprises 6 to 12 teeth, and the profile of each tooth is composed of four smoothly connected curves, which are: a left conjugate curve AE, a left elliptical arc AB, a left transition curve BC, and a left elliptical arc envelope CD; the left end face profile of the left gear rotor is composed of the above four curves connected smoothly from beginning to end, which is completely smooth and centrally symmetrical;

[0008] The right end face profile of the right gear rotor includes 6 to 12 teeth, and the profile of each tooth is composed of 4 smoothly connected curves, which are: right transition curve ea, right elliptical arc envelope ab, right conjugate curve bc, and right elliptical arc cd; the right end face profile of the right gear rotor is composed of the above 4 curves connected smoothly from beginning to end, which is completely smooth and centrally symmetrical;

[0009] The left end face profile of the left gear rotor is mirror-symmetrical to the right end face profile of the right gear rotor;

[0010] The left conjugate curve AE, the left elliptical arc AB, the left transition curve BC, and the left elliptical arc envelope CD on the left end surface profile of the left gear rotor can respectively achieve correct meshing with the right transition curve ea, the right elliptical arc envelope ab, the right conjugate curve bc, and the right elliptical arc cd on the right end surface profile of the right gear rotor;

[0011] The center points O1 and O2 of the left elliptical arc AB and the left elliptical arc envelope CD of the left end face profile of the left gear rotor are both on the pitch circle of the left gear rotor, the pitch circle radius is R2, and the center angles of the left elliptical arc AB and the left elliptical arc envelope CD are the same, both 2θ, and the value range is Where z is the number of teeth.

[0012] A design method for a gear rotor of a novel non-trapped liquid gear pump is characterized by comprising the following steps:

[0013] 1) Determine the number of teeth z; determine the radius of the tooth tip circle R1; determine the radius of the tooth root circle R3; the central angle 2θ between the left elliptical arc AB and the left elliptical arc envelope CD; obtain the pitch circle radius

[0014] A coordinate system is established with the rotation center O of the left gear rotor (1) as the origin, and a tooth top circle with a radius of R1, a pitch circle with a radius of R2, and a tooth root circle with a radius of R3 are drawn respectively;

[0015] 2) Determine the rectangular coordinate equations of various component curves of the left end surface profile (101) of the left gear rotor (1):

[0016] ① Determine the left elliptical arc AB according to the following equation:

[0017]

[0018] Where y AB is the dependent variable, x is the independent variable, a is the major semi-axis of the ellipse, b is the minor semi-axis of the ellipse, where 5 <b<a<12;

[0019] ② Determine the left elliptical arc envelope CD by following the steps below:

[0020] The parametric equation of the left elliptical arc AB is:

[0021]

[0022] Determine the corner

[0023]

[0024] Get the coordinate transformation matrix M

[0025]

[0026] The equation of the left elliptical arc envelope CD is:

[0027]

[0028] Where y CD is the dependent variable and x is the independent variable;

[0029] ③ Determine the left transition curve BC according to the following equation:

[0030]

[0031] Where yBC is the dependent variable, x is the independent variable, where a0, a1, a2, and a3 are constants determined by the following set of equations:

[0032] ④ Determine the left conjugate curve AE according to the following steps

[0033] The left transition curve BC is expressed as a parametric equation:

[0034]

[0035] Get the corner

[0036]

[0037] Get the coordinate transformation matrix M

[0038]

[0039] The equation of the left conjugate curve AE is:

[0040]

[0041] 3) The left conjugate curve AE, the left elliptical arc AB, the left transition curve BC, and the left elliptical arc envelope CD are arranged in z circular arrays with the rotation center O as the center to obtain the left end surface profile of the left gear rotor;

[0042] 4) Mirror the left end face profile of the left gear rotor to obtain the right end face profile of the right gear rotor;

[0043] 5) According to the left end face profile and the right end face profile, the left gear rotor and the right gear rotor are respectively generated by scanning along the spiral line, wherein the spiral angle β ranges from 10° to 30°;

[0044] Above: z—number of teeth; a—major semi-axis of the ellipse, mm; b—minor semi-axis of the ellipse, mm; R1—radius of the tooth top circle, mm; R2—radius of the pitch circle, mm; R3—radius of the tooth root circle, mm; θ—half of the central angle subtended by the elliptical arc and its envelope, rad.

[0045] A gear pump uses the left gear rotor and the right gear rotor.

[0046] The beneficial effects of the present invention are:

[0047] ① The gear rotor of the proposed new type of liquid-free gear pump has no liquid-trapped phenomenon during operation, has high volumetric efficiency, and does not produce a closed volume reduction process.

[0048] ② The gear rotors of the proposed new type of non-trapped liquid gear pump, the left gear rotor (1) and the right gear rotor (2) can achieve completely correct meshing, and during the working process, can effectively reduce the leakage of fluid from the high-pressure chamber to the low-pressure chamber.

[0049] ③ The gear rotor of the proposed new type of liquid-free gear pump has a simple profile and is easy to optimize the design. BRIEF DESCRIPTION OF THE DRAWINGS

[0050] Figure 1 The left end profile (101) of the left gear rotor (1) is shown.

[0051] Figure 2 It is a right end surface profile (201) diagram of the right gear rotor (2).

[0052] Figure 3 It is a meshing diagram of the left end face profile (101) and the right end face profile (201).

[0053] Figure 4 FIG. 2 is a meshing diagram of the left gear rotor (1) and the right gear rotor (2).

[0054] In the figure: 1—left gear rotor (1); 2—right gear rotor (2); 101—left end face profile (101); 201—right end face profile (201); a—long semi-axis of the ellipse, mm; b—short semi-axis of the ellipse, mm; R1—tooth tip circle radius, mm; R2—pitch circle radius, mm; R3—tooth root circle radius, mm; θ—half of the central angle subtended by the elliptical arc and its envelope, rad. DETAILED DESCRIPTION

[0055] The present invention will be further described below in conjunction with the accompanying drawings.

[0056] like Figure 1 As shown, the left end profile 101 of the left gear rotor 1 is formed by connecting four curves, namely: left conjugate curve AE, left elliptical arc AB, left transition curve BC, and left elliptical arc envelope CD. The left end profile 101 is formed by connecting the above four curves in sequence, which is completely smooth and centrally symmetrical. The design method of the left end profile 101 is as follows:

[0057] 1) Determine the number of teeth z; determine the radius of the tooth tip circle R1; determine the radius of the tooth root circle R3; the central angle 2θ between the left elliptical arc AB and the left elliptical arc envelope CD; obtain the pitch circle radius

[0058] A coordinate system is established with the rotation center O of the left gear rotor (1) as the origin, and a tooth top circle with a radius of R1, a pitch circle with a radius of R2, and a tooth root circle with a radius of R3 are drawn respectively;

[0059] 2) The rectangular coordinate equations of the various component curves of the left end surface profile 101 of the left gear rotor 1 are:

[0060] ① Determine the left elliptical arc AB according to the following equation:

[0061]

[0062] Where y AB is the dependent variable, x is the independent variable, a is the major semi-axis of the ellipse, b is the minor semi-axis of the ellipse, where 5 <b<a<12;

[0063] ② Determine the left elliptical arc envelope CD by following the steps below:

[0064] The parametric equation of the left elliptical arc AB is:

[0065]

[0066] Determine the corner

[0067]

[0068] Get the coordinate transformation matrix M

[0069]

[0070] The equation of the left elliptical arc envelope CD is:

[0071]

[0072] Where y CD is the dependent variable and x is the independent variable;

[0073] ③ Determine the left transition curve BC according to the following equation:

[0074] y BC =a3x 3 +a2x 2 +a1x+a0, Where y BC is the dependent variable, x is the independent variable, where a0, a1, a2, and a3 are constants determined by the following set of equations:

[0075] ④ Determine the left conjugate curve AE according to the following steps

[0076] The left transition curve BC is expressed as a parametric equation:

[0077]

[0078] Get the corner

[0079]

[0080] Get the coordinate transformation matrix M

[0081]

[0082] The equation of the left conjugate curve AE is:

[0083]

[0084] 3) The left conjugate curve AE, the left elliptical arc AB, the left transition curve BC, and the left elliptical arc envelope CD are arranged into z circular arrays with the rotation center O as the center to obtain the left end surface profile 101 of the left gear rotor 1;

[0085] like Figure 2 As shown, the right end face profile 201 of the right gear rotor 2 is formed by connecting four curves, namely: right transition curve ea, right elliptical arc envelope ab, right conjugate curve bc, and right elliptical arc cd. The right end face profile 201 is formed by connecting the above four curves in sequence, which is completely smooth and centrally symmetrical. The right end face profile 201 is mirror-symmetrical with the left end face profile 101, and the design method is the same.

[0086] like Figure 3 As shown, it is the meshing diagram of the left end face profile 101 and the right end face profile 201. The left end face profile 101 and the right end face profile 201 are mirror-symmetrical. The left conjugate curve AE, the left elliptical arc AB, the left transition curve BC, and the left elliptical arc envelope CD on the left end face profile 101 can respectively achieve correct meshing with the right transition curve ea, the right elliptical arc envelope ab, the right conjugate curve bc, and the right elliptical arc cd on the right end face profile 201.

[0087] like Figure 4 As shown, it is a meshing diagram of the left gear rotor 1 and the right gear rotor 2. According to the left end face profile 101 and the right end face profile 201, the left gear rotor 1 and the right gear rotor 2 are respectively generated by scanning the helical line on the pitch circle along the normal tooth profile, wherein the pitch circle helical angle β ranges from 10° to 30°, and the left gear rotor 1 and the right gear rotor 2 are completely and correctly meshed.

[0088] Although the above describes the specific implementation mode of the present invention in conjunction with the accompanying drawings, it is not intended to limit the scope of protection of the present invention. Those skilled in the art should understand that various modifications or variations that can be made by those skilled in the art on the basis of the technical solution of the present invention without creative work are still within the scope of protection of the present invention.

Claims

1. A design method for a new type of gear rotor of a non-trapped liquid gear pump, comprising: A left gear rotor (1) and a right gear rotor (2); the characteristics are: the left end face profile (101) of the left gear rotor (1) includes 6 to 12 teeth, and the profile of each tooth is composed of four curves connected smoothly, which are: a left conjugate curve AE, a left elliptical arc AB, a left transition curve BC, and a left elliptical arc envelope CD; the left end face profile (101) of the left gear rotor (1) is composed of the above four curves connected smoothly in sequence from beginning to end, is completely smooth, and is centrally symmetrical; The right end surface profile (201) of the right gear rotor (2) includes 6 to 12 teeth, and the profile of each tooth is composed of four smoothly connected curves, which are: a right transition curve ea, a right elliptical arc envelope ab, a right conjugate curve bc, and a right elliptical arc cd. The right end surface profile (201) of the right gear rotor (2) is composed of the above four curves connected smoothly in sequence from beginning to end, and is completely smooth and centrally symmetrical. The left end surface profile (101) of the left gear rotor (1) and the right end surface profile (201) of the right gear rotor (2) are mirror-symmetrical; The left conjugate curve AE, the left elliptical arc AB, the left transition curve BC, and the left elliptical arc envelope CD on the left end surface profile (101) of the left gear rotor (1) can respectively achieve correct meshing with the right transition curve ea, the right elliptical arc envelope ab, the right conjugate curve bc, and the right elliptical arc cd on the right end surface profile (201) of the right gear rotor (2); The center points O1 and O2 of the left elliptical arc AB and the left elliptical arc envelope line CD of the left end surface profile line (101) of the left gear rotor (1) are both on the pitch circle of the left gear rotor (1), the pitch circle radius is R2, and the center angles of the left elliptical arc AB and the left elliptical arc envelope line CD are the same, both 2θ, and the value range is Where z is the number of teeth; A design method for a new type of gear rotor of a non-trapped liquid gear pump comprises the following steps: 1) Determine the number of teeth z; determine the radius of the tooth tip circle R1; determine the radius of the tooth root circle R3; the central angle 2θ between the left elliptical arc AB and the left elliptical arc envelope CD; obtain the pitch circle radius A coordinate system is established with the rotation center O of the left gear rotor (1) as the origin, and a tooth top circle with a radius of R1, a pitch circle with a radius of R2, and a tooth root circle with a radius of R3 are drawn respectively; 2) Determine the rectangular coordinate equations of various component curves of the left end surface profile (101) of the left gear rotor (1): ① Determine the left elliptical arc AB according to the following equation: Where y AB is the dependent variable, x is the independent variable, a is the major semi-axis of the ellipse, b is the minor semi-axis of the ellipse, where 5 <b<a<12; ② Determine the left elliptical arc envelope CD by following the steps below: The parametric equation of the left elliptical arc AB is: Determine the corner Get the coordinate transformation matrix M The equation of the left elliptical arc envelope CD is: Where y CD is the dependent variable and x is the independent variable; ③ Determine the left transition curve BC according to the following equation: Where y BC is the dependent variable, x is the independent variable, where a0, a1, a2, and a3 are constants determined by the following system of equations: ④ Determine the left conjugate curve AE according to the following steps The left transition curve BC is expressed as a parametric equation: Get the corner Get the coordinate transformation matrix M The equation of the left conjugate curve AE is: 3) Arranging the left conjugate curve AE, the left elliptical arc AB, the left transition curve BC, and the left elliptical arc envelope CD into z circular arrays with the rotation center O as the center, thereby obtaining the left end surface profile (101) of the left gear rotor (1); 4) The left end surface profile line (101) of the left gear rotor (1) is mirror-symmetrically obtained to obtain the right end surface profile line (201) of the right gear rotor (2); 5) According to the left end surface profile line (101) and the right end surface profile line (201), a left gear rotor (1) and a right gear rotor (2) are respectively generated by scanning along the helical line, wherein the helical angle β is in the range of 10° to 30°; Above: z—number of teeth; a—major semi-axis of the ellipse, mm; b—minor semi-axis of the ellipse, mm; R1—radius of the tooth top circle, mm; R2—radius of the pitch circle, mm; R3—radius of the tooth root circle, mm; θ—half of the central angle subtended by the elliptical arc and its envelope, rad.

2. A gear pump, characterized in that: The left gear rotor (1) and the right gear rotor (2) described in claim 1 are used.

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