Internal gear pump for low-viscosity medium

Abstract

The utility model discloses an internal gear pump for a low-viscosity medium, which relates to the technical field of gear pumps and comprises an oil inlet pump body and an oil outlet pump body, at least two middle pump bodies are connected in series between the oil inlet pump body and the oil outlet pump body, and the middle pump bodies are used for pressurizing the low-viscosity medium. And different numbers of intermediate pump bodies are connected in series according to different viscosities of media so as to realize different pressurization stages. The utility model has the effects of being suitable for low-viscosity liquid conveying medium, meeting the pressure requirement and reducing the internal leakage amount.

Description

Technical Field

[0001] The utility model relates to the technical field of gear pumps, and more specifically, it relates to an internal gear pump for low-viscosity media. Background Art

[0002] Internal gear pumps are mostly used as power units in hydraulic systems to provide pressure for the hydraulic systems. Internal gear pumps are commonly used in industries such as petroleum, chemical, coating, dye, food, grease, and medicine. Currently, medium and low pumps are more commonly used in the market for internal gear pumps. The external shape is as Figure 1 shown, with primary pressurization and only one oil discharge pump body, and the pressure is below 14MP; the external shape of the high-pressure pump is as Figure 2 , with secondary pressurization, having an intermediate pump body and an oil discharge body, and the pressure is below 32MP. As a positive displacement mechanical pump, the gear pump adopts the principle of internal gear meshing. See Figure 3 , including rotating components: external gear, internal gear ring, shaft; stationary components: pump body; also including a suction chamber, a discharge chamber, and a crescent block. Among them, the pitch circles of the external gear and the internal gear ring are closely adjacent to one side, and the other side is separated by a crescent plate, forming three pressure regions along the circumference, namely a low-pressure region corresponding to the suction chamber, a high-pressure region corresponding to the discharge chamber, and a pressure transition region where the crescent plate is located.

[0003] There is a gap between the rotating components and the stationary components. As long as there is a gap, the liquid used as the medium for the gear pump can pass through. Therefore, the volume of the liquid sucked into the gear pump and the volume of the liquid discharged are not equal, but reduced. Because a part of the liquid leaks internally through the gap and returns to the inlet again. So, the volumetric efficiency of the gear pump (the ratio of the volume of oil discharged from the outlet when the gear rotates one circle to the volume of oil sucked into the inlet) basically cannot reach 100%, and the magnitude of the internal leakage is one of the important indicators of the pump performance. The magnitude of the flow velocity of the liquid in the gap is related to the size of the gap itself and the viscosity of the liquid. For liquids with the same viscosity, the larger the gap, the greater the flow velocity; the smaller the gap, the smaller the flow velocity. For the same gap, the greater the viscosity of the liquid, the smaller the flow velocity; the smaller the viscosity of the liquid, the greater the flow velocity. In order to make the volumetric efficiency of the pump meet the standard, since the gap is inevitable and cannot be infinitely reduced, certain requirements are put forward for the viscosity of the liquid used as the medium of the pump.

[0004] The viscosity requirement of internal gear pumps on the market for hydraulic oil is generally between 20 and 50 centistokes. At present, the No. 46 hydraulic oil provided on the market can basically meet the viscosity requirements of existing internal gear pumps. However, there are still many liquids with very low viscosities, such as brake fluid, diesel, and aviation kerosene, and some have viscosities of only a few centistokes. For low-viscosity liquids, it is very difficult to achieve the required flow rate and pressure if the current internal gear pumps are used. After testing, if a high-pressure pump is used to pump aviation kerosene, the pressure can only reach a little more than 10 MP, which is quite different from the required rated pressure, and the pressure is unstable, and the parts wear seriously in a short period. That is to say, the current high-pressure pumps are not suitable for use with low-viscosity liquids such as aviation kerosene. Therefore, how to provide an internal gear pump suitable for low-viscosity liquid transport media and capable of meeting the pressure requirements is an urgent problem to be solved at present. Summary of the Utility Model

[0005] In view of this problem in practical applications, the purpose of the present utility model is to provide an internal gear pump for low-viscosity media, which is suitable for low-viscosity liquid transport media and can also meet the pressure requirements. The specific solution is as follows:

[0006] An internal gear pump for low-viscosity media includes an inlet oil pump body and an outlet oil pump body. At least two intermediate pump bodies are connected in series between the inlet oil pump body and the outlet oil pump body. The intermediate pump bodies are used for pressurizing when facing low-viscosity media, and different numbers of intermediate pump bodies are connected in series according to the different viscosities of the media to achieve different pressurization levels.

[0007] Further, when the medium is aviation kerosene, the number of the intermediate pump bodies is four, and at this time the pressurization level is five.

[0008] Further, it also includes a shaft that sequentially passes through the inlet oil pump body, each of the series-connected intermediate pump bodies, and the outlet oil pump body.

[0009] Further, an oil drain hole is also provided along the central axis inside the shaft.

[0010] Further, the intermediate pump body has an oil suction chamber and an oil outlet chamber, and the oil outlet chamber of the intermediate pump body communicates with the oil suction chamber of the adjacent intermediate pump body.

[0011] Further, oil grooves are also provided inside the intermediate pump body and the outlet oil pump body, and the oil grooves communicate with the oil suction chambers and oil outlet chambers of every two adjacent pump bodies.

[0012] Further, the pump is heat-treated.

[0013] Further, every two adjacent intermediate pump bodies are tightly connected by bolts.

[0014] Compared with the prior art, the beneficial effects of the present utility model are as follows:

[0015] (1) Based on the secondary pump, the intermediate pump body is connected in series and superimposed in this application. Since under the same clearance and the same rotational speed, the more the number of intermediate pump bodies connected in series, the higher the pressure. Therefore, under the same pressure requirement, by superimposing the intermediate pump bodies, the pressure borne by each section of the pump is reduced to adapt to low-viscosity media and reduce the internal leakage volume;

[0016] (2) By heat-treating the pump body, the wear resistance of the pump body is improved to adapt to the pumping of low-viscosity media;

[0017] (3) By arranging oil grooves at the bottoms of the oil suction chamber and the oil discharge chamber, the volume of the chamber is increased, which can reduce the fluctuation of the output pressure and improve the stability of the output pressure. Description of the Drawings

[0018] Figure 1 is the overall schematic diagram of the medium-low pump in the prior art;

[0019] Figure 2 is the overall schematic diagram of the high-pressure pump in the prior art;

[0020] Figure 3 is the structural schematic diagram of the internal gear pump in the prior art;

[0021] Figure 4 is the structural schematic diagram of the internal gear pump in the present utility model;

[0022] Figure 5 is the internal schematic diagram of the internal gear pump in the present utility model;

[0023] Figure 6 For the present utility model Figure 5 Cross-sectional view at A-A.

[0024] Reference numerals: 1, inlet pump body; 2, discharge pump body; 3, inlet; 4, distribution disk; 5, outlet; 6, intermediate pump body; 7, shaft; 8, pump body; 9, external gear; 10, internal gear ring; 11, crescent plate; 12, oil suction chamber; 13, oil discharge chamber; 14, oil groove; 15, oil drain hole. Detailed Embodiments

[0025] Next, the technical solutions in the embodiments of the present utility model will be clearly and completely described in conjunction with the drawings in the embodiments of the present utility model. Obviously, the described embodiments are only a part of the embodiments of the present utility model, rather than all of the embodiments.

[0026] For pumps of the same structure, at the same rotational speed and pressure, as the viscosity of the medium decreases, the internal leakage will increase, that is, the volume of the output medium per unit time will become smaller. When facing low-viscosity media such as aviation kerosene, the pressure is insufficient at the same rotational speed and cannot meet the actual requirements. To meet the requirements, in this application, it is achieved by superimposing the intermediate pump body 6 on the basis of the secondary pump. By increasing the number of intermediate pump bodies 6, the pressure borne by each section of the pump is reduced to adapt to low-viscosity media and reduce internal leakage.

[0027] Specifically, as Figures 4 - 6 shown, an internal gear pump for low-viscosity media includes an inlet pump body 1 and a discharge pump body 2. An inlet port 3 is provided on the inlet pump body 1. One end of the discharge pump body 2 facing away from the intermediate pump body 6 is connected with a distribution disk 4, and an outlet port 5 is provided on the distribution disk 4. At least two intermediate pump bodies 6 are connected in series between the inlet pump body 1 and the discharge pump body 2. It also includes a shaft 7, and the shaft 7 sequentially penetrates through the inlet pump body 1, the series-connected intermediate pump bodies 6, and the discharge pump body 2. The shaft 7 is used as the active driving part in this embodiment.

[0028] Among them, both the intermediate pump body 6 and the discharge pump body 2 include a pump body 8 and a rotating part arranged in the pump body 8. The rotating part includes an external gear 9, an internal gear ring 10, and a crescent plate 11. The external gear 9 is sleeved outside the shaft 7 and is fixed relative to the shaft 7. The internal gear ring 10 is sleeved outside the external gear 9 and is meshed and connected with the external gear 9. One side of the external gear 9 is close to the pitch circle of the internal gear ring 10, and it is ensured that the central axis of the internal gear ring 10 is parallel and spaced from the central axis of the external gear 9. The other side of the external gear 9 is separated by the crescent plate 11. An oil suction chamber 12 and an oil discharge chamber 13 are formed inside the rotating part. The oil suction chamber 12 corresponds to the low-pressure area, and the oil discharge chamber 13 corresponds to the high-pressure area. The oil suction chamber 12 and the oil discharge chamber 13 are separated by the crescent plate 11, and the crescent plate 11 divides the high and low pressure areas. The area where the crescent plate 11 is located is the pressure transition area. A pair of external gear 9 and internal gear ring 10 rotate in the same direction through internal meshing, thereby conveying the medium and generating pressure.

[0029] Between the inlet pump body 1 and the adjacent intermediate pump body 6: the inlet port 3 of the inlet pump body 1 is communicated with the oil suction chamber of the adjacent intermediate pump body 6; between every two adjacent intermediate pump bodies 6: the oil discharge chamber of the previous intermediate pump body 6 corresponds to the oil suction chamber of the adjacent subsequent intermediate pump body 6; between the discharge pump body 2 and the adjacent intermediate pump body 6: the oil discharge chamber of the intermediate pump body 6 corresponds to the oil suction chamber of the discharge pump body 2. And, the oil discharge chamber of the discharge pump body 2 is communicated with the outlet port 5.

[0030] Taking the example of two intermediate pump bodies connected in series, where the two intermediate pump bodies are successively set as the first intermediate pump body and the second intermediate pump body along the liquid flow direction, the flow direction of the medium after entering the internal gear pump is described as follows: The liquid enters through the oil inlet 3 of the inlet oil pump body 1. At the inlet of the first intermediate pump body, the gears are separated from each other to form a negative pressure and suck in the liquid, that is, enter the oil suction chamber of the first intermediate pump body. The gears are continuously engaged at the outlet to squeeze and output the liquid, that is, output from the oil outlet chamber of the first intermediate pump body. Then it is sucked into the oil suction chamber of the second intermediate pump body, output from the oil outlet chamber of the second intermediate pump body, then sucked into the oil suction chamber of the discharge oil pump body 2, output from the oil outlet chamber of the discharge oil pump body 2, and finally output through the oil outlet 5.

[0031] In this application, by connecting the intermediate pump bodies in series, the pressure borne by each section of the pump is reduced to adapt to low-viscosity media and reduce the internal leakage.

[0032] In addition, it should be noted that different pressurization levels are adopted according to the different viscosities of the media to meet the requirements, that is, different levels of intermediate pump bodies 6 are stacked according to the different viscosities of the media to meet the requirements. Low-viscosity media include media with a viscosity below 10 centistokes. Generally, one section of the intermediate pump body 6 can reach 5MP. If it is necessary to reach 25MP, excluding the discharge oil pump body 2, four more sections of the intermediate pump body 6 need to be added. At this time, five-level pressurization is achieved, which can meet the requirements. This embodiment gives the structure of connecting four sections of the intermediate pump body 6 in series when the medium is aviation kerosene to meet the actual use requirements.

[0033] In addition, oil grooves 14 are also provided on the pump bodies 8 of the intermediate pump body 6 and the discharge oil pump body 2. The oil grooves 14 are arranged along the axis 7 of the pump body 8. In a single pump body 8, the oil groove 14 is located at the tail of the oil suction chamber 12 and the oil outlet chamber 13 and is connected to the oil suction chamber 12 or the oil outlet chamber 13 on the pump body; the oil grooves 14 on two adjacent pump bodies 8 are connected to the oil suction chamber 12. The setting of the oil grooves 14 can make the output pressure fluctuation smaller and improve the output pressure stability.

[0034] An oil drain hole 15 is also provided in the shaft 7 along its central axis. The liquid entering the rear cavity between the discharge oil pump body 2 and the shaft 7 can flow back through the oil drain hole 15 to improve the oil leakage situation. And, compared with the existing method of opening the oil drain hole 15 on the pump body, by opening the oil drain hole 15 on the shaft 7, there is no need to modify the intermediate pump body 6, which has no impact on the intermediate pump body 6, making the intermediate body modular and facilitating the increase or decrease of the number of intermediate pump bodies 6 according to actual needs.

[0035] Furthermore, the pump body 8 is subjected to heat treatment. Since the internal gear pump of this embodiment is applicable to low-viscosity liquid media, due to the small viscosity of the medium, friction increases. In order to improve the wear resistance of the pump body, heat treatment for increasing wear resistance is performed on the pump body. By heating and cooling the material of the pump body, its organizational structure and properties are changed. Specifically, the pump body is heated to a certain temperature to cause corresponding changes in its structure, and then rapid cooling is carried out to obtain the required hardness and strength, thereby improving its wear resistance and enhancing the durability and reliability of the pump body. The heat treatment methods include flame quenching, carburizing quenching, quenching and tempering, etc. It should be noted that the heat treatment method is an existing technology, and this application will not elaborate on it here.

[0036] The above are only the preferred embodiments of the present utility model, and the protection scope of the present utility model is not limited to the above embodiments. All technical solutions falling within the idea of the present utility model belong to the protection scope of the present utility model. It should be pointed out that for those of ordinary skill in the art in this technical field, several improvements and refinements made without departing from the principle of the present utility model should also be regarded as within the protection scope of the present utility model.

Claims

1. An internal gear pump for low-viscosity media, comprising an oil inlet pump body and an oil outlet pump body, characterized in that: At least two intermediate pump bodies are connected in series between the oil inlet pump body and the oil discharge pump body. The intermediate pump bodies are used for pressurizing low-viscosity media, and different numbers of intermediate pump bodies are connected in series according to different viscosities of the media to achieve different pressurization levels.

2. The internal gear pump for low-viscosity media according to claim 1, characterized in that: When the medium is aviation kerosene, the number of the intermediate pump bodies is four, and the number of the pressurization stages is five.

3. The internal gear pump for low-viscosity media according to claim 1, characterized in that: It also includes a shaft, which sequentially penetrates the oil inlet pump body, each intermediate pump body connected in series, and the oil discharge pump body.

4. The internal gear pump for low-viscosity media according to claim 3, characterized in that: An oil drain hole is also provided in the shaft along its central axis.

5. The internal gear pump for low-viscosity media according to claim 1, characterized in that: The intermediate pump body is provided with an oil suction cavity and an oil outlet cavity, and the oil outlet cavity of the intermediate pump body is communicated with the adjacent intermediate pump body oil suction cavity.

6. The internal gear pump for low-viscosity media according to claim 5, characterized in that: The middle pump body and the oil discharge pump body are also provided with oil grooves, and the oil grooves communicate with the oil suction chamber and the oil discharge chamber of each two adjacent pump bodies.

7. The internal gear pump for low-viscosity media according to claim 1, characterized in that: The pump is heat treated.

8. The internal gear pump for low-viscosity media according to claim 1, characterized in that: Each two adjacent intermediate pump bodies are fastened with bolts.

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