JP2021502296A - System that supports rotor shafts - Google Patents

Abstract

The present invention relates to a system that supports the rotor shaft (1). The system comprises a rotor shaft (1) and a rolling bearing (5) having an inner ring (30). The rotor shaft (1) is shape-coupledly connected to the inner ring (30) of the rolling bearing (5). The first fixing element (41) fixes this shape-coupling connection in the axial direction. [Selection diagram] Fig. 4

Description

The present invention relates to a system that supports a rotor shaft. Furthermore, the present invention relates to a rotor shaft and an inner ring of a rolling bearing. Furthermore, the present invention relates to a method of manufacturing a rotor shaft and an inner ring. Furthermore, the present invention relates to a helicopter comprising a system that supports a rotor shaft.

The rotor shaft is typically connected at its lower end via a gearbox to a drive unit such as an internal combustion engine or turbine. The drive unit rotates the rotor shaft. The rotor hub is tightly connected to the rotor head at the upper end of the rotor shaft.

The helicopter's main gearbox typically comprises at least one input shaft, at least one tail rotor output shaft, and at least one rotor mast. Some helicopters do not have articulated rotor blades. In that case, forces such as bending, tension, shear, and vibration of the rotor blades are introduced directly into the rotor mast. The resulting load is absorbed by one or more rolling bearings in the rotor mast. Due to the high load on this type of helicopter, the rotor mast is also designed to be easily disassembled or removable.

Such rolling bearings may include, for example, an inner ring and an outer ring and must be axially fixed. In this case, especially in the aviation field, two construction methods are regularly considered. According to the first method, the rotor mast is usually fixed only with a mast nut located under the lower bearing. After loosening the mast nut, the rotor mast can be pulled upward from the bearing edge that receives the rotor mast and supports the upper bearing in particular, and defects in the rotor mast can be inspected in the framework of maintenance work. The basic configuration of the rotor mast is disclosed, for example, in German Registered Patent No. 199 44 412 C2. According to this method, individual inner rings are fixed by mast nuts or shaft nuts. The disadvantage of this method is that the threads create a significant notch effect, which adversely affects the load bearing capacity of the components. In that case, the rotor mast must be reinforced, which makes the rotor mast heavier.

According to the second method, the spacer tube is arranged between the lower bearing and the upper bearing. From the German Patent Application Publication No. 10 2012 203 178 A1, a power transmission device in which a spacer tube is arranged between upper and lower rolling bearings is known. The spacer tube comprises first and second longitudinal portions. The second longitudinal portion has higher bending elasticity than the first longitudinal portion. However, the spacer tube of this power transmission device is known to be expensive and laborious to manufacture.

From the German Patent Application Publication No. 10 2014 216 695 A1, spacer tubes for power transmission devices for rotorcraft are known. The spacer tube comprises a meandering cross-sectional shape and a plurality of interconnected straight truncated cone ring portions. The truncated cone ring portion comprises a base region and a top region.

The disadvantage of the second method is that the spacers or spacer tubes, or spacer bushes, tend to wear. This causes loss of pretension and can lead to damage to the gearbox.

German Registered Patent No. 199 44 412 C2 German Patent Application Publication No. 10 2012 203 178 A1 German Patent Application Publication No. 10 2014 216 695 A1

Therefore, an object of the present invention is to provide a system for bearing a rotor shaft, particularly a helicopter rotor shaft, which overcomes the drawbacks of the prior art. In particular, an object of the present invention is to provide a system that is structurally simple and cost-effective. A further aspect is to provide a rotor shaft for such a system and an inner ring of rolling bearings for such a system. A further aspect of the present invention is to provide a helicopter with such a system bearing a rotor shaft.

This object of the present invention is solved by the features described in independent claims 1 and 6. A favorable embodiment becomes apparent from the dependent claims.

Therefore, the present invention is based on a system that supports a rotor shaft.

According to the present invention, the system includes a rotor shaft, rolling bearings, and a first closing element. The rotor shaft is formally connected to the inner ring of the rolling bearing. The first fixing element fixes this shape-coupling connection in the axial direction.

Fixing or installing can mean both holding the position or state of a component and fixing the component. Axial fixation or fixation means that axial movement of the fixed component is prevented. This may mean that some play is allowed because the movement of the fixed components is limited to a particular region in the axial direction.

Rolling bearings in the form of ball bearings or cylindrical roller bearings are rolling bearings known per se. In rolling bearings, two mutually movable components, the so-called inner and outer rings, are separated by a rolling element or rolling element. During operation, these rolling elements roll between the inner and outer rings. This occurs on the hardened steel surface, the so-called orbit.

The rotor shaft and the inner ring are connected in a shape-coupling manner so as to prevent rotation in the circumferential direction.

It has been found that the present invention can provide a structurally simple and compact bearing fixing device, which is particularly cost-effective. Advantageously, according to the present invention, the notch effect when using shaft nuts, as well as the loss of pretension due to wear of the spacer tube when using the spacer tube that secures the bearing, can be caused. Both adverse effects are prevented. Moreover, there are no notches in the present invention. Therefore, the notch effect factor does not occur due to the fixed bearing structure of the inner ring.

In the first embodiment of the present invention, the inner ring and the rotor shaft are provided with grooves or recesses in the circumferential direction. The fixing elements engage these.

Preferably, the first fixing element is formed in a one-piece shape. For example, forming a fixing ring, splint, or other element of this kind, formed as a round wire snap ring, in a one-piece fashion that axially secures the shape-coupling connection between the rotor shaft and the inner ring. Can be done.

Further, preferably, the first fixing element is composed of at least two parts. The advantage of the first fixing element being composed of a plurality of parts is that it is easy to assemble. The multi-part fixing element is axially fixed but may fall out of the groove in the radial direction.

Further, preferably, the second fixing element fixes the first fixing element in the radial direction. The second fixing element may be, for example, a ring pressed onto the first fixing element. Fixation can be done directly, that is, in direct contact. Alternatively, fixing may be performed indirectly.

Further, preferably, the second fixing element serves an additional function in addition to the fixing, in particular as a running surface for additional components such as a radial shaft seal ring.

The second fixing element can also be used in combination with the one-piece type first fixing element.

Further, preferably, the system has the following features. The rotor shaft includes a plurality of first protrusions arranged along its circumference. The first protrusion extends radially outward from the rotor shaft. There is a first free space between the adjacent first protrusions.

The inner ring of the rolling bearing includes a plurality of second protrusions arranged so as to extend axially from the end face of the inner ring. There is a second free space between the adjacent second protrusions.

The first protrusion protrudes into the second free space. The second protrusion protrudes into the first free space. As a result, the first protrusions and the second protrusions are alternately adjacent to each other in the circumferential direction, so that rotation between the inner ring and the rotor shaft is prevented.

The first fixing element fixes the first protrusion and the second protrusion in a shape-coupling manner so that the axial displacement of the inner ring with respect to the rotor shaft is prevented.

The protrusion may be, for example, a protrusion or an extension in a component such as a rotor shaft or an inner ring. The extension may be molded into the corresponding component in a one-piece mold or may be molded in two parts. However, for manufacturing reasons, it is preferable that the components and the protrusions are one-piece, that is, form a single structural unit.

In the case of the inner ring, the convex portion can extend particularly axially. In the case of the rotor shaft, the convex portion can extend radially outward, especially in the radial direction, particularly starting from the surface of the rotor shaft.

The convex portion is sometimes referred to as a "tooth portion". The free space between the protrusions is also referred to as "between teeth".

Further, preferably, the first protrusion and the second protrusion have a U-shaped profile in cross section, and the first closing element has a T-shaped cross section corresponding to the U-shaped profile.

A further aspect of the invention provides a rotor shaft for a helicopter. The rotor shaft includes a plurality of first protrusions arranged along its circumference. The first protrusion extends radially from the rotor shaft. The protrusions are formed so as to receive the first fixing element in a shape-bound manner.

Further, preferably, in the rotor shaft, the protrusions that receive the first closing element in a shape-coupling manner each include a groove or a recess arranged along the circumference.

A further aspect of the invention provides an inner ring for rolling bearings. The inner ring includes a plurality of second protrusions arranged in the circumferential direction. The second protrusion extends axially from the end face of the inner ring. The protrusions are formed so as to receive the first fixing element in a shape-bound manner.

Preferably, the protrusions that receive the first closing element in a shape-coupling manner each include a groove or recess arranged along the circumference.

A further aspect of the present invention is to provide a method of manufacturing a rotor shaft. The method includes the following steps:

The method of manufacturing the rotor shaft includes a first step of providing a rotor shaft having a collar running in the circumferential direction, a second step of cutting a groove or a recess into the first protrusion, and a plurality of radially extending outward portions. 1 Includes a third step of milling the collar to manufacture the protrusions from the outer peripheral surface of the rotor shaft.

In terms of tool handling, it is easier to cut a groove into a continuous circumferential collar than to make a partial cut. Therefore, preferably, these three steps of manufacturing the rotor shaft can follow each other in chronological order. However, it is also possible to consider performing the third step before the second step.

A further aspect of the present invention is to provide a method of manufacturing an inner ring for a rolling bearing. The method is to manufacture an inner ring for rolling bearings, a first step to provide, a second step to cut a groove or recess into a second protrusion, and a plurality of axially extending second protrusions from the end faces of the inner ring. This includes a third step of milling the inner ring.

In terms of tool handling, it is easier to cut a groove into a continuous circumferential collar than to make a partial cut. Therefore, preferably, these three steps of manufacturing the inner ring can follow each other in chronological order. However, it is also possible to consider performing the third step before the second step.

A further aspect of the present invention is to provide a helicopter with the above-mentioned system bearing a rotor shaft.

According to the present invention, embodiments of the present invention, and further aspects of the present invention, one component, either the spacer tube or the thread of the nut, is omitted and there is no need to replace worn parts. Therefore, the present invention, embodiments of the present invention, and further aspects of the present invention are cost-effective, especially in mass production and maintenance of gearboxes. In addition, because the weight is reduced, the payload or maximum take-off weight (MOTW) can be increased. When the one-piece type first fixing element is used, the second fixing element can be omitted.

The present invention will be described in detail with reference to the following drawings.

It is a figure of the rolling bearing provided with the spacer tube which supports a rotor shaft by a prior art. It is a figure of the rotor shaft of 1st Embodiment by 1st aspect of this invention. It is a figure of the inner ring of the 1st Embodiment by 2nd aspect of this invention. It is a figure of the system which supports the rotor shaft of 1st Embodiment by a further aspect of this invention. It is a further view of the system of FIG. 4 with the first fixed element inserted. FIG. 5 is a diagram of the system of FIG. 5 with a second fixed element. It is a figure of the 2nd Embodiment of the system which supports a rotor shaft. It is sectional drawing in the longitudinal direction in the state which assembled the system of FIG. 4 to FIG. It is sectional drawing in the longitudinal direction in the state which assembled the system of FIG. It is a figure of a helicopter provided with a system which supports a rotor shaft.

FIG. 1 shows a conventionally known shaft 1 formed as a main rotor shaft of a helicopter. The shaft 1 is rotatably supported on the bearing package 11 on the left side and on the rolling bearing 5 on the right side. Seen in the axial direction, the bearing package constitutes the lower bearing and the rolling bearing 5 constitutes the upper bearing. The bearing package 11 includes a rolling bearing in the form of a cylindrical roller bearing 11a and a four-point bearing 11b.

A cylindrical roller bearing 11a fixed to a housing (not shown) by screw connection, in a manner known per se, has a rolling element having a cylindrical rolling element running radially between an inner ring and an outer ring, particularly between the inner ring and the outer ring. Includes moving body cages. The cylindrical roller bearing 11a has a large radial load bearing performance. However, the cylindrical roller bearing 11a cannot support only a small load or no load in the axial direction. The four-point bearing 11b is provided to absorb these forces.

The four-point bearing 11b is a single-row radial angular contact ball bearing in which a track is formed so that an axial load can be absorbed in both directions. The radial load only absorbs a fraction of the axial load. The four-point bearing 11b has a split inner ring and is not self-holding. Due to the split inner ring, multiple balls can be received in the bearing. As a result, relatively high load bearing performance can be obtained.

The upper rotor mast bearing 5 includes an inner ring 5a, an outer ring 5b, and a rolling element cage having a rolling element 5c arranged between the inner ring 5a and the outer ring 5b in the radial direction. The outer ring 5b is secured and attached to the housing (not shown) via a seal carrier or bush 3 using a screw connection. The raceway ring 2 and the shaft seal ring 4 are arranged between the shaft 1 and the seal carrier or the bush 3 in the radial direction. The raceway ring 2 rotates together with the shaft 1. The inner ring 5a includes two fixed rims 7 and 8. The rolling element 5c is guided onto the fixed rims 7 and 8.

The rolling bearing 5 is fixed to the right side in the axial direction by the interaction between the elements of the seal carrier 3, the shaft seal ring 4, and the raceway ring 2 and the shaft 1, and the inner ring 5a rotating in the load direction is It can be seen that in a normal press fit, it is not attached to the shaft 1.

The thumb shaft 17 transmits drive torques of two gear boxes (not shown) to the rotor shaft 1. Therefore, the thumb shaft 17 is inserted or clamped between the bearing package 11 and the rotor shaft 1 in a shape-coupling manner by the insertion connection portion or the clamp connection portion 17a.

A spacer tube 10 is provided in accordance with prior art to prevent or support the movement of the inner ring 5a during operation. The spacer tube 10 is arranged coaxially with the rotor shaft and holds the bearing package 11 at a position away from the rolling bearing 5 or the inner ring 5a. This secures the inner ring, and thus also the rolling bearing 5, against axial sliding to the left or down.

This previously known solution using spacer tubes is highly prone to wear. As a result, loss of pretension is caused, which can lead to damage to the gearbox.

FIG. 2 shows the rotor shaft 1 of the first embodiment of the present invention. The rotor shaft 1 has six first protrusions 21 running in the circumferential direction of the rotor shaft 1. Each of these protrusions 21 has a groove 22. There is a free space 23 between the protrusions 21 located adjacent to each other in the circumferential direction. The first protrusion 21 extends radially outward.

FIG. 3 shows the inner ring 30 of the rolling bearing 5 according to the first embodiment of the present invention. Except for the inner ring 30, the rolling bearing of FIG. 3 is the same as the rolling bearing of FIG. Therefore, the same code can be used.

The inner ring 30 includes six second protrusions 31 running in the circumferential direction. Each of these protrusions 31 has a second groove 32. There is a free space 33 between the protrusions 31 located adjacent to each other in the circumferential direction. The second protrusion 31 extends axially from the end face of the inner ring 30 to form a so-called axial protrusion.

The first protrusion 21 is milled from a collar running in the circumferential direction of the rotor shaft 20. Therefore, six protrusions 21 having the same size and evenly spaced are formed. The second protrusion 31 is milled on the inner ring 30. Therefore, six protrusions 31 having the same size and at equal intervals are formed. The first groove 22 and the second groove 32 are notched.

The number of protrusions can be changed. 3, 4, 5, 7, 8, or 9 protrusions can also be configured. The number is particularly preferably 6, 7, or 8. Usually, the protrusions have manufacturing variations. Therefore, the dimensions are not the same. It has been found that with 6, 7, or 8 protrusions, the circumferential surface pressure between adjacent protrusions can be optimally reduced, thereby reducing the occurrence of wear in an advantageous manner. It was.

It is also possible to consider changing the spacing between adjacent protrusions. The equal size of the protrusions and the equal spacing has the advantage of being easier to assemble.

The first protrusion 21 corresponds to the second protrusion 31. Similarly, the first groove 22 and the second groove 32 correspond to each other. That is, in the assembled or assembled state, the first protrusion 21 engages with the second free space 33, and the second protrusion 31 engages with the first free space 23. On the other hand, the first groove 22 and the second groove 32 form a common circumferential groove.

FIG. 4 is a view of the system 100 that supports the rotor shaft, and is a partial view at the time of assembling the rolling bearing 5 including the inner ring 30 and the rotor shaft 1. The inner ring 30 is oriented with respect to the rotor shaft 1 so that the inner ring 30 can be pushed into the first free space 23 by the second protrusion 31.

FIG. 4 further shows a fixed element 40 in the form of a split ring. The dividing ring is an example of a first fixed element composed of a plurality of parts. The dividing ring 41 constitutes a complementary portion to the grooves 22 and 32 and can be engaged with the grooves 22 and 32. Further, FIG. 4 shows a second fixed element 42. The split ring 41 is not fixed in the radial direction and may fall off. Therefore, in this case, the second fixing element 42 is required. Advantageously, the second fixing element 42 also functions as a raceway ring for the radial shaft seal ring 43 of the radial shaft (not shown). The support tube 44 can be screwed to the outer ring 5b and the housing 45. The split ring can be manufactured, for example, by splitting a cylindrical component with a collar running inward in the radial direction into two equally sized portions, or halflings.

FIG. 5 is a cross-sectional view of a rolling bearing 5 including an inner ring 30, a rotor shaft 1, and a dividing ring 41. The second protrusion of the inner ring 30 and the split ring 41 that engages with the second protrusion can be clearly recognized. For this purpose, the protrusion 31 of the inner ring 30 and the protrusion (not shown) of the rotor shaft 1 have a rectangular U-shaped profile in cross section. The split ring 41 has a corresponding F-shaped profile. However, the T-shaped profile of the split ring 41 may also be considered. The seal quality of the inner ring may be reduced by the gaps created between the individual protrusions. The F-shaped profile (also known as the double ring) improves shape-connecting connections. Further, since the F-shaped profile covers the first and second protrusions flatly in the axial direction, subsequent sealing is easy. The sealing can be performed so that the rotor shaft 1, the dividing ring 41, and the raceway ring 42 are sealed by, for example, a rubber compound.

In addition to FIG. 5, FIG. 6 shows a second fixing element 42. The second fixing element 42 also functions as a raceway ring of the radial shaft seal ring 43. The raceway ring 42 fixes the dividing ring 41 in the radial direction. The L-shaped profile of the raceway ring 42 additionally functions to be axially fixed and sealed. The radial shaft seal ring 43 runs on the radial back surface of the raceway ring 42. The axial gap between the end face of the inner ring 30 and the raceway ring 42 functions to engage the tool to remove the raceway ring.

Unlike FIGS. 5 and 6, FIG. 7 shows a one-piece first fixing element 41 in the form of a round wire snap ring. Since the first fixing element 41 does not fall from the grooves 22 and 32 in the radial direction, it is sufficient to fix the shape coupling in the axial direction. A sealing element with an L-shaped cross section is provided to better seal the protrusions. This seal element is arranged between the protrusions 21 and 31 and the raceway ring 42 in the radial direction. The seal element 41a does not engage the grooves 22 and 32. Compared to the system according to FIG. 6, in the system according to FIG. 6, the dividing ring engages the groove and also seals. Therefore, according to FIG. 7, at least one additional component is required.

FIG. 8 shows a preferred first embodiment rotor shaft bearing system in a longitudinal sectional view in an assembled state.

The rolling bearing 5 including the inner ring 30, the rolling element cage 5c, and the outer ring 5b is pressed against the rotor shaft 1. The rolling element cage 5c is located between the inner ring 30 and the outer ring 5b in the radial direction. The fixing element 41 composed of two parts is a T-shaped part of the F-shaped profile, engages with the grooves 22 and 32 of the first protrusion 21 and the second protrusion 31, and the protrusion 21 at its end face. Surround 31. The ring 41 composed of two parts is fixed in the radial direction by using the ring 42. The ring 42 also functions as a raceway ring for the radial shaft seal ring 43. The support tube 44 is screwed to the outer ring and the housing.

FIG. 9 shows a longitudinal sectional view of a system bearing a rotor shaft of a preferred further embodiment in an assembled state.

Unlike FIG. 8, the first fixing means 41 is a round wire snap ring. Therefore, the raceway rings are not additionally formed to engage the grooves 21, 31 in a shape-coupling manner and therefore do not have a T-shaped profile.

FIG. 10 shows a helicopter with a system 100 bearing a rotor shaft. The system 100 can be used in the helicopter 80 for the main rotor gearbox 50, the tail rotor gearbox 60, and / or the deflection gearbox 70.

1 Shaft, Rotor shaft 2 Track ring 3 Seal carrier, Bush 4 Shaft seal ring 5 Roller bearing, Cylindrical roller bearing 5a Inner ring 5b Outer ring 5c Roller, Roller cage 6 Connection means, Screw connection 7 1st rim 8 2nd rim 9 3rd rim 10 Spacer tube, Spacer 11 Bearing package 11a Cylindrical roller bearing 11b Four-point bearing 12 Shaft nut 13 Steel ring 14 Gear outlet zone 15 Nose 16 Means, Contact area 17 Thumb shaft 17a Shape coupling connecting means, plug-in arm, Clip arm
21 1st protrusion, convex part, tooth part 22 1st groove, concave part 23 1st free space, blank 30 Inner ring 31 2nd protrusion, convex part, tooth part 32 2nd groove, concave part 33 2nd free space, blank 41 First fixing element, one-piece type / round wire snap ring consisting of multiple parts, fixing ring, splint, split ring 41a Seal element 42 Second fixing element, ring, raceway ring 43 Radial shaft seal ring 44 Support tube 45 Housing 50 Main rotor gear box 60 Tail rotor gear box 70 Deflection gear box 80 Helicopter 100 Rotor shaft bearing system

Claims (6)

A system that supports a rotor shaft (1), including a rotor shaft (1) and a rolling bearing (5) having an inner ring (30).
The rotor shaft (1) includes a plurality of first protrusions (21) along the circumference of the rotor shaft (1), and the first protrusion (21) has a diameter from the rotor shaft (1). There is a first free space (23) between the first protrusions (21) extending outward in the direction and adjacent to the first protrusion (21).
The inner ring (30) includes a plurality of second protrusions (31) extending axially from the end surface of the inner ring (30), and a second protrusion (31) is provided between the adjacent second protrusions (31). There is free space (33),
The first protrusion (21) and the second protrusion (31) are alternately adjacent to each other in the circumferential direction so that rotation between the inner ring (30) and the rotor shaft (1) is prevented. The first protrusion (21) protrudes into the second free space (33), and the second protrusion (31) protrudes into the first free space (23).
The first fixing element (41) causes the first protrusion (21) and the second protrusion (31) to be prevented from being displaced in the axial direction of the inner ring (30) with respect to the rotor shaft (1). A system (1) that is fixed in a shape-bound manner. The system according to claim 1, wherein the inner ring (30) and the rotor shaft (1) are provided with a first groove or recess (22) in the circumferential direction, and the first fixing element (41) is the same. A system that engages in a first groove or recess (22). The system according to claim 1 or 2, wherein the first fixing element (41) is made of a one-piece type. The system according to any one of claims 1 to 3, wherein the first fixing element (41) is composed of at least two parts. The system according to any one of claims 1 to 4, wherein the second fixing element (42) fixes the first fixing element (41) in the radial direction. A helicopter comprising a system that supports the rotor shaft (1) according to any one of claims 1 to 5.

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