JPS626335Y2 - - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to a thrust gas bearing structure, and in particular, the rigidity of an annular bearing member that is provided on the bearing case support surface surrounding the rotating shaft to support the thrust load of the thrust collar. The present invention relates to a thrust gas bearing structure that can be formed distributed over the entire circumferential direction in accordance with the gas film pressure, has excellent stability and load capacity, and has a simple configuration and is easy to assemble.

Gas bearings are a type of bearing that supports the shaft by forming a gas film between the shaft and the bearing surface, so it has low friction loss and is suitable for turbo compressors, turbo expanders, turbo chargers, turbo refrigerators, etc. Extremely suitable for high-speed rotating shafts. Rigid bearings and foil bearings are known as this type of bearing, but in rigid bearings, the gas film breaks due to shaft deformation, etc.
Currently, foil bearings are being researched and developed. However, conventional oil bearings do not have a sufficient mechanism to attenuate fluctuations in gas film pressure caused by vibrations of the rotating shaft, and have the disadvantage of becoming unstable during high-speed rotation.

Therefore, the inventor of the present invention devised a new foil bearing (Japanese Patent Application No. 70885/1985) which eliminates this drawback. The thrust bearing structure according to this invention is shown in FIG.
This will be explained based on FIG. In the figure, a is a metal thin plate annular spring foil, b is a circular comb-shaped foil, and comb-shaped foil b
has comb teeth c along the radial direction at equal pitches in the circumferential direction. As shown in FIG. 1, the spring foil a is inserted so that the comb teeth c of the comb-shaped foil b alternately appear on the front and back sides of the spring foil a. Therefore, in this way, the spring foil a
The assembly with the comb-shaped foil b functions as an elastic body with spring elements distributed between the comb teeth c and c. The thrust bearing of this invention is
This resilient body supports a bearing surface member whose surface serves as a bearing surface.

However, in order to insert the annular spring foil a into the comb-shaped foil b, it is necessary to cut the spring foil a at one point in its radial direction, as shown in FIG. For this reason, the rigidity of the projectile differs at the cut part, and the rigidity becomes uneven.
As will be described later, this cut location obstructs the transmission of the circumferential "undulations" of the elastic body, which effectively act on the generation of gas film pressure. Furthermore, the work of assembling the small-diameter spring foil a and the comb-shaped foil b is difficult and time-consuming.

The present invention was devised to effectively solve the above-mentioned conventional drawbacks, and the purpose of the present invention is to adapt the rigidity of the bearing member to the gas film pressure and to form a distribution in the circumferential direction of the bearing member. It is an object of the present invention to provide a thrust gas bearing structure that can dramatically improve bearing performance, has a simple configuration, and is easy to assemble.

Examples of the present invention will be described below.

FIG. 3 shows a circumferential cross section of a bearing portion of a rotating shaft of a turbo compressor or the like. In the figure, 1 is a thrust collar of a rotating shaft, and the thrust collar 1 is rotating in the U direction. Further, in order to support the thrust load W of the thrust collar 1 by forming a gas film, a bearing case 2 is provided facing the thrust collar 1 and facing it, and the bearing surface 3 of the bearing case 2 is provided with a rotating shaft. An annular bearing member 4 surrounding the bearing member 4 is attached. The bearing member 4 is made by laminating elastic thin plates (hereinafter referred to as foils), and a top foil 5, a comb-shaped foil 7, a spring foil 6, and a comb-shaped foil 8 are sequentially stacked from the thrust collar 1 side toward the bearing case 2. It is constructed by overlapping. These foils 5, 6, 7, and 8 are all annular, and their plan views are shown in FIGS. 5 to 8, respectively.

The Topf oil 5 is a bearing surface member whose surface becomes a bearing surface, and on the surface of the Topf oil 5, as shown in FIG. 5, a spiral groove 9 for generating gas film pressure is formed.
The spring foil 6 also has a plurality of mounting holes 6a (six in the illustrated example) at appropriate intervals on its outer periphery for fixing it in a stacked state with other foil elements such as the comb foil 7. Similarly, the spring foil 6 also has mounting holes 6a on its outer periphery (see FIG. 6).

As shown in FIG. 7, the comb-shaped oil 7 includes a ring-shaped outer circumference 7b and comb teeth 7 extending radially from the inner circumference toward the center of the comb-shaped oil 7.
A plurality of comb teeth 7c are provided radially at equal pitches along the outer peripheral portion 7b. Further, the outer peripheral portion 7b of the comb-shaped oil 7 is provided with a mounting hole 7a. In addition, comb-shaped oil 8
also has the same shape and dimensions as the comb-shaped oil 7,
Comb teeth 8c are provided at equal pitches on the outer peripheral portion 8b, and attachment holes 8a are provided. The structural difference between the comb-shaped oil 7 and the comb-shaped oil 8 is that the mounting holes 7a, 8 for the comb teeth 7c, 8c are
There is a shift in the machining position of a. That is, the mounting holes 7a,
8a is the comb teeth 7c, 8c provided at equal pitches.
They are placed 1/2 pitch apart from each other. Therefore, when the top oil 5, the comb oil 7, the spring oil 6, and the comb oil 8 are installed in the bearing case 2 with their mounting holes 5a, 7a, 6a, and 8a aligned, as shown in FIG. The comb teeth 7c and 8c are alternately arranged at 1/2 pitch on both sides of the spring foil 6 along the circumferential direction.

Next, the operation of this embodiment will be described.

The bending rigidity of the foil material constituting the foil gas thrust bearing is significantly lower than the rigidity of the gas film generated between the bearing surfaces. Therefore, it is difficult to form a stable gas film with a single foil, and it is necessary to devise a combination of foils to obtain an appropriate foil rigidity corresponding to the rigidity of the gas membrane. Generally, it is desirable that the stiffness of the foil bearing be designed to be on the same order of magnitude as or less than the stiffness of the gas membrane.

However, in the thrust gas bearing of the present invention, the top oil 5 is supported by sandwiching the spring oil 6 with comb-shaped oils 7 and 8 whose comb tooth rows are shifted by 1/2 pitch from each other. The elasticity can be distributed uniformly in the circumferential direction. In addition, the rigidity of the bearing member 4 is
A desired value can be selected by changing the thickness of the spring oil 6 and top oil 5 or the pitch of the comb teeth 7c, 8c. Therefore, the thrust gas bearing of the present invention can be easily adapted to the optimal rigidity conditions for the thrust bearing described above. Note that it is also easy to reduce the rigidity of the bearing member by alternately stacking spring foils and comb-shaped foils in multiple layers, such as double or triple, between the comb-shaped foil 8 and the bearing surface 3 of the bearing case 2. .

Furthermore, when the thrust collar 1 rotates, a gas film is generated between the thrust collar 1 and the topf oil 5 in order to support the thrust load W, but the pressure of this gas film acts on the topfoil 5 surface, causing the topfoil 5 to Press against the bearing surface 3 side.
As a result, the spring foil 6 is deformed into a wave shape as shown in FIG. 4, and the comb teeth 7c,
Creates a undulation corresponding to the pitch of 8c. This undulation effectively acts on the gas film pressure generation mechanism.
Additionally, the thrust collar 1 deforms due to centrifugal force due to rotation or heat, but the bearing of the present invention
Since the structure has spring elements distributed in the rotational direction, it is possible to cope with such deformation of the thrust collar 1 without breaking the gas film. Furthermore, the bearing member 4 can be constructed by simply overlapping the foils 5, 7, 6, and 8 by aligning their mounting holes 5a, 7a, 6a, and 8a. The mounting holes 7a,
Since this problem can be solved by shifting the position of the bearing member 8a, assembly of the bearing member 4 is extremely simple, does not require skill, and can be performed accurately. Furthermore, the foils 5, 6, 7, and 8 can be easily manufactured by photoetching, precision pressing, or the like. The thrust gas bearing of the present invention is of the dynamic pressure type, and the thrust collar 1 and the topfoil 5 come into contact when the shaft starts and stops, so the bearing surface on the topfoil 5 improves wear resistance and sliding properties. Treatments such as coating have been applied.

In the above embodiment, the top oil 5 is used as a bearing surface member whose surface becomes a bearing surface.
is a spiral groove type with spiral groove 9, but tailing pad type,
Of course, the present invention can be easily applied to bearing surface members such as tapered land type and step type.

As is clear from the above explanation, the present invention exhibits the following excellent effects.

(1) Since the bearing member is constructed by simply overlapping the bearing surface member, the first comb-shaped oil, the spring foil, and the second comb-shaped oil,
Assembly is extremely easy.

(2) Furthermore, it is mass-producible, has high quality stability, and can reduce costs.

(3) Adjust the rigidity of the bearing member to the gas film pressure,
Since it can be formed distributed in the circumferential direction, bearing performance can be dramatically improved.

(4) Since the rigidity of the bearing can be determined by the thickness of the spring foil or the pitch between the teeth of the comb-shaped foil, the support rigidity and dimensional accuracy required for bearing design and manufacture can be easily satisfied.

(5) Since the bearing member has a structure in which spring elements are arranged in the circumferential direction, it can cope with thermal deformation of the thrust collar, etc., and has a high tolerance against the intrusion of dust.

[Brief explanation of drawings]

Fig. 1 is an explanatory diagram for explaining the assembly of the main parts of a conventional oil bearing, Fig. 2 is a plan view of a spring oil that constitutes the oil bearing, and Fig. 3 is an illustration of a thrust gas bearing according to the present invention. 4 is a circumferential sectional view showing an example of the bearing; FIG. 4 is a circumferential sectional view showing the operating state of the bearing; FIGS. 5 to 8 are views showing each component of the bearing member in FIG. 3. FIG. 5 is a plan view of the top oil, FIG. 6 is a plan view of the spring oil, and FIGS. 7 and 8 are plan views of the comb oil. In the figure, 1 is the thrust collar, 2 is the bearing case,
3 is a bearing surface, 4 is a bearing member, 5 is a top oil, 6 is a spring oil, 7, 8 are comb oils, 7c, 8c are comb teeth, 9 is a spiral groove, 5a, 6a, 7a, 8a are mounting holes, W is a This is a thrust load.

Claims (1)

[Scope of utility model registration request] In order to support the thrust load of the rotating shaft by forming a gas film on the outside of the thrust collar of the rotating shaft, a bearing case is provided on the outside of the thrust collar facing the rotating shaft, and a bearing surface of the bearing case surrounds the rotating shaft. In the gas thrust bearing, the bearing member has a bearing surface member provided on the thrust collar side and whose surface serves as a bearing surface, and a bearing surface member that acts on the bearing surface member. A spring oil is provided to elastically support and back up the gas film pressure from the supporting surface side, and the spring oil is sandwiched between the two surfaces of the spring oil, and the comb teeth along the radial direction of the rotating shaft are arranged around the rotating shaft. a first and a second comb-shaped foil each having a comb tooth row arranged radially at equal pitches along the direction, and the comb tooth rows of the first and second comb-shaped foils are shifted from each other. Displacement of the bearing surface member in the thickness direction of the bearing member when receiving the gas film pressure is caused by wave-shaped deformation of the spring oil along the circumferential direction of the rotating shaft. Thrust gas bearing structure.