Pressure balance structure type screw pump

Abstract

The invention provides a pressure balance structure type screw pump, and belongs to the technical field of screw pumps. The pressure balance structure type screw pump comprises a pump body, a driving screw arranged in the pump body and a driven screw matched with the driving screw, and further comprises a limiting assembly and a pressure balance assembly, the limiting step is arranged on the rod wall, located in the pump outlet cavity, of the main screw and connected with the rod end of the auxiliary screw, the limiting piece is arranged at the rod end, located in the pump inlet cavity, of the auxiliary screw and used for positioning the auxiliary screw, and at least part of the end face of the limiting step makes contact with and is attached to the rod end of the auxiliary screw. The limiting step is of a circular ring structure arranged along the rod wall of the main screw rod. According to the screw pump, by arranging the limiting assembly and adding the structure that the driving screw and the driven screw are attached, axial movement caused by unbalanced pressure is eliminated, and then the operation stability of the driving screw and the driven screw is improved, so that abrasion is reduced, the service life of the screw pump is prolonged, and the operation stability is enhanced.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of screw pump, in particular to a pressure balance structure type screw pump. BACKGROUND

[0002] The screw pump is a kind of positive displacement rotor pump, its core feature is to use one or more intermeshing screw to rotate in the pump shell, and to transport liquid by the axial movement of the closed cavity formed, which has the characteristics of stable, low pulsation, high efficiency, and the ability to transport high viscosity or solid particle containing medium. Medium and high pressure screw pump generally refers to the screw pump with pressure reaching 5mpa-10mpa, and the medium low viscosity (generally less than 20cst) medium and high pressure screw pump has been slowly popularized in China. In many industries, such as military industry, power industry, ship industry and other industries, there is a great demand for medium low viscosity medium and high pressure pump.

[0003] Although the market demand is large, there is still a bottleneck in use, that is, under complex working conditions, the screw pair wears quickly, and once the wear increases, the performance parameters such as flow and pressure of the pump cannot be met. In view of this problem, the mainstream improvement scheme of the prior art is to set a single high pressure balance structure in the pump body, specifically, a limiting sleeve is arranged at the rear end of the screw, and the positioning of the screw is realized through the limiting sleeve. However, this single high pressure balance structure has great instability, that is, it requires high working condition and machining precision, and needs to be precisely positioned from the rear end of the screw, which increases the difficulty of machining and assembly, and the cost is also high. It is easy to cause unstable operation of the screw during work, which leads to increased wear and causes the performance parameters such as flow and pressure of the pump body to be unable to meet the actual use demand. SUMMARY

[0004] The present application provides a pressure balance structure type screw pump, by setting a limiting assembly, increasing the structure of the main screw and the slave screw, resolving the axial movement caused by the unbalanced pressure, and then improving the stability of the operation of the two, to reduce the wear, improve the service life of the screw pump, and enhance the stability of the operation.

[0005] A pressure balance structure type screw pump, comprising a pump body, a main screw arranged in the pump body, and a slave screw cooperating with the main screw, further comprising:

[0006] A limiting assembly, the limiting assembly comprises a limiting step arranged on the rod wall of the main screw in the pump outlet cavity and engaged with the rod end of the slave screw, and a limiting sheet arranged on the rod end of the slave screw in the pump inlet cavity and used for positioning the slave screw.

[0007] Preferably, at least part of the end surface of the limiting step is in contact with the rod end of the slave screw.

[0008] Preferably, the limiting step is a circular ring structure arranged along the rod wall of the main screw.

[0009] Preferably, the end of the slave screw located in the pump outlet cavity is provided with an engaging step in contact with the inner side end face of the limiting step.

[0010] Preferably, the engaging surface of the limiting step and the engaging step at least partially covers the inner side end face of the limiting step.

[0011] Preferably, the end of the slave screw is further provided with a limiting column, the side surface of the limiting column forms a line contact with the side surface of the limiting step, and the length of the line contact distributed along the axial direction of the main screw is less than or equal to the axial length of the limiting step.

[0012] Preferably, the end face of the limiting step and the limiting column close to the side of the pump outlet cavity is in the same plane.

[0013] Preferably, the limiting piece is a piece-shaped square structure fixed on the end of the slave screw.

[0014] Preferably, the limiting piece is made of ceramic material.

[0015] Preferably, the pressure balance structure type screw pump further comprises a pump cover, and the limiting piece is arranged on the inner side of the pump cover away from the end of the slave screw.

[0016] Preferably, the end of the pump cover is provided with a boss corresponding to the limiting piece, and the boss is fixedly connected with the limiting piece through a fastener.

[0017] Preferably, the boss is in a semi-elliptical shape.

[0018] Preferably, the slave screw is axially provided with a through liquid hole penetrating the whole rod.

[0019] From the above technical solutions, the present application has the following beneficial effects: 1. In the present application, the limiting step and the limiting piece are arranged on both sides of the pump outlet cavity and the pump inlet cavity to realize the positioning of the main screw and the slave screw, specifically, the limiting step can abut and fit the one side rod end of the slave screw to achieve the purpose of axial positioning from one side, at the same time, the limiting piece can fit and fix the other side rod end of the slave screw to achieve the purpose of axial positioning from the other side, in this way, the main screw and the slave screw can form a hanging structure from the two sides of the axial direction, which can solve the axial movement caused by pressure imbalance, and further improve the stability of the operation of the two, so as to reduce the wear and tear and improve the service life of the screw pump; and one of the main screw and the slave screw can be used as the basis for processing or assembly, and then the processing or assembly of the other one is realized, compared with the single high pressure balance structure, the present application has the advantages of simple processing and assembly. BRIEF DESCRIPTION OF DRAWINGS

[0020] Figure 1 The present application provides the overall schematic diagram of the screw pump; Figure 2 is a structural schematic view of the A-A section in the middle; Figure 1 is a structural schematic view of the A-A section in the middle; Figure 3 is a structural schematic view of the B-B section in the middle; Figure 2 is a structural schematic view of the B-B section in the middle; Figure 4 is a structural schematic view of the B-B section in the middle; Figure 3 is an enlarged view of the A section in the middle; Figure 5 is a structural schematic view of the pump cover.

[0021] In the figure: 10, pump body; 110, pump outlet cavity; 120, pump inlet cavity; 20, main screw; 30, slave screw; 410, limiting step; 420, limiting piece; 430, joint step; 50, pump cover; 510, boss. DETAILED DESCRIPTION

[0022] The preferred embodiment of the present application will be described in detail below with reference to the accompanying drawings.

[0023] To achieve the above object, the embodiments of the present application adopt the following technical solutions: referring to Figure 1 , Figure 2 , Figure 3 , Figure 4A pressure-balanced screw pump includes a pump body 10, a main screw 20, and a driven screw 30. The main screw 20 is rotatably mounted inside the pump body via bearings and other components. The driven screw 30 engages with the main screw 20. Both the main screw 20 and the driven screw 30 have meshing threaded sections, so that when the main screw 20 rotates, it can synchronously drive the driven screw 30 to rotate. Furthermore, the screw pump also includes a limiting assembly, which includes a limiting step 410 and a limiting plate 420. The limiting step 410 is located on the rod wall of the main screw 20 within the pump outlet chamber 110 and engages with the rod end of the driven screw 30. The limiting plate 420 is located on the rod end of the driven screw 30 within the pump inlet chamber 120 and is used to position the end of the driven screw 30. Thus, the driven screw 30 rotates synchronously. Limiting steps 410 and limiting plates 420 are respectively provided on both sides of the outlet chamber 110 and the pump inlet chamber 120 to position the main screw and the driven screw. The limiting steps 410 and the limiting plates 420 form a main and driven screw abutment structure. Specifically, the limiting steps 410 can abut and fit against one end of the driven screw 30 to achieve axial positioning from one side. At the same time, the limiting plates 420 can fit and fix the other end of the driven screw 30 to achieve axial positioning from the other side. Therefore, it can resolve the axial movement caused by pressure imbalance, thereby improving the stability of the operation of both, reducing wear, and increasing the service life of the screw pump. Furthermore, one of the main screw and the driven screw can be used as a processing or assembly base to realize the processing or assembly of the other. Compared with a single high-pressure balance structure, it has the advantages of simple processing and assembly.

[0024] Reference Figure 2 , Figure 3 , Figure 4 As a preferred technical solution in this embodiment, at least a portion of the end face of the limiting step 410 is in contact with the rod end of the driven screw 30. That is, in this embodiment, a portion or all of the inner end face of the limiting step 410 can be in contact with the rod end of the driven screw 30. It should be noted that the contact and fit referred to in this embodiment means that the contact surfaces of the two are always in contact when they rotate with the main screw 20 and the driven screw 30. By using surface contact, the main and driven screws can be driven along their respective axial directions. When the main and driven screws rotate, the axial movement of the two is small, the operation is stable, and wear can be reduced.

[0025] Furthermore, by making contact and fit between the limiting step 410 and the end of the driven screw 30, when assembling the main screw 20 and the driven screw 30, the main screw 20 can be used as the assembly reference, and then the driven screw 30 can be assembled. That is, after the main screw 20 is assembled, the driven screw 30 can be assembled using the reference surface formed by the limiting step 410, thereby improving the accuracy and convenience of assembly.

[0026] Furthermore, the limiting step 410 is a ring structure set along the wall of the main screw 20. Specifically, in this embodiment, the limiting step 410 is a columnar ring structure, which can be an integral structure with the main screw 20, that is, formed on the outer wall of the main screw 20 by machining; or it can be a non-integral structure with the main screw 20, that is, fixed to the outer wall of the main screw 20 by key connection.

[0027] Reference Figure 3 , Figure 4 In some embodiments, a connecting step 430 is provided at the end of the driven screw 30 located in the pump outlet cavity 110. The connecting step 430 contacts the inner end face of the limiting step 410. Specifically, in this embodiment, a step structure is also formed at the rod end of the driven screw 30. The step structure can be a ring structure, and the step structure contacts and fits with the limiting step 410. In this way, when the main screw 20 and the driven screw 30 rotate relative to each other, the side contact and fit of the limiting step 410 and the connecting step 430 can be used to achieve the purpose of axial positioning of the main and driven screws from one side, so as to achieve stable operation of the main and driven screws.

[0028] Correspondingly, the mating surface of the limiting step 410 and the engaging step 430 covers part of the inner end face of the limiting step 410. It can be understood that, referring to Figure 1, since the limiting step 410 and the engaging step 430 are axially offset along the main screw 20, the outer end face of the engaging step 430 contacts the inner end face of the limiting step 410. The contact part between the two is the aforementioned mating surface. Since there is a gap during the assembly process, the aforementioned mating surface partially covers the inner end face of the limiting step 410.

[0029] Furthermore, the end of the driven screw 30 is also provided with a limiting post 440. The side of the limiting post 440 forms a line contact with the side of the limiting step 410. The length of this line contact distributed along the axial direction of the main screw 20 is less than or equal to the axial length of the limiting step 410. The purpose of this design is to ensure that at least a part of the side of the limiting step 410 is in contact with the limiting post 440 on the driven screw 30, thereby reducing the axial movement of the main and driven screws when they rotate, ensuring stable operation, and reducing wear.

[0030] It should be noted that in this embodiment, there are no restrictions on the axial length z1 of the limiting step 410 and the axial length z2 of the engaging step 430. That is, the relationship between the axial lengths of the two can be z1 > z2, z1 = z2, or z1 < z2, as long as the axial length of the side contact point of the limiting step 410 and the engaging step 430 along the main screw 20 is less than or equal to the axial length of the limiting step 410.

[0031] In some embodiments, to improve assembly accuracy and convenience, the end faces of the limiting step 410 and the limiting post 440 near the pump outlet cavity 110 are on the same plane. This makes the side faces of the limiting step 410 and the limiting post 440 near the pump outlet cavity 110 on the same reference plane, so that the main screw 20 and the slave screw 30 can be accurately assembled based on this reference plane during assembly.

[0032] In other embodiments, the limiting piece 420 is a sheet-like square structure, specifically in a semi-elliptical shape. The limiting piece 420 is arranged radially outward from the main screw 20 and fits against the end of the driven screw 30 to achieve axial positioning of the driven screw 30 from the other side. Furthermore, to improve the service life of the limiting piece 420, it is made of a highly wear-resistant material, such as ceramic. Replacing the original driven screw positioning structure with a high-hardness limiting piece 420 achieves the effect of flat-grinding the end face, ensuring stable operation of both the main and driven screws.

[0033] Reference Figure 1 , Figure 2 , Figure 3 , Figure 5 In some embodiments, the pressure-balanced screw pump further includes a pump cover 50, which is disposed at the front end of the pump body and cooperates with the pump body 10 to form a pump inlet cavity 120, and the limiting piece 420 is fixedly disposed on the inner side of the pump cover.

[0034] Furthermore, to secure the limiting piece 420, a boss 510 is provided at the end of the pump cover 50. It should be noted that the boss 510 can be integrally formed with the pump cover 50, i.e., prepared by integral casting or other methods, extending from the inside of the pump cover 50 towards the axial direction. The number of bosses 510 corresponds to the number of limiting pieces 420, and their shapes are similar. Simultaneously, to secure the limiting piece 420, the boss 510 is connected to the limiting piece 420 by fasteners. Specifically, the fasteners can be screws, bolts, etc. In this embodiment, the fastener is a screw. During use, a threaded hole is made in the boss 510, adhesive is applied to the screw, and the screw passes through the threaded hole in the boss 510 and is fixed to the limiting piece 420. The end of the limiting piece 420 away from the boss 510 is fitted with the end of the follower screw 30 to achieve axial positioning of the follower screw 30.

[0035] In addition, in order to improve the compatibility between the boss 510 and the limiting piece 420, the boss 510 in this embodiment is also semi-elliptical. The elliptical part of the semi-elliptical boss 510 corresponds to the elliptical part of the limiting piece 420, and both correspond to the end position of the screw 30. At this time, the inner side of the limiting piece 420 is a plane parallel to the end face of the screw 30, so that the flatness of the screw 30 will not be affected during assembly.

[0036] In some embodiments, the screw 30 is provided with a fluid passage hole that extends through the entire screw in the axial direction. This fluid passage hole is used to introduce high pressure from the high-pressure zone. The axial force of the screw 30 during operation is offset by hydraulic balance, thereby reducing friction on the components connected to the screw 30. This can effectively reduce power consumption and achieve energy saving.

[0037] The above-described embodiments are merely preferred embodiments of the present invention and are not intended to limit the scope of the present invention. Various modifications and improvements made by those skilled in the art to the technical solutions of the present invention without departing from the spirit of the present invention should fall within the protection scope defined by the claims of the present invention.

Claims

1. A pressure balanced structural type screw pump comprising a pump body (10), a main screw (20) provided in the pump body, and a slave screw (30) cooperating with the main screw (20), characterized in that, Also included are: A limiting component, which includes a limiting step (410) arranged on the rod wall of the main screw (20) inside the pump outlet cavity (110) and engaged with the rod end of the slave screw (30), and a limiting sheet (420) arranged on the rod end of the slave screw (30) inside the pump inlet cavity (120) and used for positioning the slave screw (30).

2. The pressure balanced structural screw pump of claim 1, wherein, At least part of the end surface of the limiting step (410) is in contact with the rod end of the slave screw (30).

3. The pressure balanced structural screw pump of claim 2, wherein, The limiting step (410) is a circular ring structure arranged along the rod wall of the main screw (20).

4. The pressure balanced structural screw pump of claim 3, wherein, The end of the slave screw (30) inside the pump outlet cavity (110) is provided with an engagement step (430) in contact with the inner end surface of the limiting step (410).

5. The pressure balanced structural screw pump of claim 4, wherein, The engagement surface of the limiting step (410) and the engagement step (430) covers part of the inner end surface of the limiting step (410).

6. The pressure balanced structural screw pump of claim 5, wherein, The end of the slave screw (30) is further provided with a limiting column (440), the side surface of which forms a line contact with the side surface of the limiting step (410), and the length of the line contact distributed along the axial direction of the main screw (20) is less than or equal to the axial length of the limiting step (410).

7. The pressure balanced structural screw pump of claim 6, wherein, The end surfaces of the limiting step (410) and the limiting column (440) near the side of the pump outlet cavity (110) are in the same plane.

8. The pressure balanced structural screw pump of any of claims 1-7, wherein, The limiting sheet (420) is a sheet-shaped square structure arranged on the end of the slave screw (30).

9. The pressure balanced structural screw pump of claim 8, wherein, The limiting sheet (420) is made of ceramic material.

10. The pressure balanced structural screw pump of claim 8, wherein, The pressure balance structure type screw pump further comprises a pump cover (50), and the limiting sheet (420) is arranged inside the pump cover (50) away from the slave screw (20).

11. The pressure balanced structural screw pump of claim 10, wherein, The end of the pump cover (50) is provided with a boss (510) corresponding to the limiting sheet (420), and the boss (510) is fixedly connected with the limiting sheet (420) through a fastener.

12. The pressure balanced structural screw pump of claim 11, wherein, The boss (510) is in a semi-elliptical shape.

13. The pressure balanced structural design screw pump of claim 1, wherein, The slave screw (30) is axially provided with a through liquid hole penetrating the whole rod.

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