JPS6347520A - Foil journal bearing - Google Patents

Abstract

PURPOSE:To eliminate a key and a key way and simplify the structure while reduce the cost of the captioned bearing by rolling up an resilient foil having linear projections on its back in many layers and bringing said foil into pressure contact with the removably supporting face of a bearing case due to the outward spring resilience in the radial direction of said foil itself. CONSTITUTION:A machined and molded resilient foil 4 is rolled up utilizing its resiliency and inserted into a bearing case 1 and, when it is released, the foil 4 is brought into pressure contact with a removably supporting face 2 due to its outward spring resiliency in the radial direction and assembled. And, the upper layer serves as a bearing foil part 7, the middle layer as a dump foil part 8, and the lower layer as a spring foil part 9 and, normally, a wear resistant coating is given to the bearing foil part 7. Also a stopper is provided to prevent a multiple layer foil 3 from projecting out of the bearing case 1 in the radial direction. Thus, since a key is not used for stopping and fixing, a simple bush can serve as the bearing case, and the structure as well as assembling can be made very simple.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to a hydrodynamic foil journal bearing using a liquid or gas as a lubricant, and in particular is an improvement of a multi-wound continuous foil for practical use. It has great advantages when applied to high-speed turbo machinery such as turbochargers, turbo expansion turbines, fuel cell turbo compressors, and turbo refrigerators.

[Prior Art] Conventional technology for journal bearings using continuous multi-wound foils includes a bearing foil section, a dump foil section, and a spring foil section, as shown in Japanese Patent Laid-Open No. 61-74910, for example. Continuously integrated processing,
There is one in which this is triple-wound on the bearing surface of the bearing case, and a key attached to the end of the lowest layer spring foil is locked and fixed in the keyway of the bearing case.

However, this method requires welding to attach the key to the end of the spring foil part, and it also requires a keyway to be provided in the bearing case, resulting in high costs.Moreover, it is difficult to align the key and keyway during assembly. Work is required. Also, the bearing function is lost in the key part.

[Problems to be Solved by the Invention] As mentioned above, the conventional method requires a key and a keyway to lock and fix the foil to the bearing case, which makes processing and assembly troublesome and increases the cost, making mass production difficult. The problem was that I wasn't suitable for sex.

Therefore, an object of the present invention is to solve the above conventional problems by eliminating keys and keyways, and to provide a foil journal bearing that has a simple structure, is easy to process and assemble, and can be mass-produced at low cost. It is to provide.

[Means for Solving the Problems] The foil journal bearing of the present invention includes a bush-shaped bearing case whose entire bearing surface is smooth, and a bearing surface of the bearing case that is pressed against the bearing surface by the spring elasticity of the foil itself outward in the radial direction. The multilayer foil is composed of a long elastic foil, and the multilayer foil is provided with a plurality of linear protrusions extending across the back surface of the long elastic foil at an appropriate mwA in the longitudinal direction, and at least excluding the ends of the foil. When the elastic foil provided with linear protrusions is wound multiple times so that its back surface faces outward in the radial direction and is brought into pressure contact with the bearing surface, the linear protrusions of the elastic foil on the radially outward side The elastic foils are stacked so that the linear protrusions of the elastic foils are located between them in the radial direction.

[Function] To assemble a foil journal bearing, an elastic foil provided with linear protrusions is wound in multiple layers so that its back surface faces outward in the radial direction, and the diameter of the foil is larger than the inner diameter of the bearing surface of the bearing case. Multilayer foil in a reduced diameter state. When the multilayer foil is inserted into the bearing case and released, the multilayer foil expands due to its radially outward spring elasticity and is automatically pressed against the bearing surface. In the above insertion, the method of locking and fixing to the bearing surface with a key is not used, but a pressure welding method using spring elasticity against the smooth bearing surface is used, so that the circumferential positioning of the bearing case and the multilayer foil is easy. No longer needed.

In addition, since there is no linear protrusion at the end of the foil, the end of the outermost foil contacts the bearing surface with a gentle slope without creating a step between it and the bearing surface. The elastic foil that rides on the part is also smoothly laminated.

The foil journal bearing assembled in this way is
By positioning the linear protrusions of the radially inward elastic foil between the linear protrusions of the radially outward elastic foil, the springs acting in the radial direction are distributed over the entire circumference and have a spring function. Furthermore, since a squeeze film is formed in the space formed between the linear protrusions, it also has a squeeze damper function. Furthermore, the coulomb between the elastic foils of each layer constituting the multilayer foil! ! ! Friction damping capability is also added.

These spring functions, squeeze damper functions, and Coulomb friction functions are particularly effective during high-speed rotation to prevent self-excited imaging from occurring.

[Example] An example of the present invention will be described below based on FIGS. 1 to 9.

Figure 1 is an assembled sectional view of the foil journal bearing.
It consists of a bush-shaped bearing case 1 and a multilayer foil 3 pressed against the bearing surface 2 of the bush-shaped bearing case 1. Bearing case 1
The entire bearing surface 2 of is a completely smooth surface and has no grooves.

The multilayer foil 3 is constructed by winding a single long elastic foil 4 with a width L1 and a length n+1)πD in multiple layers. One side of the elastic foil 4 is processed by photo-etching or the like as shown in FIG.

That is, it is processed so that it has a large number of linear protrusions 5 integrally at intervals of pitch p, avoiding the foil ends.

The length of this linear projection portion is nπD, where D is the bearing inner diameter. n is an integer and n≧2, and in Figure 1, n
-2 case is shown as an example. Continuing from the linear protrusion processed portion, the unprocessed portion has a length πD and a thickness t). That is, a plain bearing in which the foil portion (bearing foil portion) of the bearing surface 6 is flat is illustrated.

As shown in FIG. 3, the linear projections are formed by processing one side of the elastic foil 4 having a thickness t to have a width β, a pitch (length) p, and a depth δ. Although the pitchle 1 thickness t, the processing depth δ, and the number of turns n are arbitrary, the spring properties and damping properties of the foil bearing are determined by these values. In particular, the processing depth δ of the foil is important because it becomes the squeeze film itself, and should be selected to the depth that will allow the squeeze film to perform its function.

Note that the pitch p is not necessarily constant over the entire length.

The elastic foil 4 processed and formed as described above is wrapped around it using its elasticity and inserted into the bearing case 1.
The support surface 2 is pressed against the support surface 2 by the elastic force of the spring outward in the radial direction and assembled as shown in FIG.

The upper layer is the bearing foil section 7, the middle layer is the dump foil section 8, and the lower layer is the spring foil section 9. Usually, the bearing foil portion 7 is coated with a wear-resistant coating. Further, it is desirable to provide a stopper (not shown) as appropriate to prevent the multilayer foil 3 from protruding from the bearing case 1 in the axial direction. Note that 10 is a journal which rotates in the direction of the arrow.

11 is a fluid fJ slide, and 12 is a squeeze film.

By the way, in the case of a foil journal bearing as shown in FIG. 1, which has a key groove in the bearing case 1 and in which a key attached to the final end of the multilayer foil 3 is fixedly locked, Although there are various problems as mentioned above,
In this example, since such locking and fixing is not performed using a key, the above-mentioned effect is achieved, and the bearing case is also a simple bushing, resulting in a very simple structure and extremely easy assembly. .

Further, since the bearing surface 6 of the bearing foil portion 7 does not need to be deformed into a spiral group shape or a herringbone shape, and is a plain bearing, processing of the elastic foil becomes very easy.

Further, the bearing constructed in this manner is of a type that enables high-speed stability, and springs and dampers are distributed radially outward of the bearing foil portion 7 over the entire circumference.

The spring action is determined by a multi-layer structure of continuous holes with a span of width p and a height of 1 δ). The damper action is achieved by the squeezing effect of a fluid film (gas or liquid) and the Coulomb friction effect.

The factors that influence the function of this squeeze effect are (p-j ratio, L, δ, and number of turns n, but as already mentioned, the value of the fluid film depth δ is particularly important. In other words, the fluid film depth δ of the bearing It is necessary to determine the squeeze film δ that matches the film pressure and the spring constant of the foil, and usually δ is several μm to several tens of μm.

Note that Coulomb ffl friction occurs at the contact portions of the linear protrusions 5 arranged in large numbers.

By having the above-mentioned functions, it is possible to prevent the occurrence of self-excited vibrations that are likely to occur at high speed rotation, achieve ultra-high speed stabilization, and achieve high efficiency mainly when applied to turbo machines.

It also has a high tolerance to foreign matter intrusion, and is particularly applicable to high-temperature and low-temperature gas bearings.

4 and 5 show modifications of the embodiment shown in FIGS. 1 and 2, and the difference from FIGS. 1 and 2 is that linear protrusions 5 are provided over the entire length of the elastic foil 4. The bearing foil portion 7a, including the bearing foil portion 7a, is machined to a quality of nπD. In this case as well, processing is performed to avoid the linear protrusions 5 from coming to both ends of the elastic foil 4, but the foil end 14 of the bearing foil portion 7a does not have the same problem as the foil end 13 of the spring foil portion. Therefore, there is no problem even if the linear protrusion 5 comes to the foil end 14 of the bearing foil portion 7a.

FIG. 4 exemplifies the case where n=3, and it may function as a multi-arc bearing during high-speed rotation.

Moreover, FIGS. 6, 7, 8, and 9 show modifications of the embodiments shown in FIGS. 1, 2, 4, and 5, respectively, and the differences from these are as follows. Bearing foil part 7
, 7a, damping orifices 15 are provided at appropriate intervals in the longitudinal direction of the bearing surface 6.6a, and as a result, part of the fluid film pressure is released, the generation of negative pressure, etc. is eliminated, and further stabilization is achieved. This has the advantage of being able to

[Effects of the Invention] To summarize, according to the present invention, a bush-shaped bearing case and an elastic foil having linear protrusions on the back surface excluding at least the foil end are wound in multiple layers, and the elastic foil is wound in the radial direction of itself. It consists of a multilayer foil that is pressed against the bearing surface of the bearing case by an external spring force, and the key is removed from the foil end and the keyway is removed from the bearing case, resulting in a simple structure. Processing and assembly are easy, and costs can be reduced.

Additionally, there is no need to align the bearing case and the multilayer foil in the circumferential direction, and the multilayer foil is not locked and fixed.
Since it is simply pressed against the bearing surface by its own spring elasticity, it has excellent high speed, stability, and reproducibility, and it is possible to produce m.

[Brief explanation of the drawing]

Fig. 1 is an assembled sectional view of a foil journal bearing according to an embodiment of the present invention, Fig. 2 is an exploded perspective view of the elastic foil shown in Fig. 1, and Fig. 3 is a processing of the linear protrusion shown in Fig. 2. FIG. 4 is an assembled sectional view of a foil journal bearing showing another embodiment; FIG. 5 is an exploded perspective view of the elastic foil shown in FIG. 4; FIG. 1
7 is an exploded perspective view of the elastic foil shown in FIG. 6, FIG. 8 is an assembled sectional view of the foil journal bearing showing a modification of FIG. 4, FIG. 9 is an exploded perspective view of the elastic foil shown in FIG. 8. In the figure, 1 is a bearing case, 2 is a bearing surface, 3 is a multilayer foil, 4 is an elastic foil, 5 is a linear projection, 7° 7a is a bearing foil portion, and 15 is a damping orifice. Patent applicant: Ishikawajima-Harima Heavy Industries Co., Ltd. Patent attorney: Nobuo Kinuya Figure 1: 4° Archery Figure 2: Figure 3: Figure 4: Figure 6

Claims (4)

[Claims] (1) A bush-shaped bearing case with a smooth entire bearing surface,
The multilayer foil is pressed against the bearing surface of the bearing case by the spring elasticity of the foil itself in the radial direction, and the multilayer foil has a linear protrusion extending longitudinally across the back surface of the long elastic foil. A large number of foils are integrally provided at appropriate intervals, and at least except for the foil ends,
When the elastic foil provided with linear protrusions is wound multiple times so that its back surface faces outward in the radial direction and is brought into pressure contact with the bearing surface, the linear protrusions on the elastic foil on the radially outward side are A foil journal bearing characterized in that the elastic foils are stacked so that the linear protrusions are located on the radially inward side. (2) The bearing according to claim 1, wherein the linear protrusion is provided except for the bearing foil portion which is the uppermost layer of the multilayer foil. (3) A patent claim characterized in that orifices for releasing part of the fluid film pressure on the bearing surface are bored at appropriate intervals in the longitudinal direction in the bearing foil portion which is the uppermost layer of the multilayer foil. A bearing according to any one of ranges 1 to 2. (4) The bearing according to any one of claims 1 to 3, wherein the elastic foil is provided with a stopper that prevents the elastic foil from protruding in the axial direction from the bearing case. .