A crescent plate-gear clearance variable internal meshing gear pump capable of reducing flow pulsation

Abstract

The application relates to the technical field of gears, and provides a crescent plate-gear gap variable internal meshing gear pump capable of reducing flow pulsation, which comprises a pump body, an external gear, an internal gear and a crescent plate, the external gear and the internal gear are arranged in the pump body, the external gear and the internal gear are offset meshed, the crescent plate is arranged between the tooth top of the external gear and a tooth top circular arc surface of the internal gear, and the crescent plate is gap-fitted with the external gear and the internal gear respectively. The variable gap in the pump operation process is realized through the crescent plate radius design, the flow unevenness caused by flow pulsation, the pump internal peak pressure caused by flow backflow and the cavitation damage caused by cavitation effect are reduced under the condition that the flow change of the pump is small.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of hydraulic systems, in particular to a crescent plate-gear gap variable internal meshing gear pump capable of reducing flow pulsation. BACKGROUND

[0002] The internal meshing gear pump is an industrial equipment for conveying fluid. The conventional internal gear pump comprises a pump body, an internal gear rotating in the pump body, a pinion gear engaging with the internal gear with one less tooth than the internal gear, and front and rear pump covers. The sealing between the oil suction chamber and the oil pressure chamber is achieved by the driving tooth surface of the deepest engagement between the internal gear and the pinion gear, the abutment of the internal gear, and the sliding between the tooth top of the pinion gear and the internal gear.

[0003] At present, a crescent block assembly is generally placed in the internal meshing gear pair of the pump to compensate for the radial gap of the internal meshing gear pump. The structure of the crescent block assembly is relatively complex, and the gap between the crescent plate and the two meshing gears is usually a fixed value. This unreasonable gap design may cause reverse flow phenomenon during operation, resulting in pressure spikes in the tooth cavity at some transient moments and affecting the flow non-uniformity coefficient. Based on this, the present application is proposed. SUMMARY

[0004] An object of the present application is to provide a crescent plate-gear gap variable internal meshing gear pump capable of reducing flow pulsation, so as to solve the technical problem in the prior art that the crescent block assembly is generally placed in the internal meshing gear pair of the pump to compensate for the radial gap of the internal meshing gear pump. The structure of the crescent block assembly is relatively complex, and the gap between the crescent plate and the two meshing gears is usually a fixed value. This unreasonable gap design may cause reverse flow phenomenon during operation, resulting in pressure spikes in the tooth cavity at some transient moments and affecting the flow non-uniformity coefficient.

[0005] To achieve the above-mentioned object, the technical scheme adopted by the present application is as follows: a crescent plate-gear gap variable internal meshing gear pump capable of reducing flow pulsation, comprising a pump body, an external gear, an internal gear and a crescent plate, wherein the external gear and the internal gear are arranged in the pump body, the external gear and the internal gear are offset and engaged, the crescent plate is arranged between the tooth top of the external gear and the tooth top of the internal gear, and the crescent plate is gap-fitted with the external gear and the internal gear, respectively.

[0006] Preferably, the crescent plate has two concentric inner and outer circular arc surfaces.

[0007] Preferably, the radius of the outer circular arc surface of the crescent plate gradually decreases from the middle axis to both sides.

[0008] The radius of the inner circular arc surface of the crescent plate gradually increases from the middle axis to both sides.

[0009] Preferably, the radial clearance between the crescent plate and the internal gear is proportional to the radius of the crescent plate.

[0010] Preferably, the radial clearance between the crescent plate and the external gear is proportional to the radius of the crescent plate.

[0011] Preferably, the crescent-shaped plates are arranged symmetrically along their axes.

[0012] Preferably, the curve of the radial clearance change between the crescent plate and the internal gear is a smooth curve.

[0013] Preferably, the curve of the radial clearance change between the crescent plate and the external gear is a smooth curve.

[0014] Preferably, the pump body is symmetrically arranged along its axis.

[0015] Preferably, the pump body is provided with end caps on both sides.

[0016] The above-described technical solutions in the embodiments of the present invention have at least the following technical effects or advantages:

[0017] By adopting the above technical solution, this application achieves variable clearance during pump operation solely through the design of the crescent plate radius. While ensuring that the pump flow rate does not change significantly, it reduces the flow unevenness caused by flow pulsation, the pump internal peak pressure caused by flow backflow, and the cavitation damage caused by cavitation effect. The structure is simple and the cost is low. Attached Figure Description

[0018] To more clearly illustrate the technical solutions in the embodiments of the present invention, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0019] Figure 1 This invention relates to a crescent-plate-gear variable clearance internal gear pump for reducing flow pulsation.

[0020] Schematic diagram;

[0021] Figure 2 A schematic diagram of backflow in an internal gear pump with small clearance;

[0022] Figure 3 A schematic diagram of flow leakage in an internal gear pump with large clearance.

[0023] Figure 4 Schematic diagram of variable clearance design;

[0024] Figure 5 The result is the sensitivity of the flow non-uniformity coefficient under varying gap conditions;

[0025] Figure 6 The results show the sensitivity of flow rate under varying gaps.

[0026] Figure 7 For design renderings;

[0027] Figure 8 A comparison chart of traffic under different schemes;

[0028] Figure 9 A comparison chart of flow non-uniformity coefficients under different schemes;

[0029] The following are the labeling elements in the figure:

[0030] 1. Pump body; 2. External gear; 3. Internal gear; 4. Crescent plate. Detailed Implementation

[0031] Embodiments of the present invention are described in detail below, examples of which are illustrated in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and intended to explain the present invention, and should not be construed as limiting the present invention.

[0032] In the description of this invention, it should be understood that the terms "length", "width", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention.

[0033] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this invention, "a plurality of" means two or more, unless otherwise explicitly specified.

[0034] In this invention, unless otherwise explicitly specified and limited, the terms "installation," "connection," "linking," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0035] A variable internal gear pump with a crescent-plate-gear clearance for reducing flow pulsation includes a pump body 1, an external gear 3, an internal gear 2, and a crescent-plate 4. The external gear 3 and the internal gear 2 are disposed inside the pump body 1 and are offset meshed. The crescent-plate 4 is disposed between the tooth tip of the external gear 3 and the tooth tip arc surface of the internal gear 2. The crescent-plate 4 is symmetrically arranged along its axis and has two non-concentric arc surfaces. The radius of the crescent-plate 4 gradually decreases from the central axis to both sides. The crescent-plate 4 is clearance-fitted with the external gear 3 and the internal gear 2, respectively. The radial clearance between the crescent-plate 4 and the internal gear 2 and the external gear 3 is proportional to the radius of the crescent-plate 4. The curve of the change in radial clearance between the crescent-plate 4 and the internal gear 2 and the external gear 3 is a smooth curve.

[0036] When the pump is under load, its output end is the high-pressure end, such as... Figure 2 As shown in Figure H, the oil inlet end is the low-pressure end. Figure 2 As shown in L, when there is a small gap between the gear and the crescent plate 4, as... Figure 2 As shown, when the inner and outer gear cavities are connected to the high-pressure end, the pressure is much higher than the internal pressure of the gear cavity, causing backflow into the gear cavity. In this state, the internal pressure of the gear cavity increases sharply, leading to huge pulsations in the outlet flow, generating unbalanced forces and noise. When there is a large gap between the inner gear 2, the outer gear 3, and the crescent plate 4, as... Figure 3 As shown, when the inner and outer tooth cavities are connected to the high-pressure end, the pressure is much higher than the pressure inside the tooth cavity, causing a large leakage that affects the pump's flow rate.

[0037] Through the offset meshing of the external gear 3 and the internal gear 2, and reliable axial and radial sealing, the radius of the crescent plate 4 gradually decreases from the central axis to both sides. That is, the radius of the crescent plate 4 changes with the change of the crescent plate 4 angle, satisfying the requirement that the gap when the gear sweeps across the crescent plate changes from large to small and then back to large, and the gap change is a continuous and smooth change. During this process, its profile can be any smooth curve. At the same time, the radial gap between the crescent plate 4 and the internal gear 2 and the external gear 3 changes with the rotation of the gear. In detail, the driving gear can be selected from the internal gear 2 or the external gear 3.

[0038] Combined with illustration Figure 4Design description: O1 and O2 are the rotation centers of the inner and outer rotors, G1 and G2 are the sealing points formed by the inner and outer gears 3 and the crescent plate 4, θ1 and θ2 are the sealing angles formed by the inner and outer gears 3 and the crescent plate 4, R1 and R2 are the rotation radii of the inner and outer rotors, and L is the eccentric distance between the two rotation centers.

[0039] The sensitivity of the flow non-uniformity coefficient under varying gap conditions was obtained using computational fluid dynamics methods, such as... Figure 5 As shown, calculations indicate that the flow non-uniformity coefficient increases while the flow rate decreases as the gap increases; the sensitivity of the flow rate under varying gap conditions is obtained through computational fluid dynamics methods, such as... Figure 6 As shown, the flow rate increases when the gap decreases, while the flow non-uniformity coefficient decreases. The main reason for the increase in the flow non-uniformity coefficient is that the pressure in the load chamber is higher, which leads to backflow.

[0040] Based on the above analysis, the method for designing variable clearance is as follows:

[0041] Combination Figure 4 As shown, points A and C are taken on both sides of the crescent plate 4, and point B is taken at the position of the central axis of the crescent plate 4.

[0042] As the gears rotate from point A to point B, the gap between points G1 and G2 gradually decreases, achieving a sealing effect; from point B to point C, the gap gradually increases, increasing the pressure on the gear cavity and thus reducing backflow pressure. Therefore, the profile of the crescent plate 4 changes with the increase of the rotation angle, and the radius of the crescent plate 4 changes as shown in Formula 12:

[0043]

[0044] In the formula The inner radius of the crescent plate 4, The outer radius of the crescent plate is 4. For the internal gear, radius 22, For the external gear, the radius is 33. The radial clearance between the crescent plate 4 and the internal gear 2. The radial clearance between the crescent plate 4 and the external gear 3. and It is the interval value of the change.

[0045] The gap variation in this invention is designed to be a continuous and smooth change. The coordinates of the crescent-shaped line on the left side are shown in Equation 3, and the effect is as follows: Figure 5 and Figure 7 As shown.

[0046] 3

[0047] In the formula For the maximum design clearance, To minimize the design clearance, It has four corners of a crescent-shaped plate. Let be the angle from the midpoint B to A.

[0048] The maximum design gap between the inner and outer sides was selected based on the variable values ​​shown in Table 1. 0.5mm The gap is 0.2mm. Case 1 has a constant gap of 0.5mm; Case 2 has a constant gap of 0.1mm; Case 3 has a variable outer gap and a fixed inner gap of 0.1mm; Case 4 has a variable inner gap and a fixed outer gap of 0.1mm; Case 5 has both variable inner and outer gaps. The fixed gap remains constant, while the variable gap first decreases and then increases as the four angles of the crescent plate change.

[0049]

[0050] Table 1

[0051] The traffic results for the five schemes are as follows Figure 8 As shown, the internal meshing gear pump with variable crescent plate 4 gear clearance designed in this invention to reduce flow pulsation ensures minimal flow leakage.

[0052] The results of the flow non-uniformity of the five schemes are as follows: Figure 9 As shown, the internal gear pump with reduced flow pulsation and variable crescent plate 4-gear gap designed in this invention has the smallest flow non-uniformity coefficient among all the schemes.

[0053] In some embodiments, the pump body 1 is arranged symmetrically along its axis.

[0054] By adopting the above technical solution, since the pump body 1 and the crescent plate 4 are both symmetrically arranged according to the axis, the bidirectional output can be achieved by changing the direction of the gear through the rotation of the drive mechanism.

[0055] The above are merely preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A crescent-shaped plate (4)-gear backlash variable internal gear pump with reduced flow pulsation, characterized in that, The pump includes a pump body (1), an external gear (3), an internal gear (2), and a crescent plate (4). The external gear (3) and the internal gear (2) are disposed inside the pump body (1) and are offset meshed. The crescent plate (4) is disposed between the tooth tip of the external gear (3) and the tooth tip arc surface of the internal gear (2). The crescent plate (4) is clearance-fitted with the external gear (3) and the internal gear (2) respectively. The radius of the outer arc surface of the crescent plate (4) gradually decreases from the central axis to both sides; the crescent plate (4) is symmetrically arranged along its axis; Points A and C are taken on both sides of the crescent plate (4), and point B is taken at the central axis of the crescent plate (4). The point where the internal gear (2) and the crescent plate (4) form a seal is set as G1, and the point where the external gear (3) and the crescent plate (4) form a seal is set as G2. As points G1 and G2 follow the gear rotation from point A to point B, their gap gradually decreases; as they move from point B to point C, their gap gradually increases. The profile of the crescent plate (4) changes with the increase of the rotation angle. The radius of the crescent plate (4) changes as shown in the following formula: In the formula The inner radius of the crescent plate (4) is given. The outer radius of the crescent plate (4); The radius of the internal gear (2) is... The radius of the external gear (3) is... The radial clearance between the crescent plate (4) and the internal gear (2) is... The radial clearance between the crescent plate (4) and the external gear (3) is... and It is the interval value of the change.

2. The crescent plate (4)-gear clearance variable internal meshing gear pump for reducing flow pulsation according to claim 1, characterized in that, The crescent plate (4) has two concentric arc surfaces, one inside and one outside.

3. The crescent plate (4)-gear clearance variable internal meshing gear pump with reduced flow pulsation according to claim 1, characterized in that, The curve of the radial clearance change between the crescent plate (4) and the internal gear (2) is a smooth curve.

4. A crescent plate (4)-gear clearance variable internal meshing gear pump for reducing flow pulsation according to claim 1, characterized in that, The curve of the radial clearance change between the crescent plate (4) and the external gear (3) is a smooth curve.

5. A crescent plate (4)-gear clearance variable internal meshing gear pump for reducing flow pulsation according to claim 1, characterized in that, The pump body (1) is symmetrically arranged along its axis.

6. A crescent plate (4)-gear backlash variable internal gear pump for reducing flow pulsation according to claim 1, characterized in that, The pump body (1) is provided with end caps on both sides.

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