JPS621211B2 - - Google Patents

Description

[Detailed Description of the Invention] Purpose of the Invention (Field of Industrial Application) The present invention provides a fluid coupling with many degrees of freedom, particularly in wind tunnel experiments, by reducing the force associated with the rigidity of high-pressure air piping and making it easier to install the piping system. The present invention relates to a fluid coupling suitable for use as an eccentric journal air coupling that can improve the measurement accuracy of aerodynamic forces.

(Prior Art) When conducting powered model tests of aircraft in a wind tunnel, a jet of high pressure air is often used to simulate a jet engine. The force and rotational moment acting on the model are measured with a balance. However, what the balance measures at this time is the resultant force of the air force and the force associated with the rigidity of the high-pressure air supply piping. This force associated with the rigidity of the piping (hereinafter referred to as piping interference force) often reaches several times the aerodynamic force. Therefore, in order to improve the measurement accuracy of aerodynamic force, it is important to reduce the piping interference force with respect to the resultant force measured by the balance and to relatively increase the proportion of aerodynamic force.

As a method of reducing such piping interference force, as shown in FIG. There are some methods that try to reduce the interference force (for example, AIAA
Aero-dynamic Testing Conference Washington
J. Williams, SFJ in DC March 1964
Butler's report). In this method, the rigidity of the pipe 2 increases in proportion to the supply air pressure, increasing the pipe interference force, and it is impossible to reduce the pipe interference force when the supply air pressure is high, making it difficult to reproduce the pipe interference force. Moreover, it has the disadvantage that it is impossible to organize the piping system into a compact size.

There is also a method that attempts to minimize some components of piping interference force by using air joints that utilize the principle of air bearings (for example, TRANS
- ACTIONS OF THE ASME January 1957, pp. 11-21).

The journal type air joint shown in FIG. 2 has a total of two degrees of freedom, one translational movement and one rotational movement. Lateral movement commensurate with the width of the groove 6 is performed under the bearing action of the high-pressure air flow flowing through the gap 7 between the pipe 4 and the joint portion 5.

The thrust type air joint shown in Fig. 3 has a total of three degrees of freedom: two translational movements and one rotational movement.
A translational movement of the joint part 5 is allowed by the difference between the inner circumference of the pipe 4 and the outer diameter of the extension part 8 of the pipe 4.

The ball type air joint of FIG. 4 has three rotational degrees of freedom. That is, the joint part is ball-shaped,
The coupling is capable of rotation about the axis of the outlet pipe 9 as well as rotation with an axis perpendicular to the axis of the pipe 4 to the extent permitted by the opening 11 in the shell 10 of the ball.

Compared to the journal type shown in Figure 2, the thrust type shown in Figure 3 has a flat joint contact surface, making it difficult to create a uniform air layer, and in both types the outlet pipe is relative to the inlet pipe. It will face at right angles. . In the ball type shown in Fig. 4, it is difficult to finish the spherical surface with high precision. The journal type shown in FIG. 2 is relatively easy to manufacture, but it has the disadvantage that it has a small degree of freedom of movement and there are few piping interference force components that can be reduced.

(Problems to be Solved by the Invention) When using air joints to reduce pipe interference forces in wind tunnel experiments, it is necessary to install air joints between the model and the air supply piping; Since the relative positions of the air supply piping are fixed and constrained by the balance, it is possible to install the air joint between the model and the air supply piping while maintaining the narrow gap between the air bearings, which is a conventional method of freedom. This is not an easy task for air fittings with a small amount of air.

The present invention aims to provide a fluid coupling with many degrees of freedom without the above-mentioned drawbacks by combining eccentric shafts.

Structure of the Invention (Means for Solving Problems) In this invention, the structure of the fluid coupling is composed of a bearing base, an outer floating shaft, an inner floating shaft, and a shaft cylinder, and the outer floating shaft and the inner floating shaft are Each has an inner cylindrical wall that is eccentric to the outer cylindrical wall, the shaft cylinder is located within the cylindrical inner wall of the inner floating shaft, the inner floating shaft is located within the cylindrical inner wall of the outer floating shaft, and the outer floating shaft is located within the cylindrical inner wall of the bearing base. The bearing base and the outer floating shaft, the outer floating shaft and the inner floating shaft, and the inner floating shaft and the shaft cylinder are arranged to be rotatably inserted and held in each of the inner and outer cylinders, and at least one of the inner and outer cylindrical walls that are in contact with each other. An annular groove is provided in the outer floating shaft, an inner floating shaft, and a shaft of the shaft cylinder, and an appropriate number of through holes are provided at positions corresponding to the annular grooves on each axis of the outer floating shaft, inner floating shaft, and shaft cylinder. A fluid passage is formed from the shaft to the shaft cylinder. and,
The bearing base has a communication hole that is a fluid intake port that communicates with the annular groove of the cylindrical wall where the bearing base and the outer floating shaft are in contact with each other, and fluid is supplied from the inside of the cylinder of the shaft cylinder to the outside. .

(Operation) The fluid coupling of the present invention has four degrees of freedom: three-dimensional translational movement in XYZ and rotational movement around the shaft cylinder. That is, it is composed of a bearing base A, an outer floating shaft B, an inner floating shaft C, and a shaft cylinder D.
As shown in FIG. 9, it has a concentric cylindrical structure whose central axis is the central axis P of the joint body 21. As shown in FIG. 9, the outer floating axis B has an outer cylindrical surface centered on the central axis P of the joint body 21, and an inner cylindrical surface centered on Q, which is separated by _l3 from this axis P. have,
It is inserted along the cylindrical inner wall of the bearing base A.

The inner floating shaft C has an outer cylindrical surface whose _central axis is the axis Q shown in FIG. inserted along.

The shaft cylinder D has a concentric cylindrical structure with the axis O as the central axis, and is inserted along the inner wall of the cylinder of the inner floating shaft C.

By superimposing such rotational movements of the eccentric cylinder, translational movement with two degrees of freedom in a plane perpendicular to the cylinder axis can be realized as follows. In other words, in Fig. 9, for example, a force is applied to the central axis O of the shaft cylinder D in the X direction.
When F ₁ acts, a clockwise rotational moment F ₁ l ₂ cosθ ₂ about the axis Q acts on the inner floating axis C, and the inner floating axis C rotates clockwise as shown by the black arrow. At the same time, a clockwise rotational moment F ₁ l ₁ cosθ ₁ about the axis P acts on the outer floating shaft B, and the outer floating shaft B rotates clockwise about the axis P as the black arrow. By combining the rotational motions of the two floating shafts, the central axis O of the shaft cylinder moves in the X-axis direction with the motion in the Y-axis direction cancelled.

In another case, a force is applied to the cylinder center axis O in the Y direction.
When F ₂ acts, the inner floating axis C receives a clockwise rotation moment F ₂ l ₂ sin θ ₂ about the axis Q, and the inner floating axis C rotates clockwise about the axis Q as shown by the white arrow. Rotate. At the same time, the outer floating axis B has a counterclockwise rotational moment about the axis P.
F ₂ l ₁ sin θ ₁ acts, and the outer floating shaft B rotates counterclockwise about the axis P as the white arrow. By combining the rotational motions of these two floating shafts, the central axis O of the shaft cylinder is moved in the Y-axis direction, with the motion in the X-axis direction cancelled.

By combining the rotational motion of the inner and outer floating axes,
The range in which the central axis O of the shaft cylinder D can move within a plane perpendicular to it, that is, within the plane of the paper in Fig. 9, is within a circle with radius R = l ₃ + l ₂ centered on point P (within the double-dashed line circle in the figure). )
This allows for a much wider range of motion than conventional joints. In addition, translational movement in the axial direction of the shaft cylinder D, rotational movement around the axis of the shaft cylinder D,
It can have a total of four degrees of freedom.

These bearing base A, outer floating shaft B, inner floating shaft C
An annular groove is provided on at least one of the corresponding inner and outer surfaces of the shaft cylinder D, and
The inner and outer cylindrical walls of the outer floating shaft B, the inner floating shaft C, and the shaft cylinder D are connected to each other by an appropriate number of through holes in the portions corresponding to the annular grooves, so that the inner and outer cylindrical walls of the outer floating shaft B, the inner floating shaft C, and the shaft cylinder D are connected to each other by an appropriate number of through holes. The high-pressure air introduced into the shaft flows into the inside of the shaft cylinder D through the annular groove and the through hole due to the relative rotational movement of each shaft and axial displacement within a permissible range. I can do it.

(Example) Examples will be described in detail.

In the embodiment shown in FIG. 5 and below, the eccentric journal air joint body 21 is composed of the bearing base A, the outer floating shaft B, the inner floating shaft C, and the shaft cylinder D as described above. As shown in FIG. 9, the bearing base A has a concentric cylindrical structure having the central axis P of the joint body 21 as its central axis. The lower surface of the cylinder has one or several high-pressure air intake ports 22, but the air supply pipe and the shaft cylinder D
If it is necessary to arrange the cylinder at a right angle, an inlet opening to the cylindrical outer wall surface 28 may be provided. An annular inner groove 23a is provided in the center of the inner wall of the cylinder, and communicates with the high pressure air intake port 22 through a communication hole 24 to form a high pressure air path. The upper and lower cylindrical inner wall portions of the annular inner groove 23a are precisely machined to form air bearing lubricating surfaces 25a, 25a'. This lubricating surface 2
There are annular small grooves 26a, 26 in the center of 5a, 25a'.
a' is provided and communicated with the cylindrical outer wall surface 28 through a large number of air discharge holes 27a, 27a' to discharge lubricating air. In addition, a large number of ejection holes 29a are vertically provided from the annular inner groove 23a to the upper surface of the bearing base A, and an air cushion lubricating surface 31a is formed between the lower surface of the buoyancy flange 30b provided on the upper part of the outer floating shaft B, and the outer Floating axis B
It has the effect of floating the bearing base A relative to the bearing base A.

As explained in FIG. 9, the outer floating axis B has an outer cylindrical surface centered on the central axis P of the joint body 1, and an inner cylindrical surface centered on the center axis Q, which is separated by _l3 from this axis P. , and the above-mentioned buoyancy flange 30b is attached to the upper end.
It is inserted along the inner wall of the cylinder of the bearing base A. An annular outer groove 32b is provided on the cylindrical outer wall surface of the outer floating shaft B at a position corresponding to the annular inner groove 23a of the bearing base A, and an annular inner groove 23b is provided at a corresponding position on the cylindrical inner wall surface. They are connected by a through hole 33 to form a high pressure air passage. The upper and lower cylindrical outer wall surfaces of the annular outer groove 32b and the upper and lower cylindrical inner wall surfaces of the annular inner groove 23b are precision-machined to form air bearing lubricating surfaces between the bearing base A and the inner floating shaft C, respectively. The lubricating air supply jet holes 34b and 34b' from the annular outer groove 32b are connected to the lubricating surface 25.
b, 25b', and supplies lubricating air to the gap between the lubricating surfaces 25a and 25b and the gap between 25a' and 25b'. Furthermore, in order to increase the lubrication efficiency, an appropriate number of holes 35b are provided in the buoyancy flange 30b for releasing air that has passed through the air cushion lubricating surface 31a formed above the gap between the bearing base A and the outer floating shaft B. .

Small annular grooves 26b, 26b' are provided in the center of the upper and lower lubricating surfaces of the annular inner groove 23b, and a large number of air release holes 27b, 27b' communicating with the outside world are provided here. It is similar to the discharge hole 27a, but the discharge holes 27b, 2
7b' opens on the upper and lower surfaces of the outer floating shaft B, respectively.
In addition, a large number of ejection holes 29b are provided which communicate from the annular inner groove 23b to the upper surface of the outer floating shaft B.
An air cushion lubricating surface is formed between the lower surface of the upper buoyant flange 30C and the inner floating shaft C floats relative to the outer floating shaft B. Thickening hole 36
b is provided to balance the weight distribution of the outer floating axis B so that the center of gravity is on the axis P.

As seen in Fig. 9, the inner floating axis C is the outer cylindrical surface centered on the axis Q, and the axis O is located _l2 apart from the axis Q.
It is an eccentric cylinder having an inner cylindrical surface with the center axis at , and a buoyancy flange 30c provided on the upper part, and is inserted along the inner wall of the cylinder of the outer floating shaft. The structure consists of annular grooves on the inner and outer walls, which are communicated through radial holes to form high-pressure air passages, and air bearing lubricating surfaces on the upper and lower sides of the annular grooves. It is the same as axis B. However, since the shaft cylinder D does not have a buoyancy flange, it lacks a structure corresponding to the air jet hole 29b. Further, the lightening hole 36C is provided so that the center of gravity is on the axis Q.

The shaft cylinder D has a flange 3 for connecting the model side piping on the upper surface.
0d, a stopper plate 38 is provided on the lower surface, forming a concentric cylindrical structure with the axis O as the central axis, and is inserted along the inner wall of the cylinder of the inner floating shaft C. An annular outer groove 32d is provided at a position corresponding to the annular inner groove 23c of the inner floating shaft C on the outer wall surface of the shaft cylinder, and is connected to the inside 41 of the shaft cylinder D by a through hole 39 to form a high-pressure air passage. . The upper and lower cylindrical outer walls of the annular outer groove 32d have inner and outer floating axes B and C.
Similarly, the air bearing lubricating surface is formed by precision machining, and lubricating air is supplied to the gap between the inner floating shaft C and the inner floating shaft C from the shaft cylinder interior 41 through the jet hole 34d.
A stopper plate 38 is installed to prevent the outer floating shaft B, inner floating shaft C, and shaft cylinder D from moving upward by more than the limit amount.
is attached to the lower surface of the shaft cylinder D, and is adapted to hit and be locked against the bottom surface 42 of the bearing base.

Next, the function of this air joint will be explained.

Eccentric journal air joint body 21 of this embodiment
As shown in Figs. 5 and 6, the pipe is installed on the wind tunnel wall so that the center axis Z is vertical, and a pipe from a high-pressure air source separately provided is connected to the high-pressure air intake port 22 on the lower surface of the bearing base A. 40 is fixed. Next, the outer floating shaft B, the inner floating shaft C, and finally the shaft cylinder D are inserted while maintaining a gap of several tens of microns between the cylinder walls between each shaft. High pressure air flows from the pipe 40 through the high pressure air intake port 22 and the communication hole 24 into the annular inner groove 23a. The high pressure air that has flowed in here is passed through the through holes 33 and 33 between each shaft.
Inner and outer annular grooves 23a, b, communicating at 37, 39,
c, 32b, c, and d, no matter what positional relationship the respective axes have, a stable high-pressure air flow always flows into the interior 41 of the shaft cylinder D, and the model inside the wind tunnel is supplied to. On this occasion,
A small amount of air in the high-pressure air passage is used as lubricating air for the air bearing lubricated surfaces and as air cushion air to levitate the outer floating shaft B and the inner floating shaft C, as will be explained in detail next. be done.

The structure and operation of the air bearing and the air cushion are as shown in FIG. 8, which is a partially enlarged view of FIG. A small amount of lubrication is supplied to the gap between the cylindrical walls directly from the high-pressure air chamber formed by the annular inner groove 23a and the annular outer groove 32b, and from the jet nozzle 34b provided on the outer floating shaft B. High-pressure air is supplied for use, and a portion of this air is passed from the annular small groove 26a of the bearing base A to the discharge port 27.
a, and the other part is released into the atmosphere from the discharge hole 35b provided in the buoyancy flange 30b of the outer floating shaft B, and this flow creates a uniform high pressure in the cylindrical gap of several tens of microns. An air layer is formed. Such a high-pressure air layer exists between the bearing base A and the outer floating shaft B, as well as between the outer floating shaft B and the inner floating shaft C, and the inner floating shaft C.
It is formed between the air bearing lubricated surfaces between the shaft cylinder D and the shaft cylinder D, and mutual rotation and translation of these shafts is performed with extremely low resistance.

On the other hand, high-pressure air is supplied to the gap between the upper surface of the bearing base A and the lower surface of the buoyancy flange 30b at the upper end of the outer floating shaft B from the jet hole 29a vertically installed from the annular inner groove 23a, and some of the air is supplied to the outer floating shaft. A part of the air is released into the atmosphere from the outer edge of the flange of the shaft B through a discharge hole 35b provided in the flange 30b of the outer floating shaft B, and a uniform high-pressure air layer is formed on the lubricated surface of this gap.
The weight of the outer floating shaft B is supported by this air cushion pressure. Such an air cushion function is also achieved by the lubricating surfaces of the upper surface of the outer floating shaft B and the lower surface of the flange at the upper end of the inner floating shaft C. As a result, the outer floating shaft B and the inner floating shaft C are supported by the bearing base A without friction and can maintain their mutual positions.

In this embodiment, the air joint main body 21 is held vertically, so the upper part can be supported by the air cushion, but if it is to be used horizontally or upside down, The structure may have floating shaft flanges on both sides.

In this embodiment, the bearing base A and the outer floating shaft B, the outer floating shaft B and the inner floating shaft C, and the inner floating shaft C
An annular groove is provided on both the inner and outer walls of the adjoining cylindrical cylinders D, and if an annular groove is provided on at least one of the adjoining inner and outer walls of the cylinder, a fluid passage for high-pressure air is formed. I can do it. moreover,
In addition to supplying high pressure fluid from the bearing base side,
It goes without saying that, on the contrary, it may be supplied from the shaft cylinder side to the bearing base side.

(Application example) As an example of the use of the eccentric journal air joint according to the embodiment of the invention described above, in a wind tunnel test of an aircraft model equipped with a simulated engine using high-pressure air, the aerodynamic force acting on the model is accurately measured using a balance. Figure 10 shows a case in which this air joint is installed in the middle of a high-pressure air piping for this purpose.

In a wind tunnel test of a semi-mounted aircraft model 44 equipped with a simulated engine 43, the eccentric journal air joint body 21 of this embodiment was fixed to a base 46 provided in contact with the outside of the wind tunnel wall 45, and the high pressure A high-pressure pipe 40 is connected to the air intake port to supply high-pressure air and send wind W. The balance body 47 for measuring the aerodynamic force acting on the model is arranged around the shaft cylinder D between the wind tunnel wall 45 and the air joint body 21, and has an inner fixing ring 49 to which one end of the balance sensing element is fixed. It is fixed to the shaft cylinder D, and the other outer fixed end 48 is attached to the base 4.
It will be posted on 6. The shaft cylinder D passes through a hole 50 in the wind tunnel wall 45, has a flange surface 51 connected to an air supply port 52 fixed to the body of the model 44, and moves integrally with the model 44.

In a semi-mounted model wind tunnel test of an aircraft with the main wing vertically installed, the force components that are required to be measured are lift force Y, resistance (thrust force) X, and pitching moment M. Of these, the lift and drag (thrust) components are:
As previously explained about the operation of the joint of the present invention, due to the combination of the low-friction rotational motion around the cylindrical axis of the outer floating shaft B and the inner floating shaft C of the air joint body 21 of the embodiment, the pitching moment is The low-friction rotational motion of the tube D around the cylindrical axis acts on the balance sensing element, making the pipe interference force extremely small and allowing highly accurate measurement. Moreover, since the movable range within the plane of the shaft cylinder D is wide, the work of assembling the balance 47, the air joint body 21, the model 44, and the high-pressure piping becomes easy.

The embodiments in which the present invention is used as a journal air joint have been described above, but the invention is not limited to air joints, but can also be used for other types of gases, liquids, etc. When the force applied to the shaft cylinder D is large, instead of using a fluid bearing as in this embodiment,
Other types of bearings can also be used, for example ball bearings.

Effects of the Invention As described above, this invention realizes a fluid coupling with four degrees of freedom by combining a cylindrical shape that is easy to work with high precision by using an eccentric shaft, and moreover, by introducing an air bearing. As a result, we were able to reduce piping interference force by about two orders of magnitude compared to conventional systems. Furthermore, since the fluid supply pipe 40 and the shaft cylinder D relative to the fluid coupling body 21 are capable of three-dimensional translational movement, by incorporating them in the middle of the fluid transfer piping, there is also the effect that misalignment of the piping can be absorbed. be.

[Brief explanation of the drawing]

1 to 4 are explanatory diagrams of a known air coupling, FIG. 5 is a partially cutaway perspective view of an embodiment of the eccentric fluid coupling of the present invention, FIG. 6 is a vertical sectional view, and FIG. The figure is also a horizontal sectional view, and Figure 8 is the 6th section.
An enlarged view of the circular outline in the upper right part of the figure, FIG. 9 is an explanatory diagram of the operation of the eccentric journal air joint of this embodiment, and
Figure 0 is a perspective view of an example of use in a wind tunnel test. The symbols in the figure indicate the following, respectively. 1: Aircraft model, 2: Flexible pipe, 3: Balance,
4: Air supply pipe, 5: Joint part, 6: Annular groove,
9: Outlet pipe, 10: Ball shell, 21: Eccentric journal air joint body, 22: Air intake port, 2
3: Annular inner groove, 24: Communication hole, 25: Air bearing, 26: Small groove, 27: Air release hole, 28: Outer wall surface, 29: Ejection hole, 30: Buoyancy flange, 3
1: Air cushion lubricating surface, 32: Annular outer groove, 3
3, 37, 39: Through hole, 34: Air blowout hole, 3
5: Air release hole, 36: Lightening hole, 38: Stopper, 40: High pressure air piping, 41: Shaft cylinder, 42:
Bearing base bottom, 43: Simulated engine, 44: Half-mounted model, 45: Wind tunnel wall, 46: Base, 47: Balance body, 48: Outside fixed end, 49: Inside fixed end, 5
0: hole, 51: flange, 52: air supply port.

Claims (1)

[Scope of Claims] 1 Consists of a bearing base, an outer floating shaft, an inner floating shaft, and a shaft cylinder, each of the outer floating shaft and the inner floating shaft having a cylindrical inner wall eccentric with respect to the cylindrical outer wall, and the shaft cylinder The inner floating shaft is rotatably inserted and held within the cylindrical inner wall of the inner floating shaft, the outer floating shaft is inserted and held within the cylindrical inner wall of the outer floating shaft, and the outer floating shaft is rotatably inserted and held within the cylindrical inner wall of the bearing base. An annular groove is provided in at least one of the adjoining inner and outer walls of each of the outer floating shaft, the outer floating shaft and the inner floating shaft, and the inner floating shaft and the shaft cylinder, and each shaft of the outer floating shaft, the inner floating shaft, and the shaft cylinder is provided with an annular groove. Its inner and outer walls are communicated through a suitable number of holes at positions corresponding to the annular groove to form a fluid passage from the bearing base to the shaft cylinder, and the bearing base is connected to the bearing base and the outer floating shaft. An eccentric fluid coupling characterized in that it has a communication hole that communicates with annular grooves of adjacent cylindrical walls, and the communication hole and the inside of the cylinder of the shaft cylinder are connected to a fluid supply source and a supplied body, respectively. 2 The inner and outer cylindrical walls of the bearing base, outer floating shaft, inner floating shaft, and shaft cylinder face each other with a small gap in the area other than the annular groove, and high-pressure fluid is introduced into this gap to create a fluid bearing. The eccentric fluid coupling according to claim 1, characterized in that the eccentric fluid coupling is formed with: 3. The eccentric fluid coupling according to claim 2, wherein the high-pressure fluid flows within the annular groove. 4. Buoyancy flanges are provided at the upper ends of the outer floating shaft, inner floating shaft, and shaft cylinder, and high-pressure fluid is introduced into the gaps between these flanges and the upper surfaces of the bearing base, outer floating shaft, and inner floating shaft, and this fluid layer is Therefore, the outer floating shaft,
The eccentric fluid coupling according to claim 2, characterized in that it supports an inner floating shaft and a shaft cylinder.