TW201346155A - Single-stage large-ratio reducer gearbox for aero engine - Google Patents

Abstract

A single-stage speed reducer gearbox for aero engine for changing an input speed at an input shaft connected to a turbine shaft of the aero engine to an output speed at an output shaft connected to a fan blade shaft of the aero engine. The gearbox has a coaxial pair of ring gears including a large ring gear having a pitch diameter A and a small ring gear having a pitch diameter D. A coaxial pair of spur gears includes a large spur gear having a pitch diameter B and a small spur gear having a pitch diameter C. The large spur gear meshes with the large ring gear and the small spur gear meshes with the small ring gear, forming two meshing pairs. A carrier member is connected to the input shaft of the gearbox. Two gears of one of the two coaxial pairs are fixed together to operate epicyclically on the carrier. One gear of the other of the two coaxial pairs is fixed to the frame of the gearbox and the other gear is connected to the output shaft. The four gears satisfy the dimensional relationship of A = K+i, B = K, C = K-j and D = K+i-j-j, wherein K, i and j are integers.

Description

Single-stage large-scale reduction gearbox for aviation engines

The present invention relates generally to jet engines, and in particular to a reducer gearbox having a single stage, a large proportion, a dense and high power density for a jet engine.

Reduction gearboxes are required for aero engines such as turboprops, geared turbofan engines (GTF), open rotors, and turboshafts. Because their low-speed blade shafts must operate at lower speeds than the high-speed turbine shafts that they drive, these aerospace engines require gearboxes that use considerable reduction ratios. For helicopter turboshaft engines, or variant engines for onshore or offshore applications, gearboxes with large reduction ratios are also necessary. This is why the engine is used as the prime mover, which is operated at a speed much higher than the load it drives (such as the rotor of a helicopter, the drive wheel of a land-based vehicle, and the propeller of a marine ship). The best way currently used by aerospace engines to achieve such large-scale deceleration is to use several series of gearboxes with relatively low reduction ratios and high efficiency.

However, since the entire load of the deceleration system must be successively passed through each of the individual speed reducers in the series, the tandem speed reduction practice of the tandem front and back will essentially reduce the overall speed conversion efficiency. The problem. In addition, because each individual series of stages in the system must have sufficient power to withstand the entire system, and the 100% total power generated by the turbine blades is obvious, this tandem arrangement also changes the entire system. It’s huge and bulky.

A single-stage large-ratio reducer can overcome the problems caused by such cascades. Currently widely used is a "single stage" type of speed conversion device which is a cycloidal drive manufactured by Sumitomo Heavy Industries, Ltd., Tokyo, Japan. Although it has a relatively dense structure in the range of speed conversion ratio from tens to more than one hundred to one, such a cycloidal driver, when used as a reducer, is essentially a cycloidal gear. A cycloidal gearing stage is coupled to a system configuration of an off-axis power extraction stage.

Figure 1 shows in cross section a cross section of such a cycloidal speed reducer. The prior art device of Figure 1 has a fixed ring gear (or internal gear) 11 and a specially shaped planet element 12, which may be a shaped disc or may be simple. The ground is for a gear. The planet element 12 engages with the ring gear 11 and engages in a planetary motion (moves inside epicyclically). The difference between the working pitch diameters (or, the pitch pitch diameters) is as small as possible.

The off-axis power take-up stage has a disc 13 coaxially fixed to the planet element 12 on the axis 19, and has a plurality of circular holes 17 open therein to allow for respectively a disc (plate) 14 is the engagement of each of the same number of roller pins 18. The circular plate 14 is coupled to the output shaft 16 of the reducer and is aligned with the central axis 10 of the overall system arrangement. These "power draw" mechanisms allow the cycloid reducer to produce a -K/i speed reduction ratio, where K is the pitch diameter of the planet element 12 and i is the pitch between the components 11 and 12. The difference. In a typical example in which the ring gear 11 is 80 teeth and its gear type planetary element 12 is 79 teeth (K=80 and i=1), when the mechanical power transmitted by the reducer is input via the shaft 15, The reduction ratio of this system is -80.

2 is a schematic view showing the off-axis power extraction coupling mechanism used in the conventional cycloidal speed reducer of FIG. 1. At any one time, only one of the typically eight or more rollers that engage the holes in the cycloidal disc transmits torque at full force. For example, in the case of the off-axis relative angular position and the direction of rotation shown in the figure, only the pairing of the rollers 18C and the holes 17C in the system is transmitting power with full force.

The above is obvious because the edge of the hole 17C of the drive disk 13 and the roller 18C of the driven plate 14 are in contact with each other, and must be located behind the roller 18C in the direction of rotation, and the drive plate 13 can drive the driven plate. 14. According to this principle, since the contact point of the pair of rollers and the holes is opposite to the direction of rotation of the disk 13 and the plate 14, the pair of rollers and holes indicated as B and D in the figure only locally generate power transmission. effect. By the same principle, since the driven roller 18G is advanced to the rear of the hole 17G which is supposed to be driven, the pairing of the roller 18G and the hole 17G does not have any transmission at all.

Conventional cycloidal gear reducers must rely on their axes to deviate from each other, and simultaneous engagement between two components (gears) of different pitch diameters can be operated. However, due to the aforementioned low utilization ratio, such a mechanism is not an optimized structure: half of all eight pairs of rollers and holes in Figure 2 (ie four to five pairs, depending on the angular position) ) failed to be in the position to drive the load. Among the other half of the pairing, only one pair can be in the position where the full force is driven, and the remaining three pairs only produce a partial driving effect. Due to such limitations, cycloidal gear reducers typically achieve only about 80% efficiency under normal load conditions.

In addition, in order to achieve the reduction ratio K, the cycloidal gear reducer must have a fixed ring gear with K+1 teeth. To achieve a large reduction ratio, when it is necessary to load a considerable rated torque, it is necessary to use a large tooth with a large size. In the case of shape, the large number of teeth of the ring gear makes the reducer bulky and bulky. In other words, if the cycloidal speed reducer is to be made denser, its rated torque and power will be limited.

Another type of large-scale reducer that is currently widely used in precision and aerospace applications is a harmonic drive manufactured by Harmonic Drive Systems Inc. of Tokyo, Japan. Utilizing the basic operating principle of strain wave gearing, the rated power that can be achieved by tuning the reducer is relatively low. Since the spline element is twisted and deformed at any time during the operation of the transmission, the tuned reducer can usually achieve an efficiency of less than about 60% under normal load conditions.

It is an object of the present invention to provide a single stage reduction gearbox for an aero engine that provides a large scale deceleration speed conversion device for use with an aero engine for relatively small number of gears of as few as ten or twenty teeth.

It is an object of the present invention to provide a single stage, large scale, reduced speed gearbox for an aerospace engine for constructing a high power density aero engine gearbox with a small gear fraction of a large gear modulus.

It is also an object of the present invention to provide a single stage, large scale reduction gearbox for an aero engine for high efficiency use of an aero engine.

To achieve the above and other objects, the present invention provides a single-stage reduction gearbox for an aircraft engine that can be coupled to an input speed of an input shaft of a turbine shaft of an aircraft engine and converted into one of the blade shafts coupled to the aircraft engine. Output shaft output speed. The gearbox includes a pair of coaxial ring gears including a large ring gear having a pitch diameter of A and a small ring gear having a pitch diameter D. There is also a pair of coaxial spur gears, which include a large spur gear having a pitch diameter of B and a small spur gear having a pitch diameter of C. The large spur gear meshes with the large ring gear teeth, and the small spur gear meshes with the small ring gear teeth to form two sets of tooth bite pairs. There is also a planet carrier assembly that is coupled to the input shaft of the gearbox. Wherein, two of the two pairs of coaxial pairs are paired with each other to fix the two sets of coaxial pairs on the planet carrier, and one of the pair of coaxial pairs is fixed on the frame of the gearbox. And the other gear is connected to the output shaft of the gearbox. The four gears satisfy the dimensional relationship of A=K+i, B=K, C=K-j and D=K+i-j, where K, i and j are integers.

Figure 3 is a schematic view showing a cross section of a rotational speed conversion device according to the present invention, wherein the device of the present invention is shown It is equivalent to an equivalent mechanism of the conventional off-axis dynamic extraction stage configuration. 1 and 2, the speed conversion device of the present invention in FIG. 3 replaces the plate 14 having the plurality of rollers 18 and the cycloidal disk 13 having the same number of corresponding holes 17 engaged therewith using different arrangements of power extraction. .

As shown, when the planet gears 32 move in a planetary motion within the ring gear 31 on the housing frame, the planet gears 33 coaxially fixed with the gears 32 are also in the pairing of the second pair of ring gears and spur gears. Planetary motion is carried out in the ring gear 34. As the gear 33 rotates within the gear 34 and moves planetaryally, its outermost edge 33P (the pitch ring) draws a trajectory 33T. This trajectory 33T is arranged to exactly coincide with the pitch circle of the ring gear 34. That is, the ring gear 34 in the second set of matings, together with the spur gears 33 that are engaged with each other, produces a similar function to the off-axis power pick-up mechanism of the prior art cycloidal gear reducer but at the same time allows the invention to be more The speed conversion device produces a much larger speed conversion ratio.

Figure 4 is a schematic cross-sectional view showing a rotational speed conversion device in accordance with the present invention showing the dimensional relationships of the various components of the device of the present invention. The speed conversion device of the present invention has a pair of coaxial ring gears including a large ring gear 41 having a pitch diameter A and a small ring gear 44 having a pitch diameter D. The apparatus of the present invention further has a pair of coaxial spur gears including a large spur gear 42 having a pitch diameter B and a small spur gear 43 having a pitch diameter C. The large spur gear 42 is engaged with the large ring gear 41, and the small spur gear 43 is engaged with the small ring gear 44 to form two sets of tooth bite pairs. A carrier member 45E is coupled to the input shaft 45 of the conversion device. Planet carrier assembly 45E, which is a version of a "twisted short arm" of a conventional planetary carrier in a conventional planetary gear system, is paired with gears 42 and 43 in conjunction with input shaft 45 (located on the central axis 40 of the overall system) The central axis of its own axis 49 is formed.

In addition, the coaxial two gears 42 and 43 are fixed to each other to operate synchronously on the carrier 45E. In the example illustrated in Figure 4, the large ring gear 41 is fixed to the housing frame of the speed converting device as a reaction force component of the system, and the small ring gear 44 is coupled to the output shaft.

Among the speed conversion gear system devices, the four gears 41, 42, 43 and 44 satisfy the dimensional relationship of A = K + i, B = K, C = K - j and D = K + i - j. As will be understood by those skilled in the art, when gears are used to fabricate the speed conversion device embodying the present invention, the K, i and j dimension values should be set to integers.

The speed conversion device of Fig. 4 uses the carrier 45E as an input, the small ring gear 44 as an output, and the large ring wheel 41 as a reaction force member. The coaxial two spur gears 42 and 43 which are fixed to each other at this time perform planetary revolving motion in the system. The speed conversion ratio achieved by the speed conversion device of Fig. 4 is K(K + i - j) / ij. In such a speed conversion system constructed on the basis of gears, if the number of teeth is A=16T (tooth), B=15T, C=14T and D=15T, that is, K=15, i=1 and j=1, then its conversion The ratio is 225.

In contrast, the conventional cycloidal speed reducer (Fig. 1) has a speed conversion ratio of only -15 if its A = 16T and B = 15T. This means that under the same number of teeth, the speed conversion device of the present invention can achieve a speed conversion ratio of a square of the conventional cycloidal gear system.

The speed conversion device of the present invention can be applied to different speed conversion fabric applications according to the different input, output and reaction force components of the respective component gears and their planet carrier assemblies. The invention relates to a speed conversion device for general use, that is, for fixing the ring gear or the spur gear to provide a reaction force for use in deceleration or speed increase, the mechanism construction arrangement may have a pair of coaxial ring gears, It includes a large ring gear with a pitch diameter of A and a small ring gear with a pitch diameter of D. It also has a pair of coaxial spur gears, including a large spur gear having a pitch diameter of B and a small spur gear having a pitch diameter of C. The large spur gear meshes with the large ring gear teeth, and the small spur gear meshes with the small ring gear teeth to form two sets of tooth bite pairs. One of the planet carrier assemblies can be coupled to one of the input or output shafts of the device. One of the two pairs of coaxial pairs is paired with two gear trains that are fixed to each other for rotation on the planet carrier. One of the two pairs of coaxial pairs is fixed to the housing frame of the device and the other gear is coupled to the other of the input and output shafts of the device. In this speed conversion device, the four gears thereof must satisfy the dimensional relationship of A = K + i, B = K, C = K - j and D = K + i - j.

5 and 6 show cross sections of two speed conversion devices in accordance with the present invention, each having a different arrangement of input and output components. The examples in Figures 5 and 6 each show a speed reducer that utilizes two pairs of ring gears with different gear modules and a spur gear. In the two examples, the first pair of bite-matching large ring gears and large spur gears are both modulus 2 (ie, M2), 80-tooth ring gears 51 and 61, and have a pitch diameter of 160 mm, and both are 75T, M2 The spur gears 52 and 62 have a pitch diameter of 150 mm. The two pairs of the second pair of bite-fitted small ring gears and small spur gears are both 2.5- and 60-tooth ring gears 54 and 64 with a pitch diameter of 150 mm, and both are 56T, M2.5 spur gears. 53 and 63, the pitch diameter is 140 mm. Thus, when the assembly of Figure 5 has its large spur gear fixed to the housing frame of the shifting device system to provide a reaction force, the achieved reduction ratio is -224.

On the other hand, the configuration of the apparatus of Fig. 6 uses the same four gears as in Fig. 5, but the input, output and reaction force functions of the respective gears are the same as those described in Fig. 4. The large ring gear 61 is fixed to the casing frame 61F and is a reaction force member.

Note that the dimensions of the examples in Figures 5 and 6 are K = 15, i = 1, and j = 1.

In summary, the speed conversion device of the present invention, such as described in FIG. 4, may have four types listed in Table 1. Same speed conversion setting configuration. In the following Tables 1 and 2, R, O and I in each column respectively indicate the reaction forces of the respective rotating components of the apparatus of the present invention, and the output and input functions are assigned.

As will be understood by those skilled in the art, each of the deceleration fabrics in Table 1 can be easily transformed into a speed increasing fabric by simply changing the role designation of I and O.

Figure 7 is a schematic cross-sectional view showing a cross-section of a speed converting device in accordance with the present invention showing the dimensional relationships of the various components of the apparatus of the present invention for optimum speed-switching use in accordance with weight, size or power density. In this special state, the composition of the above list 1 becomes the following Table 2.

The rotation speed reduction ratio listed in the above two tables shows that the gear of the present invention can construct a reduction gear having a substantial reduction ratio of K ² using a gear having a K value of the center tooth number. This can be compared with the reduction ratio value K of the conventional conventional cycloidal gear reducer.

It is noted that, as will be understood by those skilled in the art, the spur gear (i.e., the external gear) that normally engages inside a ring gear must have a sufficiently small number of teeth than the number of teeth of the ring gear. For example, a common 20 degree pressure angle gear is usually required to have a difference in the number of teeth of 8 teeth or more. To use a smaller difference in the number of teeth in the system, a typical practice to avoid gear interference between the two gears is to profile shifting for the gears. Another approach is to use a larger pressure angle.

In addition, since the size of the two-coaxially paired planetary revolving components of the speed conversion device of the present invention is relatively close to the size of another coaxial pair that is separately engaged, it is actually only possible to use a pair of planetary revolving components. . Therefore, the use of a counterweight is necessary in the actual implementation of the conversion device of the present invention, i.e., the weight 65W depicted in a schematic manner in the embodiment of Fig. 6. This counterweight is utilized to balance the mass of the coaxial gear pair that deviates from the planetary revolution outside the rotationally symmetric central axis of the system.

Thus, a single-stage reduction gearbox of the aircraft engine to which the present invention is applied, such as the speed conversion device described in FIG. 4, can be coupled to the input speed of one of the input shafts of the turbine shaft of the aircraft engine for conversion to the aircraft engine. One of the fan shaft outputs the output speed of the shaft. The gearbox includes a pair of coaxial ring gears including a large ring gear having a pitch diameter of A and a small ring gear having a pitch diameter D. There is also a pair of coaxial spur gears, which include a large spur gear having a pitch diameter of B and a small spur gear having a pitch diameter of C. The large spur gear meshes with the large ring gear teeth, and the small spur gear meshes with the small ring gear teeth to form two sets of tooth bite pairs. There is also a planet carrier assembly that is coupled to the input shaft of the gearbox. Wherein, two of the two pairs of coaxial pairs are paired with each other to be fixed to each other for rotation on the planet carrier; one of the two pairs of coaxial pairs is fixed to the housing frame of the gearbox The other gear is coupled to the output shaft of the gearbox. The four gears satisfy the dimensional relationship of A=K+i, B=K, C=K-j and D=K+i-j, where K, i and j are integers.

When the invention is applied to an aerospace engine of a turboprop, its blade shaft can be its propeller shaft. When applied to an aerospace engine of a gear reduction turbine fan (GTF), its blade axis can be its low speed blade axis. If applied to an aero engine with an open rotor, its fan shaft can open its rotor shaft. When applied to a turboshaft aeroengine, its fanshaft can be its turbine shaft.

The invention has been described above by way of a preferred embodiment, and the above description is not intended to limit the invention. Anyone skilled in the art can make some changes and changes without departing from the spirit of the invention. Therefore, the scope of the invention is defined by the scope of the appended claims.

10, 30, 40, 50, 60, 70‧‧‧ system center axis

11,31,41,51,61,71‧‧‧large ring gear

12,32,42,52,62,72‧‧‧ Large spur gear

13,33,43,53,63,73‧‧‧Small spur gear

14,34,44,54,64,74‧‧‧ Small ring gear

15,35,45,55,65,75‧‧‧ input shaft

35E, 45E, 55E, 65E, 75E‧‧‧ planet carrier assembly

16,36,46,56,66,76‧‧‧ Output shaft

17,17C, 17G‧‧‧ round hole

18,18C,18G‧‧·roller

Figure 1 is a schematic view showing a conventional high-profile cycloidal speed reducer.

2 is a schematic view showing an off-axis power extraction coupling mechanism used in a conventional cycloidal speed reducer.

Figure 3 is a schematic cross-sectional view showing a single-stage, large-scale deceleration of a speed conversion device suitable for an aero engine, in accordance with the present invention, showing the configuration of an off-axis power take-up stage used in the apparatus of the present invention.

Figure 4 is a schematic cross-sectional view showing a single stage large scale reduction gearbox in accordance with the present invention showing the dimensional relationships of the various components of the apparatus of the present invention.

5 and 6 show cross sections of two speed conversion devices in accordance with the present invention, each having a different arrangement of input and output components.

Figure 7 is a schematic cross-sectional view showing a single stage large scale reduction gear unit in accordance with the present invention showing the dimensional relationships of the various components of the apparatus of the present invention for optimum speed conversion applications.

40‧‧‧System Center Axis

41‧‧‧ Large ring gear

42‧‧‧ Large spur gear

43‧‧‧Small spur gear

44‧‧‧Small ring gear

45‧‧‧ input shaft

45E‧‧‧Planet carrier assembly

46‧‧‧ Output shaft

Claims (10)

A single-stage reduction gearbox of an aero engine that converts an input speed of an input shaft coupled to a turbine shaft of an aero engine to an output speed of an output shaft coupled to an aero-engine engine shaft, the gearbox comprising: For a coaxial ring gear, it includes a large ring gear having a pitch diameter of A and a small ring gear having a pitch diameter D; a pair of coaxial spur gears including a large spur gear having a pitch diameter B and a pitch diameter C a small spur gear; the large spur gear meshes with the large ring gear teeth, and the small spur gear meshes with the small ring gear teeth to form a pair of tooth bite pairs; and a planet carrier assembly that is coupled to the input shaft of the gearbox; Two pairs of coaxial pairs are paired with two gear trains that are fixed to each other for rotation on the planet carrier; one of the two pairs of coaxial pairs is fixed to the housing frame of the gearbox, And the other gear is connected to the output shaft of the gearbox; and the four gears satisfy the dimensional relationship of A=K+i, B=K, C=Kj and D=K+ij, where K, i and j Is an integer. For example, the gearbox of claim 1 is wherein i and j are both less than 5. For example, the gearbox of claim 1 wherein K/i is less than 30/1 or K/j is less than 30/1. For example, the gearbox of claim 1 is where i equals j. A gearbox of claim 1 wherein one of the input and output shafts coupled to the planet carrier assembly is an input shaft. A gearbox of claim 1 wherein one of the input and output shafts coupled to the planet carrier assembly is an output shaft. A gearbox of claim 1 wherein the aircraft engine is a turboprop engine and the blade shaft is a propeller shaft of the turboprop engine. The gearbox of claim 1 wherein the aircraft engine is a gear reduction turbofan engine and The blade shaft is the low speed blade shaft of the gear reduction turbofan engine. A gearbox of claim 1 wherein the aircraft engine is an open rotor engine and the blade shaft is an open rotor shaft of the open rotor engine. A gearbox of claim 1 wherein the aircraft engine is a turboshaft engine and the blade shaft is the turbine shaft of the turboshaft engine.