JPH01242817A - Hydrodynamic foil bearing - Google Patents

Abstract

PURPOSE:To make a bearing optimum as one for a high speed rotating body by spirally inserting a metallic sheet having metallic wires fixed on its one surface between a housing and a rotating shaft, and fixing the outside end of the metallic sheet to the housing. CONSTITUTION:A metallic sheet 3 having plural metallic wires 2 fixed on its face is spirally inserted into an annular gap 5 between the inner periphery of the housing 1 and a rotating shaft 4 inserted into the housing 1 to fix the outside end of the sheet 3 to the housing 1. Thus the most inside face of the sheet 3 comes into contact with the outer peripheral face of the shaft 4 to function as a bearing face, and a fluid film is formed between the bearing face and the surface of the shaft 4 during its rotation to perform bearing action. The sheet 3 therefore functions as the optimum bearing for a high speed rotating body.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] This invention relates to a hydrodynamic foil bearing for high-speed rotating bodies.

[Prior Art] In addition to general machines, a turbocharger for an automobile can be exemplified as a high-speed rotating body.

In recent years, for example, the adoption of turbochargers in automobiles has rapidly increased, starting with installation in large trucks and now spreading to small passenger cars and motorcycles.

In order to improve performance, they have become smaller, lighter, and faster.

Conventionally, oil-lubricated floating bushier bearings have been used as turbocharger bearings, but several problems arise on the turbine side, which is exposed to high-temperature exhaust gas from the engine room.

That is, the viscosity decreases due to the rise in oil temperature, the lubricating performance decreases due to deterioration, the oil leakage from the seal increases, and there is a risk of fire.

For this reason, the conditions required for bearings for turbochargers are particularly important, such as high-speed stability, impact resistance, and foreign object resistance.At the same time, it is desired that the bearings be compact and low-cost. Hydrodynamic foil bearings are promising as a bearing type that satisfies these requirements.

The basic idea behind hydrodynamic foil bearings is that the bearing surface is made of metal foil (hereinafter referred to as a thin metal sheet), and the bearing surface is superior due to its IQ properties and the damping effect of the thin fluid film formed between the thin metal sheet and the rotating shaft. In addition, the flexibility of the thin metal plate is intended to provide excellent characteristics against contamination by foreign matter and misalignment.

As a conventional hydrodynamic foil bearing, for example,
The one shown in No. 29649 is known.

The hydrodynamic foil bearing described above has multiple metal thin plates installed at regular intervals in the circumferential direction on the inner peripheral surface of the housing into which the rotating shaft is inserted. The structure is such that the rotating shaft is hydrodynamically supported by a thin fluid film formed on the outer peripheral surface of the rotating shaft and the bearing surface.

[Problem to be solved by the invention]

By the way, the hydrodynamic foil bearing with the structure described above has the problem that because the thin metal plates are arranged intermittently, the area where a fluid film is generated is small, making it difficult to obtain a sufficient effect as a bearing for high-speed rotation. There is.

In addition, it is necessary to adjust the bonding force of each thin metal plate to the rotating shaft from the outside of the housing in response to changes in the rotating speed of the rotating shaft, which makes the structure complex and increases the overall size. There is a problem.

This invention was made to solve the above-mentioned problems, and the purpose is to provide a hydrodynamic foil bearing that is small in size, can handle high-speed rotation, and is optimal as a bearing for high-speed rotating bodies. There is.

[Means to solve the problem]

In order to solve the above-mentioned problems, the present invention provides a thin metal plate having a plurality of metal wires fixed at appropriate intervals in the longitudinal direction on one side, in the gap between the housing and the rotating shaft inserted into the housing. The thin metal plate is inserted in a spiral shape so that the other side faces the outer peripheral surface of the rotating shaft, and the outer end of the thin metal plate is fixed to the housing.

[Effect]

With one end of the thin metal plate spirally inserted into the gap between the housing and the rotating shaft fixed to the housing, the innermost surface of the thin metal plate in contact with the outer peripheral surface of the rotating shaft becomes the bearing surface, and when the rotating shaft rotates, the shaft surface A bearing action is performed by forming a fluid film between the two.

〔Example〕

Embodiments of the present invention will be described below with reference to the accompanying drawings.

As shown in Figure 1, a hydrodynamic foil bearing is roughly divided into two parts, one of which is a housing 1 that defines the overall shape of the bearing, and the other is a housing 1 that defines the shape of the entire bearing. This is a thin metal plate 3 to which a metal wire 2 is attached.

As shown in FIGS. 2 and 3, the metal thin plate 3 is formed into a band shape using a phosphor bronze plate or the like, and a metal wire 2 made of piano wire is attached to the entire length of one side in the width direction of the metal thin plate 3. 3 are fixed at appropriate intervals in the longitudinal direction.

As shown in FIG.
The thin metal plate 3 is inserted in a spiral shape so that the other side faces the outer circumferential surface of the rotating shaft 4, and the outer end of the thin metal plate 3 is inside the housing.

The thin metal plate 3 is fixed to the housing 1 by wrapping and fixing a pin 6 around one end of the thin metal plate 3 and inserting a pin 6 into a mounting hole 7 provided on the inner surface of the housing 1. The thin metal plate 3 is inserted into the annular gap 5 in a spiral manner so as to be wound in the rotational direction of the rotating shaft 4 from the inner end thereof.

The bearing of the present invention has the above-described structure, and includes a thin metal plate 3 inserted between the inner periphery of the housing 1 and the annular gap 5 between the rotating shaft 4.
The innermost circumferential surface of the bearing surface 8 becomes the bearing surface 8, and this bearing surface 8 and the rotating shaft 4
By forming a fluid film (gas film, liquid film) between the bearing and the outer circumferential surface of the bearing, it acts as a bearing for the rotating shaft 4, and is used as a bearing for various machines that rotate at high speed and for turbochargers.

As mentioned above, since the metal wires 2 are fixed to one side of the thin metal plate 3 at predetermined intervals, the thin metal plate 3 inserted spirally into the annular gap 5 with the metal wires 2 serving as spacers is made of metal. The area between the wires 2 can be elastically deformed, and the excitation energy is absorbed by this elastic deformation, the squeezing effect of the fluid film between the thin metal plates 3 or between the thin plates 3 and the housing 1, and the Coulomb Ft friction between the thin plates 3 and the metal wires 2. Absorbs and damps to improve stability at high speeds.

Furthermore, due to the flexibility of the thin metal plate 3, it is possible to deal with the intrusion of foreign matter.

Next, the method and results of an experiment conducted on the rotational performance of the hydrodynamic foil bearing will be explained below.

Four types of housings 1 were manufactured with inner diameters ranging from 18.03 to 18.15 mm in order to vary the bearing clearance.

The thin metal plate 3 has a thickness of 0.05an++ and a width of 19.5rl.
Using the phosphor bronze plate of a, prepare three types of metal wires 2 using piano wire with a diameter of 0.2 m on one side, 9, 18, and 27 adhesively fixed, and each metal thin plate 3, A test bearing was formed by attaching to the housing 1 by inserting a pin 6 with a diameter of 5III with a fixed winding at one end into the attachment hole 7 of the housing 1.

FIG. 4 is a schematic diagram of the rotational performance test device. In the same figure, the rotating shaft 11 is made of stainless steel and has a part of its surface treated with ion nitriding. It has a diameter of 17 m, a length of 220 m+, and a mass of 0.
．． The turbine blade 12 for rotational drive is attached to the center, and the positions near both ends are supported by the above-mentioned test bearings (hydrodynamic foil bearings 10.10), and both ends are It is supported in the thrust direction by a thrust bearing 13 that blows compressed air.

The rotating shaft 11 is rotated by an air turbine drive, and the vibration amplitude of the rotating shaft 11 is measured in the horizontal and vertical directions near the shaft end using a non-contact displacement meter 14.

In addition, the reaction torque acting on the rotating shaft 11 is detected by supporting one hydrodynamic foil bearing 10 with a hydrostatic air journal bearing 15, and detecting the torque acting on the hydrodynamic foil bearing 10 with a torque sensor 16 using a strain gauge. .

Experimental results: (1) Turbine supply pressure and shaft rotation speed - Figures 5 and 6 show the results of measuring the relationship between turbine supply pressure and shaft rotation speed by changing the bearing radial clearance C and the number of metal wires n. . Experimental results for a hydrostatic air bearing are also shown for comparison. The hydrostatic air bearing used here has a width of 190 mm and a bearing radius clearance of 15 mm.
n, a single row of 8 air supply holes equally spaced (hole diameter 0.5m+++, self-diaphragm), and a rotation test was conducted at a supply pressure of 0.49 MPa. In the hydrodynamic foil bearing 10, since the starting torque is large, a smooth increase in rotation in a low speed range cannot be obtained as in the case of a hydrostatic bearing, but a smooth increase in speed can be obtained in a high speed range. In terms of the number of metal wires, the one with nine metal wires is a little inferior.

(2) Shaft vibration - The relationship between the vibration amplitude of the rotating shaft and the rotation speed is
As shown in Fig. and Fig. 8. FIG. 7 shows the measurement results of the vibration amplitude in the vertical direction (load direction) when n=18, and FIG. 8 shows the measurement results of the vibration amplitude in the horizontal direction when n=27.

From this, it can be seen that a relatively large bearing gap exhibits stable characteristics. Also, in both cases, 96.00O
The vibration amplitude rapidly increased around rpm (the natural frequency of the shaft), and it was not possible to increase the speed any further, but it was found from the analysis of the vibration waveform that so-called half-frequency whirl did not occur. For comparison, the experimental results using the above-mentioned hydrostatic bearing are shown in FIG. As the boost pressure increases, the maximum rotational speed increases, but in both cases, half-frequency whirl occurred.

(3) Shaft torque - acting on the rotating shaft (in order to know the friction torque, the reaction torque acting on the bearing was measured. Examples of measurement results are shown in Figures 10 and 11. When the number of metal wires is small (n
=9), stable torque characteristics were not obtained, but stable characteristics were obtained when the number of metal wires was large.

In particular, the one with 27 metal wires shows a rapid transition of the fluid lubrication film after startup. In this case, the larger the bearing clearance, the smaller the starting torque.

(4) Durability - In order to investigate the durability of the prototype hydrodynamic foil bearing, we observed surface damage to the rotating shaft and bearing surface (metal thin plate surface) due to repeated starting and stopping movements, and rotational characteristics due to repeated operation. The change in was measured experimentally. Here, a repeated operation test was conducted 50 times, and the rotational characteristics were examined every fifth time.Other times, the speed was increased from startup to ascent (0 to 50, OOOrpm), and then the speed was immediately lowered to a stop. FIG. 12 shows how the friction torque acting on the rotating shaft changes with repeated operation. The starting torque increases with the number of repetitions. This is thought to be because the MO52 powder applied to the rotating shaft surface and the thin metal plate surface before assembly was scattered. However, other than that, there is not much change in torque due to repeated operation, and overall it can be seen that it is more stable after repeated operation.

FIG. 13 shows changes in the vibration characteristics of the rotating shaft 11. Overall, no deterioration in characteristics was observed due to repeated operation; rather, during the first rotation test, 50,000
Vibration characteristics are poor at high speeds above rpH.

It is stable and even appears to be stable after repeated operation. The cause of this is that during the first rotation test, the MoS z powder applied to the lubricated surface was scattered and moved within the bearing gap, causing an adverse effect, and that the shape of the thin metal plate adapted to the rotating shaft due to repeated operations. Conceivable.

FIG. 14 shows the relationship between turbine supply pressure and shaft rotation speed. The relationship between the two did not change at all after 50 repeated rotation tests. In addition, there was only slight damage to the surface.

〔effect〕

As described above, according to the present invention, a thin metal plate with a metal wire fixed to one side is spirally inserted into the annular gap between the housing and the rotating shaft, and the outer end of the thin metal plate is fixed to the housing. The other side of the thin metal plate facing the outer circumferential surface of the rotating shaft becomes the bearing surface, and a fluid film is formed between it and the outer circumferential surface of the shaft to perform a bearing action and achieve stable high-speed rotation of the rotating shaft. It has a wide range of uses as a bearing for high-speed rotating bodies.

In addition, the thin metal plate is spirally inserted into the annular gap between the rotating shaft and the housing, and the outer end of the thin metal plate is fixed to the /＼wing, so the structure is simple and the whole can be made compact. It can meet the requirements for bearings for various high-speed rotating machines and turbochargers.

[Brief explanation of the drawing]

Fig. 1 is a longitudinal sectional front view of a hydrodynamic foil bearing according to the present invention, Fig. 2 is a perspective view of a thin metal plate used in the same, Fig. 3 is a front view of the same, and Fig. 4 is a rotational performance test device. Each of the explanatory diagrams, FIGS. 5 to 14, is a graph showing the results of various performance tests of hydrodynamic foil bearings. DESCRIPTION OF SYMBOLS 1... Housing, 2... Metal wire, 3... Metal thin plate, 4... Rotating shaft, 5... Annular gap, 6・・・・・・
Pin, 7...Mounting hole, 8...
Bearing surface, 10...Hydrodynamic foil bearing. Patent applicant Osaka Sangyo University Academic Corporation Agent Kama 1) Text - Figure 6 Figure 7 Figure 8 $9 Figure 10 Figure 11 Figure 12 o 2 4 bb Heart rotation 1B, (rpm) 13 Figure 14 Turbine salary (C Monthly X (MPa)

Claims (1)

[Claims] (1) A thin metal plate with multiple metal wires fixed at appropriate intervals in the longitudinal direction on one side is placed in the gap between the housing and the rotating shaft inserted into the housing, with the other side of the thin metal plate facing the outer peripheral surface of the rotating shaft. a hydrodynamic foil bearing, the outer end of said metal sheet being fixed to the housing in a spiral manner so as to be directed toward the housing;