JPH03213749A - Aircraft reduction gear - Google Patents

Abstract

PURPOSE:To reduce a component cost and a service cost through the communization of bearings by setting the twist angles of helical gears so that a dynamic equivalence load to an output shaft side bearing and a dynamic equivalence load to an input shaft side bearing may become of equal life at the same bearing basic dynamic rated load. CONSTITUTION:The rotation of an engine crankshaft is transmitted to an output shaft 12 through an input shaft 11 and a reduction gear row B consisting of three gears 17, 24, 33, and a propeller C assembled to the output shaft 12 is rotated at a rotation number that is reduced at a predetermined reduction ratio against the engine crankshaft rotation. The twist directions of helical gears are set so that an axial load PG due to the meshing of helical gears 24, 33 may act on in the opposite direction from that of an axial load Pp that acts on the output 12 from the propeller C in the state of the maximum engine output/the maximum propeller thrust generation, and also the twist angles psiof respective gears 17, 24, 33 are set so that a dynamic equivalence load to an output shaft 12 side thrust bearing 36 and a dynamic equivalence load to an input shaft 11 side thrust bearing 23 may become of equal life at the same bearing basic dynamic rated load.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to an aircraft reduction gear, and in particular, an input shaft that is integrally connected to the crankshaft of an engine and a propeller are integrally connected. The present invention relates to an aircraft reduction gear comprising an output shaft and a reduction gear train provided between these two shafts to reduce the rotation of the input shaft and transmit the reduced rotation to the output shaft.

[Prior Art] This type of reducer has conventionally been used in the Porsche PFM3200 aircraft engine/reducer, which uses a bearing (thrust bearing) that receives the axial load acting on the output shaft side. The bearings that receive the axial load acting on the input shaft side are not the same part, but are of different sizes. This is because the required capacity of the thrust bearing, which is determined by the axial load, rotation speed, and required life, is different for the output shaft side and the input shaft side.

[Problem to be solved by the invention] Aircraft reducers are made of high-grade materials (for example, steel with reduced impurities) in order to ensure further weight reduction and high reliability compared to vehicle transmissions. Adopt vacuum melted copper for
They often use high-precision parts, and because they are produced in small quantities, the cost of parts is high.

Therefore, as in the above-mentioned conventional technology, using different sizes for the input shaft side bearing and the output shaft side bearing further increases the cost of parts and increases manufacturing costs and service costs at the time of overhaul. .

The present invention has been made to address the above-mentioned problems, and enables the commonality of the input shaft side bearing and the output shaft side bearing, thereby reducing parts costs and reducing manufacturing costs and service costs at the time of overhaul. The purpose is to achieve this goal.

[Means for Solving the Problems] In order to achieve the above object, the present invention includes an input shaft integrally connected to the crankshaft of the engine, an output shaft integrally connected to the propeller, In an aircraft reduction gear comprising a reduction gear train provided between these two shafts to reduce the rotation of the input shaft and transmit it to the output shaft,
Each gear constituting the reduction gear train is a helical gear,
The torsion direction of the helical gear is set so that the axial load due to meshing of the helical gear acts in the opposite direction to the axial load acting on the output shaft from the propeller when the maximum engine output and maximum propeller thrust are generated. and a dynamic equivalent load on the bearing that receives the resultant force of each of the axial loads acting on the output shaft side, and a dynamic equivalent load on the bearing that receives the axial load due to the meshing of the helical gears acting on the input shaft side. The torsion angle of the helical gear was set so that both had the same lifespan at the same basic dynamic load rating.

[Operations and Effects of the Invention] In the aircraft reduction gear according to the present invention, the dynamic equivalent load on the output shaft side bearing and the dynamic equivalent load on the input shaft side bearing are equal at the same bearing basic dynamic load rating. Since the helix angle of the helical gears that make up the reduction gear train was set to ensure a long service life, both bearings for the output shaft side and the input shaft side were installed with approximately the same lifespan when overhauled using the same bearing parts. It is possible to replace each other at the same time without wasting any waste, it is possible to standardize bearings, it is possible to reduce parts costs, and it is possible to reduce manufacturing costs and service costs at the time of overhaul.

In addition, by standardizing bearings, the structure of the bearing mounting part can be standardized, reducing manufacturing costs (processing and assembly costs, etc.), and the strength of the casing that supports the bearings can be made uniform, making it lighter. It becomes easier to design the structure.

(Example) An embodiment of the present invention will be described below with reference to the drawings.

1 to 4 show an aircraft reduction gear according to the present invention, which includes a casing A and an input shaft 11. It is composed of an output shaft 12, a reduction gear train B, etc., and the casing A is composed of a front case 13 and a rear case 14.

The input shaft 11 has a rear end (right end in the figure) fitted into a coupling 16 assembled to the crankshaft 15 of the engine so as to be able to slide in the axial direction and rotate integrally with the coupling 16, and a front end (right end in the figure).
It is coaxially fitted to a hollow input gear 17 at the left end (in the figure) and spline-fitted so as to be rotatable together, and is positioned in the axial direction by a snap ring 18. Note that a seal member 19 is assembled between the central outer periphery of the input shaft 11 and the rear case 14.

The input gear 17 is a helical gear as shown in FIG. 1, and as shown in FIG. 21.22 and one thrust bearing (
It is rotatably supported via a ball bearing (23) having a radial gap between the constituent members in order to share only the axial load, and is configured to be rotated integrally by the input shaft 11. As shown in FIGS. 1 and 3, it is constantly meshed with the intermediate gear 24. The inner rings of both front bearings 21 and 23 are integrally fixed to the input gear 17 by a fastener 25 screwed onto the input gear 17, and the outer ring of the thrust bearing 23 is fixed to the front case 13 using a fastener 26. The front case 13 is fixed by the fixed retainer 27.
is integrally fixed to.

The intermediate gear 24 is a helical gear as shown in FIG. 1, and as shown in FIG. The shaft is rotatably supported via bearings 〉31゜32, and rotates integrally with the output shaft 12 by being spline-fitted onto the output shaft 12 as shown in Figs. 1 and 4. The helical gear (see FIG. 1) is always in mesh with the output gear 33 (see FIG. 2), and connects the input gear 17 and the output gear 33 so that power can be transmitted.

On the other hand, as shown in FIG. 2, the output shaft 12 is formed in a hollow shape, and has a pair of radial bearings (cylindrical roller bearings that share only the radial load) 34.35 in both cases 13.14. It is rotatably supported via one thrust bearing (a ball bearing with a radial gap between the constituent members to share only the axial load) 36, and an annular flange 37 provided at the front end has a first The propeller C is ready to be assembled as schematically shown in the figure. The inner rings of both front bearings 34 and 36 are integrally fixed to the output shaft 12 together with the output gear 33 by a fastener 38 screwed onto the output shaft 12, and the outer ring of the thrust bearing 36 is fixed to the output shaft 12 using a fastener 39. It is integrally fixed to the front case 13 by a retainer 41 fixed to the front case 13.

Further, a seal member 42 is assembled between the front end neck of the output shaft 12 and the front case 13.

With the above configuration, the rotation of the engine crankshaft 15 is transmitted to the output shaft 12 via the input shaft 11 and the reduction gear train B consisting of three gears 17, 24, 33, and the propeller assembled to the output shaft 12. C is rotated at a rotation speed that is reduced by a predetermined reduction ratio with respect to the rotation of the engine crankshaft 15.

In addition, in this embodiment, a variable pitch propeller is attached as the propeller, and as shown in FIG. 2, pressure oil for the variable pitch propeller is discharged from the rear end of the output shaft 12. A booster pump D and a hydraulic control device E for controlling pressure oil to the variable pitch propeller are assembled, but since these structures are not directly related to the present invention, their explanation will be omitted.

By the way, in this embodiment, the axial load Pp(
In the case of a tractor type, which is a general propeller airplane,
As shown in Figure 1, the axial load P due to the meshing of the helical gears 24 and 33 acts in the opposite direction.
The torsion direction of the helical gear is set as shown in FIG. 1 in order for G to act, and the dynamic equivalent load POUT on the thrust bearing 36 on the output shaft 12 side and the dynamic equivalent load POUT on the thrust bearing 23 on the input shaft 11 side are set as shown in FIG. Each gear 17 has the same lifespan with the same bearing basic dynamic load rating C1 as the load PIN.
, 24.33 torsion angle ψ is set. (JIS
(Refer to B1518) In general, when cruising, an impact aircraft generates an output of about 50% to 80% of the maximum engine output.

Therefore, the life times Lh(36) and Lh(23) of each thrust bearing 23.36 are generally determined by the following equation.

However, 2NE is the rotational speed (rpm) of the engine crankshaft 15.
) is a constant 0 determined by the bearing type (Ball bearing n・3. Roller bearing n・(-) Also, the dynamic equal unbalanced load P of each thrust bearing 36°3. Ll↑+PIN is generally determined by the following formula.

POUT ・YOUT X (PP-PG) ・・
・(3) PIN-YINxPG...(4) The above axial load P. As is clear from the schematic diagrams showing the axial load generation mechanism in FIGS. 5 and 6, it is obtained by the following formula, and as shown in FIG.
4 is the axial load P from the input gear 17. is the axial load P from the output gear 33. offset by

Po ” Pt, .X tanψ is the pressure angle and P
rad is the radial load at the meshing point.

Therefore, in this embodiment, the following equation is satisfied based on the relationships among the above equations and the setting conditions for the torsion angle ψ (equal lifespan of the thrust bearing).

Lb (23) = Lh (36) l γ In this embodiment configured as described above, the dynamic equivalent load P on the thrust bearing 36 for the output shaft side. Dynamic equivalent load PI on thrust bearing 23 for ut and input shaft side
The helical gears 17 and 24 constituting the reduction gear train B are designed so that N has the same bearing basic dynamic load rating C@ and has an equal life.
．． Since the helix angle ψ of 33 is set, both thrust bearings 36.23 for the output shaft side and the input shaft side can be replaced at the same time with approximately the same lifespan during overhaul using the same bearing parts, without waste. It is possible to reduce component costs by standardizing the parts, and it is also possible to reduce manufacturing costs and service costs at the time of overhaul.

In addition, by standardizing the thrust bearings 36 and 23, the structure of the bearing mounting part (mounting hole machining in the case 13 and bearing fixtures such as retainers and fasteners) can also be standardized, and manufacturing costs (processing 2 assembly costs, etc.) can be standardized. ), and the strength of the casing supporting the bearing can be made uniform, making it easier to design a lightweight structure.

In the above embodiment, the reduction gear train includes three gears 17,
24.33, and the rotational direction of the engine is the same as the rotational direction of the propeller. However, in the present invention, the reduction gear train is composed of two gears and the rotational direction of the engine and the propeller are the same. The same can be applied to a reduction gear whose rotation direction is reversed.

[Brief explanation of drawings]

Fig. 1 is a schematic exploded view of each axis of the aircraft reduction gear according to the present invention, Fig. 2 is a detailed vertical sectional side view of the input shaft and output shaft portions of the reduction gear, and Fig. 3 is the same reduction gear. Fig. 4 is a longitudinal sectional view showing the relationship between the reduction gear train of the same reducer, and Figs. 5 and 6 show the axial load generation mechanism due to gear meshing. It is a schematic diagram. Explanation of symbols 11... Input shaft, 12... Output shaft, 15... Engine crankshaft, C... Propeller, B... Reduction gear train, 17, 24. 33... Helical Gear, ψ...Helix angle, 23...Thrust bearing (bearing for output shaft side), 36...Thrust bearing (bearing for input shaft side)
.

Claims (1)

[Claims] An input shaft that is integrally connected to the crankshaft of the engine, an output shaft that is integrally connected to the propeller, and a speed reducer that is provided between these two shafts to reduce the rotation of the input shaft and transmit it to the output shaft. In an aircraft reduction gear comprising a gear train, each gear constituting the reduction gear train is a helical gear, and an axial load is applied from the propeller to the output shaft in a state where maximum engine output and maximum propeller thrust are generated. The torsional direction of the helical gear is set so that the axial load due to meshing of the helical gear acts in the opposite direction, and the movement to the bearing receives the resultant force of the axial loads acting on the output shaft side. The helical gear is designed so that the equivalent load and the dynamic equivalent load on the bearing that receives the axial load due to the meshing of the helical gear acting on the input shaft side have the same lifespan at the same bearing basic dynamic load rating. An aircraft reduction gear characterized by having a helix angle of .