RU2718612C1 - Method of controlling axial clearances between centrifugal wheel and housing of turbo-pump unit and device for implementation thereof - Google Patents

Abstract

FIELD: machine building.SUBSTANCE: group of inventions relates to machine building, namely, to machines with rotary rotor, and can be used in development of aircraft turbo-pump units (TPU). In the method for control of axial clearances between the centrifugal wheel and the housing of the TPU, the torque is applied to the rotor of the assembled TPU, under which the rotor rotates. At that, rotor is loaded in turn first, first, and then to other side by axial forces calculated by formula, including: maximum permissible radial static load of radial thrust bearing, safety factor of bearing strength, rotor weight, acceleration of free fall. At that, torque Mis selected from the range depending on friction coefficient in bearing and shaft journal diameter.EFFECT: invention is aimed at providing control of axial gaps between the wheel and the aircraft TPU housing, which ensure the operation reliability of the turbojet.2 cl, 4 dwg

Description

The group of inventions relates to the field of engineering, namely to machines with a rotating rotor, and can be used to create turbopump units (TNA) of aircraft (LA) for various purposes.

A known method of providing axial clearances between a centrifugal wheel and a pump casing [1. Turk, V.I. Pumps and pumping stations / V.I. Turk. - M: Gosstroyizdat, 1961. - P. 89.], in which small gaps of up to 0.25 mm are left between the pump wheel and the casing, which prevents friction between the rotating wheel and the casing and reduces fluid leakage. Reducing the gap is achieved by inserting bronze or cast iron o-rings into the gap between the rotating wheel and the housing. O-rings can be replaced as they wear out.

The disadvantages of this method of providing axial clearances are the complexity of the design and the impossibility of its use in centrifugal pumps with a rotor mass of up to 2 kg, which include TNA LA. If the pump wheel touches the sealing rings, the TNA will jam and break due to the low mass and inertia of the rotor. Another disadvantage of this method is the formation during operation of the chip from the abrasion of the sealing rings and its ingress into the TNA, which can lead to the destruction of bearings, clogging of the filters of the fuel system and accident of the aircraft.

The prototype closest to the claimed method according to the totality of technical features, the method of ensuring axial clearances between the centrifugal wheel and the pump casing by fitting the dimensions of parts that are links of the dimensional chain (rings, gaskets, plates) [2. Pavlovich, L.A., Precision of the manufacture of hydraulic devices for consumable systems / L.A. Pavlovich, S.L. Alexandrov. - M.: Mechanical Engineering, 1986. - S. 28, 29]. According to the proposed method, TNAs are assembled, providing axial clearances between the centrifugal wheel mounted on the rotor and the pump casing. Axial clearances are provided by fitting ring sizes, which are links of the dimensional chain.

The disadvantage of the method chosen as a prototype is the inability to directly control the gaps between the centrifugal wheel and the pump casing during and after fitting axial clearances due to the lack of access for the measuring tool. Clearance of gaps in the unit and their control are carried out using technological rings, recalculated by several measured dimensions, i.e. in an indirect way. As a result of summing the errors of several measurements, the error in fitting gaps increases, and errors due to the human factor are also possible. The situation is aggravated by the fact that in modern pumps, the gaps between the pump wheel and the pump housing are satisfied as permissible in order to reduce pressure losses and increase efficiency. As a result of the action of axial forces on the rotor, the axial clearances during operation of the unit are reduced by the sum of the axial play of the bearing and the constructive axial clearance between the ring and the cover, which reduces the axial clearances by more than two times. Thus, even a small error in fitting axial clearances can lead to the centrifugal wheel touching the pump housing and destroying the TNA. At the same time, an assembly error cannot be detected at any of the stages of manufacture, including during testing of the thermopile, since the modes are limited to preserve the aggregate resource and the integrity of the parking seals.

The inventive method of controlling axial clearances between the centrifugal wheel and the body of the TNA coincides with the prototype according to the following essential feature: the provision of axial clearances is carried out by fitting them to the dimensions of the parts that are links of the dimensional chain.

The aim of the claimed group of inventions is to provide control of axial clearances between the wheel and the body of the TNA LA, guaranteeing the operation of the rotor without jamming.

In the proposed method, the control of axial clearances between the centrifugal wheel and the TNA body is carried out by applying to the rotor of the assembled TNA a torque M _cr , under the influence of which the rotor is rotated. In this case, the rotor is loaded alternately first in one and then in the other direction by axial forces F _a calculated by the formula:

where C ₀ is the maximum permissible radial static load of an angular contact bearing;

K - bearing safety factor from the range K = 5 ÷ 8;

m _p is the mass of the rotor;

g is the acceleration of gravity, g = 9.81 m / s ² .

The plus sign in the formula (1) is placed when the force is applied to the rotor in the up direction, minus - down.

Torque M _cr selected from the range of M _cr ≤ 1.5⋅F _a ⋅μ⋅d,

where μ is the coefficient of friction in the bearing;

d is the diameter of the shaft journal.

The inventive device for implementing a method of controlling axial clearances between a centrifugal wheel and a TNA housing consists of a frame, a device for applying torque, a device for transmitting axial forces with a device for measuring axial forces with an electronic display and a movable docking station. The frame includes the lower, intermediate and upper plates, interconnected by supports. The intermediate plate is made with the possibility of installing TNA in it, and a TNA rotor disk containing a rotating rod is brought out to its upper side. On the upper side of the upper plate there is a device for transmitting axial forces and an electronic board for measuring axial forces. A device for transmitting axial forces contains non-rotating traction. A movable docking unit connects the non-rotating thrust from the device for transmitting axial forces with the rotating thrust from the TNA rotor disk by means of an angular contact bearing.

The group of inventions is illustrated by drawings (FIGS. 1-4), where in FIG. 1 shows a longitudinal section of the TNA; in FIG. 2 is an embodiment of a device for implementing a method for monitoring axial clearances between a centrifugal wheel and a TNA housing; in FIG. 3 is a longitudinal section of a movable docking station of the inventive device; in FIG. 4 is a longitudinal section of the TNA when subjected to axial forces F _a on the rotor.

The group of inventions is as follows.

Perform the assembly of the TNA. Between the centrifugal wheel 1 mounted on the rotor 2 and the housing 3 TNA there are axial clearances Z ₁ Z ₂ , Z ₃ , Z ₄ , which are provided by fitting sizes S ₁ S ₂ , S ₃ , S _{4 of} rings 4, 5, 6, 7 being links of a dimensional chain. The assembled TNA is installed on the device for implementing the method of controlling axial clearances between the centrifugal wheel and the housing of the TNA.

The device is a welded frame consisting of plates: lower 8, intermediate 9 and upper 10, interconnected at four corners of the supports 11. The lower plate 8 is the base of the device. The intermediate plate 9 is used to install the TNA 12. The TNA 12 is mounted on the lower side of the plate 9 using screws 13. The disk 14 of the rotor 2 of the TNA 12 is brought out to the upper side of the plate 9 through the hole 15 in the plate 9. A power plate is installed on the upper plate 10 a screw 16 with a dynamometer 17, a movable docking assembly A and an electronic scoreboard 18. A torque wrench 19 is fastened under the movable docking assembly A.

The movable docking assembly A is assembled and installed on the device as follows. From below, a non-rotating rod 20 connected to the power screw 16 engages a latch 21 and an angular contact bearing 22 is mounted. The bearing 22 is fixed on the non-rotating rod 20 by the end of the inner race of the bearing with a screw 23, which is screwed into the non-rotating rod 20. Further, from below, the outer race of the bearing 22 starts the rotating rod 24 until it stops protruding into the end face of the outer race of the bearing 22. The latch 21 is screwed onto the rotary rod 24 until it stops in the end of the outer race of the bearing 22. Assembled movable joint rotation power screw 16 is lowered down to a compound of the rotating rod 24 with the disk 14 of the rotor 2 THA 12. This operation is the final before testing.

The axial forces F _{a are} calculated according to the formula (1) and are created by rotating the power screw 16. The axial forces F _{a are} transmitted through the movable coupling unit A to the rotor 2, first in one direction and then in the other direction. The value of F _a measured dynamometer 17 and is controlled by an electronic scoreboard 18.

The axial play δ _{1 of the} angular contact bearing 25 is half the value of the axial clearance Z ₁ , Z ₂ , Z ₃ , Z ₄ . As a result of the applied axial force F _a on the rotor 2, the axial clearances Z ₁ , Z ₂ , Z ₃ , Z _{4 are} reduced by the sum of the axial play δ _{1 of the} bearing 25 and the constructive axial clearance δ ₂ between the ring 4 and the cover 26, which reduces the axial clearances more than doubled. Thus, the axial play in the angular contact bearing 25 and between the parts of the TNA are completely eliminated.

When applying to the rotor 2 torque M_cr and axial forces F _a rotation of the rotor 2 of the TNA 12 should be ensured. If the rotor 2 does not rotate and the torque wrench 19 is turned, this means that the fit of the gaps was made with an error and the centrifugal wheel 1 jammed against the housing 3. The TNA 12 is disassembled, the error is eliminated, and the check is repeated. If the results of inspections are positive, TNA is allowed for further production.

The movable docking assembly A provides axial forces F _a to the rotor 2 mechanically, without preventing the rotation of the rotor 2, which is achieved by connecting the non-rotating rod 20 from the power screw 16 with the rotating rod 24 from the disk 14 of the rotor 2 by means of an angular contact bearing 22.

Thus, the technical result of the group of inventions is the control of axial clearances between the wheel and the body of the TNA LA, guaranteeing the reliability of the TNA.

The technical result is achieved by the fact that the control of axial clearances between the wheel and the housing ТНА ЛА is provided:

- application to the rotating thrust from the rotor disc of the TNA of a torque M _cr selected from the range of M _cr ≤ 1.5⋅F _a ⋅μ⋅d, where μ is the friction coefficient in the bearing; d is the diameter of the shaft journal;

- transfer to the rotor of axial forces F _a calculated according to

formula (1), non-rotating thrust from the power screw;

- the connection of non-rotating thrust from the power screw with a rotating thrust from the rotor disk of the TNA in the movable coupling unit by means of an angular contact bearing.

The proposed method and device can be implemented using standard equipment and materials of domestic production. Thus, they meet the criterion of "industrial applicability".

Sources taken into account:

1. Turk, V.I. Pumps and pumping stations / V.I. Turk. - M .: Gosstroyizdat, 1961 .-- 495 p.

2. Pavlovich, L.A., Precision of the manufacture of hydraulic devices for consumable systems / L.A. Pavlovich, S.L. Alexandrov. - M.: Mechanical Engineering, 1986. - 72 p.

3. Pat. 2496985 RU, IPC ⁶ F01C 21/02, F04C 18/16. Axial positioning method for bearings on a shaft journal / Wanneste Sophie Chris (BE), Bernarts Barth (BE) - Decl. 09/27/2010; publ. 10/27/2013, Bull. No. 30.

4. Pat. 159148 RU, IPC ⁶ G01M 13/04, G01B 5/14. A device for measuring axial clearance in spherical bearings / Kolpetsov A.K. et al. - Decl. 04/27/2015; publ. 02/10/2016, Bull. Number 4.

5. Pat. 201464087 CN, IPC G01L 1/04. Motor transmission structure torsion testing device / Xu Jiangchen et al. - Claim. 06/16/2009; publ. 05/12/2010.

Claims (11)

1. A method of controlling axial clearances between a centrifugal wheel and a turbine pump assembly (TNA) housing of an aircraft (LA), in which axial clearances are provided by fitting them to the dimensions of parts that are links in the dimensional chain, characterized in that a torque is applied to the rotor of the assembled TNA M _cr , under the action of which the rotation of the rotor is provided, loaded alternately first to one and then to the other side by axial forces F _a calculated by the formula:

where C ₀ is the maximum permissible radial static load of an angular contact bearing; K - bearing safety factor from the range K = 5 ÷ 8; m _p is the mass of the rotor; g is the acceleration of gravity, g = 9.81 m / s ² ; the plus sign is placed when the force is applied to the rotor in the up direction, minus - down; and the torque M _cr is selected from the range of M _cr ≤ 1.5⋅F _a ⋅μ⋅d, where μ is the coefficient of friction in the bearing; d is the diameter of the shaft journal. 2. A device for implementing a method of controlling axial clearances between a centrifugal wheel and a body of a TNA LA, consisting of a frame including a lower, intermediate and upper plate interconnected by supports, while the intermediate plate is made with the possibility of installing TNA in it, and on the upper side of the intermediate plate, the TNA rotor disk, a device for applying torque, a device for transmitting axial forces with a device for measuring axial forces with an electronic display, and a device for transmitting axial forces The axial and electronic boards of the axial force measuring device are placed on the upper side of the upper plate, characterized in that the TNA rotor disk contains a rotating rod, the axial force transmission device contains a non-rotating rod, while the rotating rod from the TNA rotor disk and a non-rotating rod from the device for axial force transmissions are connected in a movable docking unit by an angular contact bearing.

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