RU2541569C1 - Coaxial-rotor helicopter gearbox - Google Patents

Abstract

FIELD: aircraft engineering.

SUBSTANCE: this gearbox comprises housing to accommodate spinning hollow vertical and coaxial shafts. Rotor is fitted on one end of every said shaft. Sump is arranged in housing case and coupled via bearings and tapered gearing with second ends of hollow shafts of upper and lower rotors. Note here that vaned pump wheel is fitted on upper rotor shaft its vanes being arranged at angle α relative to its radius and provided with orifices arranged regularly on its lower end surface, axes of said orifices being parallel with pump wheel axis. Vanes on sump inner surface are arranged at angle α relative to its radius directed opposite inclination of the vanes of said pump wheel. Chamber case is filled with lubricant and communicated via channel, clearances and orifices with bearings and gearings.

EFFECT: higher reliability.

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Description

The invention relates to the field of aircraft construction and can be used in transmissions, mainly of light coaxial helicopters.

Known helicopter gearbox coaxial Ka-26, containing two concentric shafts connected to cylindrical gears of external and internal gears, kinematically, by means of bevel gears and couplings associated with helicopter engines (Vakhitov A.V. Ka-26 helicopter. - M .: Transport, 1973, p. 58 ... 65).

However, despite the fact that the presence of a gear oil pump provides reliable lubrication of the gearbox elements under high pressure, the known gearbox has a complex structure that requires complex seals, which significantly reduces the reliability of the device as a whole.

Known main rotor gearbox containing a housing partially filled with lubricant, a drive shaft with a bevel gear engaged with the rotor shaft wheel, as well as an impeller with vanes and a guide apparatus (Patent No. 2474514 RU. Publish. 02.10.2013).

However, in the known main gearbox there are no axial openings in the impeller between the shaft and the blades, which creates conditions for oil starvation and heat loss, and also does not provide oil supply to the remote bearings of the helicopter propeller column.

Known main gearbox of a helicopter coaxial circuit containing a bevel gear with gear engaged with two bevel wheels placed coaxially to each other and connected with two cylindrical gears, the wheels of which are connected to two coaxially and vertically mounted rotor shafts (Patent No. 2059535 RU. Publ. May 10, 1996).

However, the known invention is notable for its complexity, large mass, and the presence of a large number of highly loaded elements of kinematic pairs, the lubrication of which is carried out by a high pressure oil pump.

The objective of the invention is the creation of a helicopter gearbox coaxial circuit, ensuring reliable operation of gears and bearings through the use of a simple and reliable lubrication system in the conditions of continuous operation on an aircraft, and the result of which is to take into account the required flow rates and the amount of lubricant supplied.

The problem is solved in that in the helicopter gearbox of a coaxial circuit containing a housing, inside of which are vertically and coaxially located the shafts of the upper and lower screws, made hollow and connected with them, as well as with bevel gears that form gears with a bevel gear connected to a cylindrical a gear engaged with a spur gear, said shafts being mounted rotatably relative to the housing by bearings, vertically A pump wheel with blades mounted on its lower surface at an angle relative to its radius and axial holes located between its axis and called blades, as well as an oil pan with similar blades inclined relative to its radius in the opposite direction of inclination of the blades of the said pump wheel side, with blades facing the side of the housing chamber, filled with lubricant, connected by a channel with gaps and calibrated holes , communicating bearings and gearing elements of gears with the specified chamber, in addition, a sleeve is placed inside the shaft of the upper rotor, forming a gap between the inner surface of the said shaft and the sleeve forming a channel for draining used oil into the gear housing.

The present invention is illustrated by a detailed description and drawings, in which:

Figure 1 shows a section of the main view of the helicopter gearbox of a coaxial circuit in a vertical plane according to the invention;

Figure 2 illustrates a section of the gearbox plane AA (partially).

The engine 1 through the clutch 2 is connected to the shaft and the drive gear 3 (Fig.1, 2). The pinion gear 3 has the possibility of engagement with a gear wheel 4 connected to a bevel gear 5 located on a shaft 6 common to it and the wheel 4. Said bevel gear 5 is engaged with two bevel gears 7 connected, respectively, to the shaft of the lower rotor ( NNV) 8 and the shaft of the upper rotor (VNV) 9. The shafts of NNV 8 and VNV 9 have the ability to support bearings 10, 11, 12, 13, 14 and 15 installed in the housing 16. In the lower part of the housing 16 there is an oil pan 17 s blades, and on the shaft of VNV 9 - the pump wheel 18 connected to it holes B and the blades facing downwards (in the drawing). The blades of the oil pan 17 and the pump wheel 18 are inclined relative to the radius by angles, respectively, α and β. Under the vanes of the oil pan 17 in the housing 16, a chamber B is made. Chamber B is connected via a channel G to the gap D through a calibrated hole E with a gap G and, through a calibrated hole I, with a cavity K formed between the axial bore of the shaft ВВВ 9 and the sleeve 19, moreover, the named cavity through the hole L communicates with the internal cavity of the housing 16. The latter is equipped with a pipe 20 with calibrated holes M, oriented vertically. The gear housing 16 is filled with lubricating oil up to level N. The seals 21, 22 and 23 are designed to isolate cavities and gaps. The values of the gaps D and K, as well as the diameters of the calibrated holes E, I and L, are established taking into account the required flow rates Vi and the amount of lubricant supplied, and the condition described by the mathematical expression must be observed

G = 1000 Ci Ai Vi,

where G is the second productivity of the pump wheel, l / s;

Ci is the hydraulic resistance coefficient of a particular section;

Ai is the cross-section on a section of a calibrated hole (mm ² );

Vi - flow rate (m / s);

Z is the number of calibrated holes.

The gearbox of the helicopter coaxial circuit operates as follows.

The rotation of the shaft of the engine 1 through the clutch 2 is transmitted to the bevel wheels 7 by means of gear 3, wheels 4 and bevel gear 5.

The bevel wheels 7 drive the shafts NNV 8 and VNV 9 and the pump wheel 18 connected to the shaft of the VNV 9. The oil entering its blades through holes B enters through the sump blades 17 into the cavity B under excess pressure, which is sufficient to move the oil through the channels G to the holes M of the pipe 20, to the bearing 13 and further through the hole E to the bearing 15 and through the hole And to the cavity K and then through the hole L is discharged into the housing. Part of the oil through the gap between the housing 16 and the shaft NNV 8 enters the bearing 12.

The proposed design of the helicopter gearbox of the coaxial scheme allows for reliable operation of gears and bearings due to the use of a simple and reliable lubrication system in the conditions of continuous operation on an aircraft.

In the proposed design, all bearings serving the rotational motion of the NNV and VNV shafts are reliably lubricated and cooled by the oil contained in the gear housing, which increases the reliability of the helicopter gear.

In addition, the proposed invention allows to take into account the required flow rates and the amount of lubricant supplied. The amount of oil supplied to the bearings and to the gearing zone of the bevel gears is determined by the values of the cross-sections of the clearances D and K and the diameters of the holes E, I and L, selected in accordance with the requirements.

Claims (1)

A helicopter gearbox of a coaxial circuit, comprising a housing, inside which vertically and coaxially located shafts of the upper and lower screws, made hollow and connected with them, as well as with bevel gears, forming gears with a bevel gear connected to a cylindrical gear gear meshed with a spur gear a gear, said shafts being rotatably mounted relative to the housing by means of bearings, characterized in that on a vertically placed shaft An upper impeller is fitted with a pump wheel with vanes made on its lower surface at an angle relative to its radius and axial holes located between its axis and called vanes, as well as an oil sump with similar side inclined relative to its radius in the opposite direction of inclination of the vanes of the said pump wheel , blades facing the housing chamber filled with lubricant connected by a channel with gaps and calibrated holes communicating pniki and gear engagement elements with the specified chamber, in addition, a sleeve is placed inside the shaft of the upper rotor, forming a gap between the inner surface of the shaft and the sleeve forming a channel for draining used oil into the gear housing.

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