Combined seal suitable for high-temperature, high-pressure and high-viscosity working conditions

Abstract

The invention relates to the field of sealing, in particular to a combined seal suitable for high-temperature, high-pressure and high-viscosity working conditions, a sealing cavity exists between a main shaft and a shell, a spiral seal is coaxially arranged on the main shaft, and the spiral seal comprises a sealing section used for sealing an opening of the sealing cavity and a guide section coaxially arranged with the sealing section; an annular gap for mounting the packing seal is formed between the guide section and the main shaft, the nitrogen seal is inserted into the annular gap, and the nitrogen seal is in sliding fit with the main shaft in the axial direction; the nitrogen seal applies elastic pressing force towards the direction of the sealing section to the packing seal under the action of the elastic piece. According to the combined seal, the pressing force of the spiral seal is dynamically adjusted, so that the combined seal can be matched with different working conditions of the melt pump, and the sealing performance is stable.

Description

Technical Field

[0001] The invention relates to the field of sealing, in particular to a combined seal suitable for high temperature, high pressure and high viscosity working conditions. Background Art

[0002] The melt pump is a positive displacement conveying device. The flow rate is strictly proportional to the speed of the pump. Its main structure is mainly composed of a pump housing, a driving gear shaft, a driven gear shaft, bearings, front and rear end plates, and packing seals. The gear tooth profiles of the two gear shafts, the pump body, and the side cover plates cooperate with each other to form the feed area, the delivery area, and the discharge area of ​​the pump. When working, the melt medium is conveyed by the change in working volume caused by the mutual engagement of the driving and driven gear shafts. When the gear shaft rotates in the specified direction, the melt enters the tooth groove of the gear shaft. As the gear shaft rotates, the melt is brought into the delivery area from both sides. The gears mesh again, causing the melt in the tooth groove to be squeezed out.

[0003] Under specific conveying conditions of high temperature (>250℃), high pressure (>25MPa), and high viscosity medium (>12000Pas), traditional packing seals are affected by harsh operating conditions such as high temperature and high pressure, and have a short service life. The sealing effect is reduced after long-term use and cannot meet the sealing requirements of the melt pump. Its sealing performance is unstable, so it needs to be solved urgently. Summary of the invention

[0004] In order to avoid and overcome the technical problems existing in the prior art, the present invention provides a combined seal suitable for high temperature, high pressure and high viscosity working conditions. The combined seal of the present invention can match the use of melt pumps in different working conditions by dynamically adjusting the pressing force of the spiral seal, and the sealing performance is stable.

[0005] To achieve the above object, the present invention provides the following technical solutions:

[0006] A combined seal suitable for high temperature, high pressure and high viscosity working conditions, wherein a sealing cavity is provided between a main shaft and a housing, a spiral seal is coaxially arranged on the main shaft, the spiral seal comprises a sealing section for closing an opening of the sealing cavity and a guide section coaxially arranged with the sealing section, an annular gap for installing a packing seal is provided between the guide section and the main shaft, a nitrogen seal is inserted into the annular gap, and the nitrogen seal and the main shaft are axially slidably matched; the nitrogen seal is acted upon by an elastic member to apply an elastic pressing force toward the sealing section to the packing seal.

[0007] As a further solution of the present invention: a first positioning ring is radially arranged on the guide section, a second positioning ring is radially arranged on the nitrogen seal and is arranged in parallel with the first positioning ring, and there is a spacing between the first positioning ring and the second positioning ring; the elastic member includes a spring seat coaxially arranged on the outer ring of the guide section and slidingly matched with the guide section, a guide column arranged parallel to the main shaft axis is fixed on the second positioning ring, the guide column passes through the second positioning ring and the first positioning ring in sequence and is fixedly connected to the spring seat, the clamping spring is coaxially fixed on the guide column, the two ends of the clamping spring are respectively abutted against the first positioning ring and the spring seat, and the nitrogen seal is clamped and fixed by the locking nut on the guide column.

[0008] As a further solution of the present invention: the packing seal includes at least two groups of packings, and a liquid sealing ring is arranged between two adjacent groups of packings.

[0009] As a further solution of the present invention: a water cooling jacket is coaxially arranged on the outer ring of the sealing section, and a sealing ring is arranged on the contact surface between the water cooling jacket and the shell.

[0010] As a further solution of the present invention: there is an annular gap between the nitrogen seal and the main shaft for filling nitrogen, one end of the nitrogen seal abuts against the packing seal to close the opening on one side of the annular gap, and the other end of the nitrogen seal is closed by a lip seal.

[0011] As a further solution of the present invention: the oil immersion length l of the sealing section is:

[0012]

[0013] Wherein, c is the sealing radius gap of the sealing section;

[0014] μ is the dynamic viscosity of the medium in the sealing cavity;

[0015] ω is the angular velocity of the main axis;

[0016] d is the sealing journal length of the sealing section;

[0017] △p is the sealing pressure difference of the sealing section;

[0018] v is the relative thread groove depth of the sealing section;

[0019] α is the helix angle of the sealing section.

[0020] As a further solution of the present invention: the helix angle α of the sealing section is:

[0021]

[0022] As a further solution of the present invention: the large side width a of the thread groove of the sealing section is:

[0023]

[0024] S = πdtanα;

[0025]

[0026] Where, S is the lead of the sealing section;

[0027] i is the number of thread starts in the sealing section.

[0028] Compared with the prior art, the present invention has the following beneficial effects:

[0029] 1. The present invention provides a multi-stage seal on the main shaft to apply an adjustable elastic pressing force to the packing seal in the direction of the sealing section. By dynamically adjusting the pressing force, it can be matched with the use of the melt pump in different working conditions, and the sealing performance is stable.

[0030] 2. Since the oil immersion length has a significant influence on the pressure effect of the spiral seal, when the oil immersion length is too small, the spiral seal cannot achieve the sealing effect, and as the oil immersion length increases, the sealing effect of the spiral seal will continue to improve, but when the oil immersion length increases to a certain extent, continuing to increase the oil immersion length will not continue to increase the sealing effect, but will present an up and down amplitude oscillation effect; the present invention can calculate the optimal oil immersion length of the melt pump under different operating conditions by establishing a calculation formula for the oil immersion length of the spiral seal, so that the spiral seal can meet the sealing effect of the melt pump with the lowest oil immersion length. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 It is a structural schematic diagram of the present invention.

[0032] In the figure:

[0033] 1. Spiral seal; 11. Sealing section; 12. Water cooling jacket;

[0034] 13. guide section; 131. first positioning ring;

[0035] 14. Spring seat; 15. Compression spring; 16. Guide column;

[0036] 2. Sealing chamber; 3. Packing seal; 31. Liquid sealing ring;

[0037] 4. Nitrogen seal; 41. Second positioning ring; 5. Lip seal; 6. Main shaft. DETAILED DESCRIPTION

[0038] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0039] See also Figure 1 In an embodiment of the present invention, a combined seal is suitable for high temperature, high pressure and high viscosity working conditions. A combined seal A is installed on the main shaft 6, and the combined seal A seals the sealing cavity 2 between the main shaft 6 and the pump body.

[0040] The combined seal A includes a spiral seal 1 coaxially fixed on the main shaft 6, and the spiral seal 1 closes the opening of the sealing chamber 2. The spiral seal 1 is a two-stage stepped columnar structure that is narrow at first and wide later, and the spiral seal 1 includes a sealing section 11 and a guide section 13. The sealing section 11 is used to close the opening of the sealing chamber 2. The outer ring of the sealing section 11 is provided with a water-cooling jacket 12. The water-cooling jacket 12 and the sealing section 11 are enclosed to form a water-cooling chamber, and the sealing section 11 is cooled by passing cooling water; the diameter of the water-cooling jacket 12 corresponds to the diameter of the guide section 13, and a sealing ring is provided between the contact surface of the water-cooling jacket 12 and the pump body.

[0041] There is an annular gap between the guide section 13 and the main shaft 6, and a packing seal 3 is filled in the gap. The packing seal 3 includes at least two groups of packings, and a liquid sealing ring 31 is arranged between two adjacent groups of packings.

[0042] The nitrogen seal 4 is coaxially arranged on the main shaft 6, and the sealing seat of the nitrogen seal 4 is inserted into the annular gap between the guide section 13 and the main shaft 6, and the packing seal 3 is pressed and fixed on the sealing section 11. The diameter of the sealing seat of the nitrogen seal 4 corresponds to the inner diameter of the guide section 13, and a sealing ring is arranged on the contact surface of each other. There is an annular gap between the sealing seat of the nitrogen seal 4 and the main shaft 6 for filling nitrogen, and the end of the sealing seat of the nitrogen seal 4 away from the pump body is closed by a lip seal 5.

[0043] The outer ring of the guide section 13 is coaxially and integrally provided with a first positioning ring 131, and the outer ring of the nitrogen seal 4 is coaxially and integrally provided with a second positioning ring 41, and there is a gap between the first positioning ring 131 and the second positioning ring 41. The outer ring of the guide section 13 is also provided with a spring seat 14 located between the first positioning ring 131 and the pump body, and the guide column 16 passes through the first positioning ring 131 and the second positioning ring 41 in a direction parallel to the axis of the main shaft 6 and is connected and fixed to the spring seat 14. The compression spring 15 is coaxially fixed on the guide column 16, and the two ends of the compression spring 15 are respectively in contact with the first positioning ring 131 and the spring seat 14. A locking nut is provided on the guide column 16, and the nitrogen seal 4 is slid toward the spiral seal 1 by tightening the locking nut, thereby adjusting the compression force of the nitrogen seal 4.

[0044] According to the actual operating conditions, the optimal oil immersion length l of the sealing section 11 is calculated as:

[0045]

[0046] Wherein, c is the sealing radius gap of the sealing section 11;

[0047] μ is the dynamic viscosity of the medium in the sealing chamber 2;

[0048] ω is the angular velocity of the main axis 6;

[0049] d is the sealing journal length of the sealing section 11;

[0050] △p is the sealing pressure difference of the sealing section 11;

[0051] v is the relative thread groove depth of the sealing section 11;

[0052] α is the helix angle of the sealing section 11;

[0053]

[0054] In this embodiment, the relationship between the helix angle and the thread groove depth is shown in Table 1 below:

[0055]

[0056] The large side width a of the thread groove of the sealing section 11 is:

[0057]

[0058] S = πdtanα;

[0059]

[0060] Wherein, S is the lead of the sealing section 11;

[0061] i is the number of thread heads of the sealing section 11;

[0062] The thread size design of the spiral seal in this embodiment is shown in Table 2 below:

[0063] Table 2

[0064]

[0065] The basic principles of the present application are described above in conjunction with specific embodiments. However, it should be noted that the advantages, strengths, effects, etc. mentioned in the present application are only examples and not limitations, and it cannot be considered that these advantages, strengths, effects, etc. are required by each embodiment of the present application. In addition, the specific details disclosed above are only for the purpose of illustration and ease of understanding, not for limitation, and the above details do not limit the present application to being implemented by adopting the above specific details.

[0066] The block diagrams of the devices, apparatuses, equipment, and systems involved in this application are only illustrative examples and are not intended to require or imply that they must be connected, arranged, and configured in the manner shown in the block diagram. As will be appreciated by those skilled in the art, these devices, apparatuses, equipment, and systems can be connected, arranged, and configured in any manner. Words such as "including", "comprising", "having", etc. are open words, referring to "including but not limited to", and can be used interchangeably with them. The words "or" and "and" used here refer to the words "and / or" and can be used interchangeably with them, unless the context clearly indicates otherwise. The words "such as" used here refer to the phrase "such as but not limited to", and can be used interchangeably with them.

Claims

1. A combined seal suitable for high temperature, high pressure and high viscosity working conditions, characterized in that: A sealing cavity (2) is provided between the main shaft (6) and the housing. A spiral seal (1) is coaxially arranged on the main shaft (6). The spiral seal (1) comprises a sealing section (11) for sealing an opening of the sealing cavity (2) and a guide section (13) coaxially arranged with the sealing section (11). An annular gap for installing a packing seal (3) is provided between the guide section (13) and the main shaft (6). A nitrogen seal (4) is inserted into the annular gap, and the nitrogen seal (4) and the main shaft (6) are axially slidably matched. The nitrogen seal (4) is subjected to the action of an elastic member to apply an elastic pressing force to the packing seal (3) in the direction of the sealing section (11).

2. A combined seal suitable for high temperature, high pressure and high viscosity working conditions according to claim 1, characterized in that: A first positioning ring (131) is radially arranged on the guide section (13), and a second positioning ring (41) is radially arranged on the nitrogen seal (4) and is arranged in parallel with the first positioning ring (131), and there is a spacing between the first positioning ring (131) and the second positioning ring (41); the elastic member comprises a spring seat (14) coaxially arranged on the outer ring of the guide section (13) and slidingly matched with the guide section (13); a guide column (16) is fixed on the second positioning ring (41) and is arranged in parallel with the axis of the main shaft (6); the guide column (16) passes through the second positioning ring (41) and the first positioning ring (131) in sequence and is fixedly connected with the spring seat (14); a compression spring (15) is coaxially fixed on the guide column (16), and two ends of the compression spring (15) are respectively in contact with the first positioning ring (131) and the spring seat (14); and the nitrogen seal (4) is compressed and fixed by a locking nut on the guide column (16).

3. A combined seal suitable for high temperature, high pressure and high viscosity working conditions according to claim 1 or 2, characterized in that: The packing seal (3) comprises at least two groups of packings, and a liquid sealing ring (31) is arranged between two adjacent groups of packings.

4. A combined seal suitable for high temperature, high pressure and high viscosity working conditions according to claim 1 or 2, characterized in that: The outer ring of the sealing section (11) is coaxially provided with a water cooling jacket (12), and the contact surface between the water cooling jacket (12) and the shell is provided with a sealing ring.

5. A combined seal suitable for high temperature, high pressure and high viscosity working conditions according to claim 1 or 2, characterized in that: There is an annular gap between the nitrogen seal (4) and the main shaft (6) for filling with nitrogen. One end of the nitrogen seal (4) abuts against the packing seal (3) to close the opening on one side of the annular gap, and the other end of the nitrogen seal (4) is closed by a lip seal (5).

6. A combined seal suitable for high temperature, high pressure and high viscosity working conditions according to claim 1 or 2, characterized in that: The oil immersion length l of the sealing section (11) is: Wherein, c is the sealing radius gap of the sealing section (11); μ is the dynamic viscosity of the medium in the sealing chamber (2); ω is the angular velocity of the main axis (6); d is the length of the sealing journal of the sealing section (11); △p is the sealing pressure difference of the sealing section (11); v is the relative thread groove depth of the sealing section (11); α is the helix angle of the sealing section (11).

7. A combined seal suitable for high temperature, high pressure and high viscosity working conditions according to claim 6, characterized in that: The helix angle α of the sealing section (11) is:

8. A combined seal suitable for high temperature, high pressure and high viscosity working conditions according to claim 7, characterized in that: The large side width a of the thread groove of the sealing section (11) is: S = πdtanα; Wherein, S is the lead of the sealing section (11); i is the number of thread starts of the sealing section (11).

Images