JP3102777B2 - Shimmy damper device for aircraft nose landing gear - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a shimmy damper device for an aircraft nose gear provided on a steering rotation portion of a nose gear in order to prevent shimmy from occurring during taxiing of an aircraft.

[0002]

2. Description of the Related Art In various small aircraft, a strut piston for supporting a wheel is inserted into a strut cylinder, which is a pillar of a front leg, and a steering actuator for rotating the strut piston about its axis is inserted into the strut cylinder. And a steering collar connected to the strut piston by a torque link is mounted.

[0003] Such an aircraft nose gear is provided with a shimmy damper device for generating Coulomb frictional force between the steering collar and the strut cylinder to attenuate shimmy.

FIG. 4 shows a steering pivot 1 in which a typical prior art aircraft nose gear shimmy damper device is implemented.
It is sectional drawing of a vicinity. In the steering rotation unit 1, a strut piston 3 that supports a wheel is inserted into a strut cylinder 2 of the front leg of the aircraft, and the strut piston 3 is rotated around its axis 4 on the outer periphery of the strut cylinder 2. (Not shown) and a steering collar 5 connected to the strut piston 3 by a torque link (not shown) are mounted. Grease is sealed in the steering collar 5 so that the steering collar 5 and the strut cylinder 2 It is configured to lubricate the space.

[0005] The strut piston 3 is slidably inserted in the direction of the axis 4 into the strut cylinder 2, and the strut piston 3 is retained by a retaining nut 10. The steering rotating portion 1 of the strut cylinder 2 has a thick portion 11, and the thick portion 11 has a pair of straight cylindrical lands 12a and 12b into which the steering collar 5 is rotatably fitted. An annular concave groove 13 formed between the lands 12a and 12b, and an annular rising part 15 having a stepped surface 14 which rises at a right angle from the base end of the strut cylinder 2, that is, the land 12a on the upper side in FIG.
And

[0006] The steering collar 5 is provided on each land 12.
a, a pair of inner rings 16a, 16b mounted on the 12b
And an annular outer ring 17 extrapolated to each of the inner rings 16a, 16b.
And Each inner ring 16a, 16b is
a and 12b are spaced apart in the direction of the axis 4 with an interval ΔL1. By such an interval ΔL1, each inner ring 1
Via an annular passage 18 formed between 6a and 16b,
The grease stored in the concave groove 13 is supplied between the inner peripheral surface of the outer ring 17 and the outer peripheral surfaces of the inner rings 16a and 16b.

[0007] Of the inner rings 16a, 16b, one of the inner rings 16b, which is located closer to the free end of the strut cylinder 2, that is, located below in FIG. 4, is supported by a pressing ring 19, which is connected via a disc spring 21. The strut cylinder 2 is supported by a spring receiving ring 22 externally inserted into the outer cylinder 6. A bolt 24 attached to the bent piece 23 of the retaining nut 10 screwed to the sleeve 9 is screwed into the spring receiving ring 22 to prevent the spring receiving ring 22 from being removed.

The grease in the groove 13 is guided through the passage 18 between the inner peripheral surface of the outer race 17 and the outer peripheral surfaces of the inner races 16a and 16b, as described above.
4 between the inner peripheral surfaces of the inner rings 6a and 16b and the outer peripheral surfaces of the lands 12a and 12b and the end surface of the other inner ring 16a and the stepped surface 1 of the rising portion 15 closer to the base end disposed further upward in FIG.
4 and between the end face of one inner ring 16b and one surface of the pressing ring 19 facing the one inner ring 16b.

In this way, the damping torque is generated in a boundary friction state where the solid contact and the supporting force of the grease by the pressure of the liquid are mixed.

A damper utilizing such Coulomb friction force has a very simple structure, and generates a large damping force with a small amplitude as a characteristic. However, in the case of large amplitude, there is a problem that the damping force against shimmy is relatively insufficient because the Coulomb friction force is constant.

Further, a lubricant such as grease is required for a sliding surface between the steering collar and the outer cylinder. A boundary friction state caused by such a lubricant such as grease, that is, solid contact and liquid In a state where the supporting force due to the pressure is mixed, the frictional force in the operating state becomes unstable, and stable performance cannot be exhibited.

In another conventional technique, a shimmy damper utilizing the shearing force of a viscous oil is used in, for example, a helicopter. However, in such a viscous damper, the viscous friction characteristic is small at a small amplitude as a characteristic of the viscous friction. Therefore, in order to suppress the small amplitude vibration that occurs within the range of steering rattling, the configuration becomes considerably large. Problem.

In another prior art, it is also known to provide an orifice in an oil passage in a steering actuator so that the actuator also functions as a damper. However, if the accuracy during operation of the actuator is improved, the function of the damper is relatively increased. Are restricted, so that each cannot be designed optimally. In addition, there is a problem that the effect of the damper is reduced with respect to vibration of small amplitude due to backlash in the connection between the actuator and the steering collar.

[0014]

SUMMARY OF THE INVENTION It is an object of the present invention to provide an aircraft nose gear capable of stably attenuating vibration caused by shimmy from small amplitude to large amplitude without largely changing the structure of a steering rotating portion. Is to provide a more compact shimmy damper device.

[0015]

According to a first aspect of the present invention, there is provided a fixing member fixed to a fuselage side of an aircraft nose landing gear, and a fixing member rotatably mounted on an axis of a pedestal, the wheel moving direction. And a viscous oil sealed in a space formed between the fixed member and the rotating member. The fixed member and the rotating member resiliently A shimmy damper device for an aircraft nose gear, wherein Coulomb friction is generated upon contact, vibration of small amplitude of the rotating member is attenuated by Coulomb friction, and vibration of large amplitude of the rotating member is attenuated by viscous oil. It is.

According to the present invention, since the rotating member is rotated in accordance with the steering in the traveling direction of the wheel, when the shimming occurs, the rotating member vibrates around the axis of the pillar with respect to the fixed member. The rotating member and the fixed member come into contact with each other to generate Coulomb friction, and viscous oil is sealed in a space between the rotating member and the fixed member. Damped by frictional force. In particular, since the Coulomb friction force generates a large damping torque even with a small amplitude, small-amplitude vibration occurring within the range of steering rattling can be sufficiently suppressed. Further, since the viscous friction due to the viscous oil has a characteristic that the damping torque increases as the steering angular velocity increases, the large amplitude of the rotating member is attenuated by the viscous friction force due to the viscous oil. As described above, by using the Coulomb friction force and the viscous friction force together, it is possible to attenuate shimmy ranging from a small amplitude to a large amplitude. Further, since the vibration of small amplitude is attenuated by the Coulomb friction force, it is not necessary to suppress the vibration of small amplitude by viscous friction. It is possible to damp vibrations over amplitudes.

According to a second aspect of the present invention, a solid lubricant is interposed at a contact portion between the fixed member and the rotating member.

According to the present invention, since a solid lubricant is interposed, a liquid lubricant such as grease is not required. Therefore, it is possible to prevent a boundary friction state in which the solid contact and the support force due to the liquid pressure intersect at the time of generation of vibration, so that the Coulomb friction force can be applied stably to attenuate the vibration. In addition, since a fluid lubricant such as grease is not required, it is not necessary to provide a structure for avoiding confusion between the viscous oil and the lubricant, and the shimmy damper device can be downsized.

[0019]

FIG. 1 is a sectional view showing the vicinity of a steering rotating portion 31 showing a shimmy damper device for an aircraft nose landing gear according to an embodiment of the present invention. FIG. 2 is a sectional view showing the steering rotating portion shown in FIG. FIG. 2 is a perspective view showing a front leg 32 of the aircraft including a part 31. The front leg 32 of the small aircraft has a pillar composed of a strut cylinder 33 and a strut piston 34, and a strut piston 34 is inserted into the strut cylinder 33 connected to the fuselage side. Is provided with a steering rotating portion 31 that rotates around its axis 35.

The steering rotating portion 31 includes a steering collar 38 which is a rotating member rotatably mounted on the strut cylinder 33, a torque link 37 provided from the steering collar 38 to the strut piston 34, and a torque link 37. A steering actuator 36 for steering the strut piston 34 through the steering wheel is provided.

In the enlarged diameter portion 44 of the strut cylinder 33,
The stator 45 is extrapolated and fixed. A support member 29 that supports the steering collar 38 is fixed to the free end of the strut cylinder 33. The stator 45 and the support member 29 fixed to the strut cylinder 33 function as a fixing member. A steering collar 38 functioning as a rotating member is mounted on the stator 45 so as to be rotatable around the axis 35 while being supported by the support member 29.

The enlarged diameter portion 44 of the strut cylinder 33
1 has a rising portion 46 protruding radially outward in the upper part of FIG. 1. The rising portion 46 faces the lower part of FIG. 1 and is formed in an imaginary plane perpendicular to the axis 35. It has an annular step surface 47 to be formed. An annular first solid lubricant 48 is disposed on the step surface 47.

The stator 45 includes a strut cylinder 33
A substantially cylindrical portion 51 extending along the outer peripheral surface of the enlarged diameter portion 44, a ridge portion 52 projecting radially outward from an intermediate portion between both ends in the axial direction of the cylindrical portion 51, Part 51
1, that is, a first cylindrical portion 53 having a straight cylindrical shape extending coaxially from the lower end in FIG. 1, and coaxial from the other axial end of the cylindrical portion 51, that is, from the upper end in FIG. 1. And a second small-diameter cylindrical portion 54 extending in a straight cylindrical shape. Such a stator 45 is surrounded by the steering collar 38.

The steering collar 38 is provided on the collar body 5.
5 and a retaining ring 56 attached to the lower portion of the collar body 55. The inner peripheral surface of the collar body 55 is
Cylindrical first to fourth inner peripheral surfaces 57 having a common axis
a to 57d and first to third step surfaces 58a to 58c. The outer periphery of the collar body 55 has a projection 63 projecting radially outward from a part in the circumferential direction, into which the connection pin 61 and the sleeve 62 of the torque link 37 are inserted.

When the retaining ring 56 is mounted on the collar body 55, the region of the end face 66 near the outer peripheral portion abuts on the second step surface 58b.
An annular fitting groove 67 into which the ridge 52 of the stator 45 is fitted is formed by the step surface 58a, a region facing the first step surface 58a, and the second inner peripheral surface 57b.
In a state where the ridge 52 of the stator 45 is fitted in the fitting groove 67, the first stepped surface 58 a and the second inner peripheral surface 57 are formed.
b and a region of the end surface 66 of the retaining ring 56 facing the first step surface 58a and an outer surface of the ridge portion 52 are spaced apart from each other by a distance ΔL2, thereby forming a substantially U-shaped space. 68 are formed over the entire circumference. The space 68 is formed between the outer space and the annular first seal member 69 fitted on the inner periphery of the collar body 55 and the annular second seal member 70 fitted on the inner periphery of the retaining ring 56. Partitioned liquid tight. High-viscosity silicone oil is sealed in such a space 68.

The collar body 55 is provided with a viscous oil supply means 71 for supplying the high-viscosity silicone oil into the gap 68 at a predetermined supply pressure. The viscous oil supply means 71 protrudes from the outer peripheral portion of the collar body 55 in one radial direction and has a piston chamber 72 having a piston chamber 72 opened on the second inner peripheral surface 57b.
Are housed in a spring 74 which is screwed into an oil supply cylinder 73 to close the oil supply piston chamber 72 from the outside in the radial direction of the collar body 55, and a spring storage recess 76 formed in the cap 75. , The piston 74
And a compression coil spring 77 that resiliently presses in a direction approaching the stator 45.

With this configuration, the piston chamber 72
The high-viscosity silicone oil stored in the piston 75
Thus, the high-viscosity oil is always filled in the gap 68 following the consumption of the high-viscosity silicone oil in the gap 68 and the volume change of the high-viscosity silicon oil due to the temperature change. State can be maintained.

A first seal member 69 is attached to the inner peripheral portion of the collar body 55 to prevent the high-viscosity silicone oil in the gap 68 from leaking to the first solid lubricant 48 side.
Similarly, a second seal member 70 is mounted on the inner peripheral portion of the retaining ring 56, and a third seal member 7 is mounted on the outer peripheral portion.
8 is attached. These second and third seal members 7
0, 78, the retaining ring 56 and the collar body 55
Is achieved, and leakage of the highly viscous silicone oil in the gap 68 is prevented.

The strut cylinder 33 and the strut piston 34 have upper portions (not shown) of an oleo-buffer support structure, which are configured to be able to reduce the impact in the direction of the axis 35 during takeoff and landing and taxiing. This oleo buffer strut structure is a so-called oil damper structure, and the strut piston 3
4 is filled with hydraulic oil. In order to prevent leakage of the hydraulic oil, the strut cylinder 3
An annular fourth seal member 79 is fitted to the inner periphery of the third seal member 79. The fourth seal member 79 achieves liquid tightness between the outer peripheral surface of the strut piston 34 and the inner peripheral surface of the strut cylinder 33, and the hydraulic oil displaces the strut piston 34 in the direction of the axis 35 and the axis 35. Leakage is prevented by rotation around.

The retaining ring 56 includes a second and a third
A base 81 to which the seal members 70 and 78 are fitted;
One axial end portion, that is, a straight cylindrical cylindrical portion 82 coaxially extending from the outer peripheral portion of the lower end portion in FIG. The cylinder 82 is fixed to the collar body 55 by bolts 83. As a result, the retaining ring 56 is attached to the collar body 55.
Are connected to each other in a state where displacement in the direction of the axis 35 and angular displacement around the axis 35 are prevented, and can rotate around the axis 45 around the stator 45 integrally with the collar body 55.

A support member 29 is provided below the base 81 of the retaining ring 56 in FIG. The support member 29 has a spring receiving ring 87, a disc spring 86, and a sliding ring 85. The sliding ring 85 contacts an end surface 84 facing the lower side of the retaining ring 81. The slide ring 85 is elastically pressed by a disc spring 86 in a direction approaching the end face 84. The disc spring 86 is supported by a spring receiving ring 87. A retaining ring 88 is mounted on the outer peripheral portion of the spring receiving ring 87, and the retaining ring 88 is supported by a support piece 89 bent substantially in an L shape. The support piece 89 is fixed to a nut 91 by a bolt 90, and the nut 91 is screwed to an external thread portion engraved on the outer peripheral portion of the outer cylinder 40.

The sliding ring 85 has a thin annular metal ring main body 92 and a second solid lubricant 93 fixed to one surface of the ring main body 92. Second solid lubricant 9
Reference numeral 3 denotes a structure similar to that of the above-described first solid lubricant, which is elastically pressed against the end surface 84 of the retaining ring 56 by the disc spring 86, and the retaining ring 56 is
When rotated together with the first solid lubricant 48, a Coulomb friction force is generated.

FIG. 3 is a graph showing the relationship between the steering angular velocity and the damping torque. In FIG. 3, a line L1 indicated by a dashed line indicates a damping torque characteristic of a conventional friction damper, a line L2 indicated by a broken line indicates a damping torque characteristic of a conventional large viscous damper, and a line L3 indicated by a solid line indicates friction. 4 is a graph showing damping torque characteristics of a shimmy damper device of the present invention including a damper and a viscous damper.

Since static friction is generated in the friction damper using Coulomb friction, as shown by reference numeral P in FIG. 3, the damping torque shows a maximum value that becomes the maximum static friction torque immediately before the steering angular displacement. . Further, the conventional friction damper requires a fluid lubricant such as grease, and as a result, as shown by a line L1, the damping torque sharply decreases immediately after the steering angular displacement, and thereafter, the damping torque decreases regardless of the steering angular velocity. It will be constant.

In the damping torque characteristic of the viscous damper, the damping torque increases in proportion to the increase of the steering angular velocity. Therefore, when the steering angular velocity is small and the amplitude is small, sufficient damping torque cannot be obtained. In order to solve such a problem, conventionally, the line L2
As shown in (1), it is necessary to increase the damping coefficient due to viscosity, that is, to increase the slope of the graph. By increasing the damping coefficient in this manner, the configuration of the conventional viscous damper becomes large.

In contrast to such a conventional damper, the present invention uses a viscous damper and a friction damper in combination, so that the damping torque characteristic of the present invention is substantially as shown by the line L3. This is a graph in which the damping torque characteristics of the viscous damper are added to the damping torque characteristics. Furthermore, unlike the conventional friction damper, the friction damper of the present invention uses a solid lubricant, so that the difference between the maximum static friction torque and the dynamic friction torque can be reduced. In addition, since lubricating agents such as grease are not required as in the past, the damping torque becomes unstable due to an increase in the steering angular velocity. That is, the damping torque shows a value substantially equal to the maximum static friction torque regardless of the steering angular velocity.

When the steering angular velocity is small and the amplitude is small, the vibration is attenuated by the damping torque of the friction damper of the shimmy damper device of the present invention. do not do. Therefore, it is not necessary to increase the damping coefficient of the viscous damper portion, and the size of the shimmy damper device can be reduced.

A large damping torque is required to attenuate the large amplitude at which the steering angular velocity increases. As shown by the line L3, in the present invention, as the steering angular velocity increases due to the action of the viscous damper, the damping torque also increases. Since it increases, even a large amplitude can be attenuated by the shimmy damper device of the present invention.

The inventor of the present invention has found from the experimental results that the combined use of viscous friction and Coulomb friction can provide a large damping force from a small amplitude to a large amplitude regardless of the value of the viscosity coefficient and the value of the Coulomb friction force. It was confirmed that the fluctuation of the frictional force from the static frictional force to the dynamic frictional force was small, and that the vibration caused by the shimmy could be damped with a simple configuration without increasing the static frictional force.

[0040]

According to the first aspect of the present invention, damping torque due to viscous oil sealed between the fixed member and the rotating member and Coulomb frictional force at which the fixed member and the rotating member come into contact with each other. Thus, the vibration caused by the shimmy of the aircraft nose gear is damped. In particular, small amplitude vibrations due to shimmy are attenuated by Coulomb frictional force, and large amplitude vibrations are attenuated by viscous frictional force, so that vibrations from small to large amplitudes can be attenuated. Further, since the vibration at the time of the small amplitude is attenuated by the Coulomb friction force, it is not necessary to increase the viscous friction force, so that the size of the shimmy damper device can be reduced.

According to the second aspect of the present invention, since a solid lubricant is interposed at a contact portion between the fixed member and the rotating member, fluid lubrication such as grease is not required. This eliminates the problem that the damping torque suddenly decreases due to an increase in the steering angular velocity, and allows the Coulomb friction force to act stably. Further, since it is not necessary to provide a structure for avoiding confusion between the viscous oil and a fluid lubricant such as grease, the size of the configuration can be reduced.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view of the vicinity of a steering turning section 31 showing a shimmy damper device for an aircraft front leg according to an embodiment of the present invention.

FIG. 2 is a perspective view showing a front leg 32 of the aircraft including the steering rotation unit 31 shown in FIG.

FIG. 3 is a graph showing a relationship between a steering angular velocity and a damping torque.

FIG. 4 is a cross-sectional view of the vicinity of a steering rotation unit 1 in which a typical prior art aircraft front leg shimmy damper device is implemented.

[Explanation of symbols]

 29 Support Member 31 Steering Rotating Part 32 Front Leg 33 Strut Cylinder 34 Strut Piston 36 Steering Actuator 37 Torque Link 38 Steering Collar 45 Stator 48 First Solid Lubricant 51 Cylindrical Part 52 Protrusion 55 Color Body 56 Retaining Ring 69, 70 , 78, 79 Sealing member 71 Viscous oil supply means 86 Disc spring 87 Spring receiving ring 88 Retaining ring 89 Supporting ring 93 Second solid lubricant

────────────────────────────────────────────────── 56 Continuation of the front page (56) References US Pat. No. 2,589,341 (US, A) US Pat. No. 4,265,417 (US, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) B64C 25/50

Claims (2)

(57) [Claims] A fixed member fixed to the fuselage side of an aircraft nose gear; a rotating member mounted on the fixed member so as to be rotatable around an axis of a pedestal, and rotated with steering in a wheel traveling direction; A viscous oil sealed in a space formed between the fixed member and the rotating member, wherein the fixed member and the rotating member elastically come into contact with each other to generate Coulomb friction, A shimmy damper device for an aircraft nose gear, wherein vibration of small amplitude is attenuated by Coulomb friction, and vibration of large amplitude of the rotating member is attenuated by viscous oil. 2. The shimmy damper device for an aircraft nose gear according to claim 1, wherein a solid lubricant is interposed at a contact portion between the fixed member and the rotating member.