CN114215921A - Method for determining wave spring force of high-speed mechanical seal - Google Patents
Method for determining wave spring force of high-speed mechanical seal Download PDFInfo
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- CN114215921A CN114215921A CN202111432807.9A CN202111432807A CN114215921A CN 114215921 A CN114215921 A CN 114215921A CN 202111432807 A CN202111432807 A CN 202111432807A CN 114215921 A CN114215921 A CN 114215921A
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- 238000000034 method Methods 0.000 title claims abstract description 26
- 238000007789 sealing Methods 0.000 claims abstract description 72
- 230000003068 static effect Effects 0.000 claims abstract description 51
- 238000001816 cooling Methods 0.000 claims abstract description 12
- 239000010687 lubricating oil Substances 0.000 claims abstract description 11
- 239000003921 oil Substances 0.000 claims abstract description 5
- 239000002826 coolant Substances 0.000 claims description 9
- 239000013256 coordination polymer Substances 0.000 claims description 6
- 239000005068 cooling lubricant Substances 0.000 claims description 3
- 230000010355 oscillation Effects 0.000 claims description 3
- 230000005540 biological transmission Effects 0.000 description 3
- 238000005299 abrasion Methods 0.000 description 2
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 description 1
- 238000006243 chemical reaction Methods 0.000 description 1
- 238000010586 diagram Methods 0.000 description 1
- 238000006073 displacement reaction Methods 0.000 description 1
- 238000000605 extraction Methods 0.000 description 1
- 229910002804 graphite Inorganic materials 0.000 description 1
- 239000010439 graphite Substances 0.000 description 1
- 238000009434 installation Methods 0.000 description 1
- 239000000463 material Substances 0.000 description 1
- 238000000926 separation method Methods 0.000 description 1
- 238000006467 substitution reaction Methods 0.000 description 1
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
- F16J—PISTONS; CYLINDERS; SEALINGS
- F16J15/00—Sealings
- F16J15/16—Sealings between relatively-moving surfaces
- F16J15/34—Sealings between relatively-moving surfaces with slip-ring pressed against a more or less radial face on one member
- F16J15/3436—Pressing means
- F16J15/3452—Pressing means the pressing force resulting from the action of a spring
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- Engineering & Computer Science (AREA)
- General Engineering & Computer Science (AREA)
- Mechanical Engineering (AREA)
- Mechanical Sealing (AREA)
Abstract
The application provides a method for determining a wave spring force of a high-speed mechanical seal, which comprises the following steps: determining the resultant gas force borne by the static sealing ring according to the structural form of the static sealing ring; determining the inertia force of the static sealing ring; the wave spring force is made to be larger than the difference value of the inertia force and the resultant force of the gas force, so that the minimum value of the wave spring force is determined; and determining the friction heat generated by the relative sliding of the static sealing ring and the dynamic sealing ring in the working process according to the temperature rise of the cooling lubricating oil, and obtaining the maximum value of the wave spring force according to the friction heat so as to determine the magnitude of the wave spring force. According to the method, under a certain working condition, friction heat generated under the combined action of the wave spring force and the gas force when the temperature of the mechanical seal cooling sliding oil rises is calculated, then the gas force value is calculated, and the maximum wave spring force value of the temperature rise of the sliding oil within the range is obtained through back calculation, so that the proper high-speed mechanical seal wave spring force can be determined, and the problem of disengagement or failure damage caused by improper wave spring force selection during high-speed mechanical seal design is solved.
Description
Technical Field
The application belongs to the technical field of aero-engine design, and particularly relates to a method for determining a wave spring force of a high-speed mechanical seal.
Background
With the gradual increase of the extraction of the transmission power in the aircraft engine and the development of the axial miniaturization of the transmission, the rotating speed of the accessory transmission shaft is higher and higher, the requirement on the mechanical seal is correspondingly improved, and the mechanical seal needs to adapt to the working environment with high linear speed, high working temperature and high working pressure. The mechanical seal with the wave spring is widely applied to the aeroengine due to the characteristics of compact structure, short axial size, large rigidity, small axial displacement and the like.
The selection of the wave spring force of the wave spring is very important for the design of high-speed mechanical seal, and the small wave spring force can cause the separation of the sealing end surface between the static sealing ring and the dynamic sealing ring in actual work, so that the leakage amount is greatly increased; the overlarge wave spring force can cause the specific pressure of the end face generated by the wave spring to be overlarge, so that the abrasion of the sealing end face can be accelerated, the service life of mechanical sealing is shortened, and the static sealing ring is seriously damaged due to overlarge friction heat, so that the sealing failure is caused.
The existing design method mainly determines the wave spring force value of the mechanical seal through calculation of a PV value (pvvalue), but for the high-speed mechanical seal, the sealing linear velocity is very high, so that the PV value is very high, the PV value may exceed the allowable limit of materials according to the recommended end face specific pressure value, and the proper wave spring force value in the design of the high-speed mechanical seal cannot be obtained.
Disclosure of Invention
It is an object of the present application to provide a method of determining a wave spring force of a high speed mechanical seal that solves or mitigates at least one of the problems of the background art.
The technical scheme of the application is as follows: a method of determining a wave spring force of a high speed mechanical seal, the method comprising:
determining the resultant gas force borne by the static sealing ring according to the structural form of the static sealing ring;
determining the inertia force of the static sealing ring;
the wave spring force is made to be larger than the difference value of the inertia force and the resultant force of the gas force, so that the minimum value of the wave spring force is determined;
and determining the friction heat generated by the relative sliding of the static sealing ring and the dynamic sealing ring in the working process according to the temperature rise of the cooling lubricating oil, and obtaining the maximum value of the wave spring force according to the friction heat so as to determine the magnitude of the wave spring force.
Further, the structural form of the static sealing ring comprises a balance type static sealing ring.
Furthermore, one side of the balance type static sealing ring, which is in contact with the dynamic sealing ring, is provided with a plane, the section of the plane is S1, the opposite side of the plane is provided with a double-step surface, and the sections of the double-step surface are S2, S3 and S4 respectively;
the resultant gas force corresponding to the section S1 is
The resultant gas force corresponding to the section S2 is
The resultant gas force corresponding to the section S3 is
The resultant gas force corresponding to the section S4 is
In the formula, P0 is the low pressure side pressure communicated with the outside air, P1 is the high pressure side pressure of the seal cavity, D1 is the distance from the section S1 to the rotation center, D2 is the distance from the section S2 to the rotation center, D is the distance from the section S3 to the rotation center, and D3 is the distance from the section S4 to the rotation center.
Further, the inertia force generated by simple harmonic motion when the static sealing ring works is as follows:
Fg＝M/(0.5·d1)
in the formula, FgIs the inertial force of the seal ring; m is the moment of the simple harmonic oscillation of the sealing ring, wherein,
j is the moment of inertia of the sealing end face of the rotary sealing ring, delta is the end face bounce amount, omega is the rotation angular velocity of the rotary ring, and d1Is the sealing flange outer diameter.
Further, the friction heat generated by the relative sliding of the static sealing ring and the dynamic sealing ring during the operation is as follows:
W＝μ·Fb·V
in the formula: mu is the friction coefficient between the static sealing ring and the dynamic sealing ring; fb is the positive pressure between the static sealing ring and the dynamic sealing ring, namely the maximum wave spring force and the resultant gas force are the positive pressure; v is the linear velocity of friction.
Further, the frictional heat and the temperature rise of the cooling lubricant per unit time have a relationship according to the following formula:
Qv＝0.06W/ρ·CP·ΔT
in the formula: qv is the amount of cooling oil per unit time; ρ is the density of the cooling medium; CP is the constant pressure heat capacity of the cooling medium; Δ T is the temperature rise of the cooling medium.
Drawings
In order to more clearly illustrate the technical solutions provided by the present application, the following briefly introduces the accompanying drawings. It is to be expressly understood that the drawings described below are only illustrative of some embodiments of the invention.
Fig. 1 is a schematic view of a mechanical seal structure according to an embodiment of the present application.
Fig. 2 is a flowchart of a wave spring force determination method according to the present application.
Fig. 3 is a schematic view of a static seal ring structure according to an embodiment of the present application.
Fig. 4 is a schematic gas force diagram of the static seal ring structure shown in fig. 3.
Detailed Description
In order to make the implementation objects, technical solutions and advantages of the present application clearer, the technical solutions in the embodiments of the present application will be described in more detail below with reference to the drawings in the embodiments of the present application.
In order to solve the problem of sealing failure caused by unreasonable wave spring force selection in high-speed mechanical seal design, the application provides a novel method for determining the wave spring force of the high-speed mechanical seal.
The basic structure of the high-speed mechanical seal shown in fig. 1 comprises a static seal ring 11, a dynamic seal ring 12, a seal housing 13, a wave spring 15 and an auxiliary seal ring 14, wherein the static seal ring 11 is pushed against the dynamic seal ring 12 by the action of the wave spring force to realize sealing in a cavity. The wave spring force is too small, so that the static sealing ring 11 and the dynamic sealing ring 12 are separated in the working process, and leakage occurs; the wave spring force is too large, so that the friction force between the static sealing ring 11 and the dynamic sealing ring 12 is increased, further, the friction heat productivity is too large, the abrasion of the sealing end face is accelerated, the service life of the mechanical seal is shortened, and the sealing failure is serious or even caused.
As shown in fig. 2, the wave spring force determination method of the present application specifically includes the processes of:
s10, determining the structural form of the static sealing ring, and determining the resultant gas force borne by the static sealing ring in the structural form by analyzing the gas force of the static sealing ring;
s20, determining the inertia force of the static sealing ring;
s30, enabling the wave spring force to be larger than the difference value of the inertia force and the resultant force of the gas force, and accordingly determining the minimum value of the wave spring force;
and S40, determining the friction heat generated by the relative sliding of the static sealing ring and the dynamic sealing ring in the working process according to the temperature rise of the cooling lubricating oil, and obtaining the maximum value of the wave spring force according to the friction heat so as to determine the magnitude of the wave spring force.
Taking the balanced mechanical static seal ring 11 shown in fig. 3 as an example for explanation, the side of the balanced mechanical static seal ring 11 in contact with the dynamic seal ring 12 is a plane, the cross section of the plane is S1, the opposite side of the plane is a double step surface, the cross sections of the double step surfaces are S2, S3 and S4, respectively, the gas force applied to the static seal ring 11 is shown in fig. 4, wherein P0 is the low-pressure side pressure communicated with the outside air, P1 is the high-pressure side pressure of the seal cavity, the left and right pressures of the static seal ring 11 at the parts above the dotted line are offset, and the gas force applied is the resultant force applied to the cross sections S1, S2, S3 and S4, that is:
where D1 is the distance from the center of rotation of section S1, D2 is the distance from the center of rotation of section S2, D is the distance from the center of rotation of section S3, and D3 is the distance from the center of rotation of section S4.
The total force F generated by the gas load on the static seal ring 11 is: f2+ F3+ F4-F1.
According to the simple harmonic vibration of the static sealing ring 11 in the working process, the inertia force, namely F, generated when the static sealing ring 11 works can be calculatedg＝M/(0.5·d1)
In the formula: fgIs the inertial force of the seal ring; m is the moment of the simple harmonic oscillation of the sealing ring, wherein,
j is the moment of inertia of the sealing end face of the dynamic sealing ring 12, delta is the end face run-out (the run-out obtained by conversion of the installation reference is usually not more than 0.05mm), omega is the rotation angular velocity of the rotating ring, d1Is the sealing flange outer diameter.
In order to ensure that the static sealing ring 11 and the dynamic sealing ring 12 are not separated in the working process, the sealing surfaces of the static sealing ring 11 and the dynamic sealing ring 12 are always attached, and the total resultant force F of gas force and the resultant force of wave spring force are larger than the inertial force of the sealing ring in working, so that the minimum value F of the wave spring force can be obtainedmin。
Because the high-speed mechanical seal has high working temperature and high linear friction speed, a large amount of friction heat can be generated on the seal end face, the seal ring is usually cooled by adopting lubricating oil with a certain flow, most of the friction heat needs to be taken away by the cooling lubricating oil, and the heat crack caused by overhigh temperature of the graphite seal end face is prevented. Under the working condition of giving a certain cooling lubricating oil amount, the maximum value of the wave spring force under the working condition is judged by evaluating the temperature rise of the cooling lubricating oil. Firstly, friction heat under the action of the wave spring force and gas resultant force when the temperature of the lubricating oil rises to 20-30 ℃ is obtained through calculation, and then the maximum wave spring force value when the temperature of the lubricating oil rises within a reasonable range is obtained through inverse calculation.
The friction heat generated by the relative sliding between the static seal ring 11 and the dynamic seal ring 12 during the operation is as follows:
W＝f·V＝μ·Fb·V
in the formula: w is the work done by friction; mu is the friction coefficient between the static seal ring 11 and the dynamic seal ring 12; fb is the positive pressure between the static seal ring 11 and the dynamic seal ring 12, i.e. the wave spring force maximum value FmaxThe resultant force F of the qi and the body is positive pressure; v is the linear velocity of friction; f is the friction.
The relationship between the frictional heat and the temperature rise of the cooling lubricant in unit time is as follows:
Qv＝0.06W/ρ·CP·ΔT
in the formula: qv is the amount of cooling oil per unit time; ρ is the density of the cooling medium; CP is the constant pressure heat capacity of the cooling medium; Δ T is the temperature rise of the cooling medium.
The maximum wave spring force allowed under the condition of effective lubricating oil cooling can be reversely deduced by combining a friction heat formula and a temperature rise formula, and the magnitude of the mechanical sealing wave spring force under certain application conditions can be determined by combining the minimum wave spring force obtained by previous calculation.
The above description is only for the specific embodiments of the present application, but the scope of the present application is not limited thereto, and any changes or substitutions that can be easily conceived by those skilled in the art within the technical scope of the present application should be covered within the scope of the present application. Therefore, the protection scope of the present application shall be subject to the protection scope of the claims.
Claims (6)
1. A method for determining a wave spring force of a high-speed mechanical seal is characterized by comprising the following steps:
determining the resultant gas force borne by the static sealing ring according to the structural form of the static sealing ring;
determining an inertial force of the static seal ring;
the wave spring force is made to be larger than the difference value of the inertia force and the resultant force of the gas force, so that the minimum value of the wave spring force is determined;
and determining the friction heat generated by the relative sliding of the static sealing ring and the dynamic sealing ring in the working process according to the temperature rise of the cooling lubricating oil, and obtaining the maximum value of the wave spring force according to the friction heat so as to determine the magnitude of the wave spring force.
2. The method for determining the wave spring force of a high-speed mechanical seal according to claim 1, wherein the static seal ring is structured to include a balanced static seal ring.
3. The method for determining the wave spring force of a high-speed mechanical seal according to claim 1, wherein one side of the balanced type static seal ring, which is in contact with the dynamic seal ring, has a plane with a cross section of S1, and the opposite side of the plane is a double-step surface with cross sections of S2, S3 and S4;
the resultant gas force corresponding to the section S1 is
The resultant gas force corresponding to the section S2 is
The resultant gas force corresponding to the section S3 is
The resultant gas force corresponding to the section S4 is
In the formula, P0 is the low pressure side pressure communicated with the outside air, P1 is the high pressure side pressure of the seal cavity, D1 is the distance from the section S1 to the rotation center, D2 is the distance from the section S2 to the rotation center, D is the distance from the section S3 to the rotation center, and D3 is the distance from the section S4 to the rotation center.
4. The method for determining the wave spring force of the high-speed mechanical seal according to claim 3, wherein the inertia force generated by the simple harmonic motion of the static seal ring during the operation is as follows:
Fg＝M/(0.5·d1)
in the formula, FgIs the inertial force of the seal ring; m is the moment of the simple harmonic oscillation of the sealing ring, wherein,
j is the moment of inertia of the sealing end face of the rotary sealing ring, delta is the end face bounce amount, omega is the rotation angular velocity of the rotary ring, and d1Is the sealing flange outer diameter.
5. The method for determining the wave spring force of the high-speed mechanical seal according to claim 3, wherein the friction heat generated by the relative sliding of the static seal ring and the dynamic seal ring during the operation is as follows:
W＝μ·Fb·V
in the formula: mu is the friction coefficient between the static sealing ring and the dynamic sealing ring; fb is the positive pressure between the static sealing ring and the dynamic sealing ring, namely the maximum wave spring force and the resultant gas force are the positive pressure; v is the linear velocity of friction.
6. The method for determining the wave spring force of a high-speed mechanical seal according to claim 5, wherein the frictional heat and the temperature rise of the cooling lubricant per unit time have a relationship according to the following equation:
Qv＝0.06W/ρ·CP·ΔT
in the formula: qv is the amount of cooling oil per unit time; ρ is the density of the cooling medium; CP is the constant pressure heat capacity of the cooling medium; Δ T is the temperature rise of the cooling medium.
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| CN202111432807.9A CN114215921A (en) | 2021-11-29 | 2021-11-29 | Method for determining wave spring force of high-speed mechanical seal |
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN117605837A (en) * | 2024-01-23 | 2024-02-27 | 成都晨发泰达航空科技股份有限公司 | Sealing structure for high-rotation-speed shaft |
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2021
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| CN117605837A (en) * | 2024-01-23 | 2024-02-27 | 成都晨发泰达航空科技股份有限公司 | Sealing structure for high-rotation-speed shaft |
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