JPH0510529B2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to an elastic foil bearing structure having a shaft seal, and in particular, a structure in which the bearing and shaft seal are integrated by processing the front and back sides of a single foil material. This invention relates to a bearing structure that is simplified by simplifying the bearing structure.

[Prior Art] Conventionally, a hydrodynamic fluid bearing that has the function of supporting a rotating shaft and a hydrodynamic shaft seal that has the function of sealing the rotating shaft without contact have been constructed separately because their functions and structures are different. , nothing that has been unified yet exists. This is especially true for the foil bearing structure newly invented by the present inventor.

[Problems to be solved by the invention] Conventionally, the bearing and the shaft seal were separate parts.
The length of the rotating shaft in the axial direction becomes long, which hinders weight reduction and also causes a decrease in the rigidity of the rotating shaft, making it impossible to obtain sufficient speed and performance.

[Purpose of the invention] The present invention aims to provide a foil bearing structure with a shaft seal that can achieve greater speed and performance by integrating a bearing and a shaft seal to reduce size and weight, and increase the rigidity of the rotating shaft. That is.

[Summary of the Invention] The structure of the present invention in accordance with the above object is such that the bearing part and the shaft seal part are integrally provided adjacent to each other in the width direction of a single piece of elastic foil material. A bearing oil or seal oil part, a dump oil part, and a spring oil part, which are the elements of the shaft seal, are provided in parallel and in succession in order to form an elastic foil body with a shaft seal, and this elastic foil body with a shaft seal is connected to the rotating shaft. It is constructed by winding it in the above order in the gap between it and the supporting surface of the case, and stacking it in three layers. As a result, the bearing section generates fluid film pressure to support the shaft load, while the shaft seal section elastically displaces to seal the shaft.
It is designed to exhibit stable shaft function and shaft sealing function at high temperatures (low temperatures) and high speeds.

[Example] An example of the present invention will be described below based on FIGS. 1 to 4.

As shown in FIGS. 2A and 2D, a sheet of flexible elastic foil material is divided into a bearing part a and a shaft seal part b in the width direction. In the length direction, bearing part a
In the case of the shaft seal part b, it is a sectional view taken in the direction of arrow B.As shown in FIG. As shown in Figure C, a seal oil portion Lb, a damp oil portion Db, and a spring oil portion Sb are continuously formed. That is, by processing the front and back surfaces of a single sheet of foil material, an elastic foil body 1 is obtained in which a bearing portion a and a shaft seal portion b are integrally molded in parallel. The length of each part of this elastic foil body 1 corresponds to the circumferential length of a cylinder that goes around the case supporting surface, which will be described later, and the width is set to be the length necessary for shaft support and shaft sealing. Also, the bearing part a and the shaft seal part b
A plurality of ventilation holes 2, 2, . . . are bored at appropriate intervals in the length direction in the middle part in the width direction, which is divided into two parts, to equalize the pressure at both ends (width direction pressure) of the bearing part a.

The bearing foil part Ba of the bearing part a, which is divided in the width direction, is of a plain type with a flat inner surface as shown in Fig. 2 D, similar to the outer surface shown in Fig. 2 A, and this flat Appropriate wear-resistant treatment is applied to the inner surface. The type of bearing oil part Ba is not limited to the one shown in the illustration, but may include spiral groove, herringbone, step type,
Pocket type etc. are optional. Further, as shown in the figure, the bearing oil portion Ba has a plurality of pressure release passages 3 at appropriate intervals in the length direction at the center in the width direction for stabilizing high speed. This pressure release path 3 is a large diameter pocket 4 bored on the outer surface side.
and a small-diameter orifice 5 bored on the inner surface side, and the inner surface pressure is guided from the orifice 5 to the pocket 4 and released with a large force on the outer surface side.

A dump oil portion Da and a spring oil portion Sa, which are continuous with the bearing oil portion Ba, are provided on their outer surfaces across the entire length in the width direction and at appropriate intervals in the length direction (with shorter pitches than the above-mentioned release path 3). ) It has a plurality of linear support protrusions 6, 6, . . . that serve as spring elements formed therein. Dump oil section
The boundary between Da and the spring oil portion Sa is set to be 1.5 times the pitch b of the support protrusion 6. The outer surface end of the spring oil portion Sa has a key 7 for locking and fixing. Thus, the spring oil portion Sa and the damp oil portion Da have exactly the same shape except for the key 7.

On the other hand, the seal oil part Lb of the shaft seal part b divided in the width direction is the bearing oil part Ba.
Similarly, a plain type with a flat inner surface is illustrated, and in order to make the actual sealing surface narrower than the entire length in the width direction of the shaft seal portion b, both ends are shaved to form a convex cross-section. Appropriate anti-wear treatment is applied to the convex surface of this convex seal.

The dump oil portion Db and the spring oil portion Sb, which are continuous with the seal oil portion Lb, have ladder-like protrusions on their outer surfaces. That is, by forming a plurality of rectangular recesses 8, 8... having a predetermined depth at appropriate intervals in the length direction, the remaining parts 9, 10 at both ends in the width direction and the rectangular recesses are formed to ensure sealing performance. A ladder-like protrusion is formed by the linear support protrusion 11 remaining between the protrusions 8 and 8. The pitch of the linear support protrusion 11 of this ladder-like protrusion becomes a spring element like the support protrusion 6 of the bearing part a,
The pitch is larger than the pitch of the support projections 6 of the bearing part a, and the springiness is set relatively low. In the illustrated example, the width is set to twice that of the bearing portion a. Note that, unlike the case of the bearing part a, the outer surface end of the spring oil Sb of the shaft seal part b does not have a key that inhibits this in order to maintain sealing performance. The above-described processing of the foil surface can be carried out in one step by a known technique such as photoetching.

As shown in FIGS. 3 and 4, the elastic foil body 1 molded from the single foil material described above is assembled into a bearing foil part Ba, a sealing oil part Lb, a dump oil part Da, Db, and a spring foil part.
Sa and Sb are wound in this order and stacked between the rotating shaft 12 and the case support surface 13. That is, the elastic foil body 1 is formed into a triple-wound cylinder, and in the case of the bearing part a, as shown in FIG. 3, as shown in FIG.
Da and the spring oil part Sa are stacked one on top of the other in order, and the bearing oil part Ba is brought into close contact with the dump oil part Da, and the pressure release path 3 is placed between the support protrusions 6, 6 of the dump oil part Da.
The mutual positions of each part are adjusted so that the support protrusion 6 of the dump oil part Da is located between the support protrusions 6, 6 of the spring oil part Sa. By this adjustment, the shaft seal portion b is automatically stacked so that the support protrusion 11 of the dump oil portion Db is located between the support protrusions 11, 11 of the spring oil portion Sb, as shown in FIG.

Then, as shown in FIG.
A key groove 15 is provided in the axial direction by the width of the bearing part a, and the key 7 for locking and fixing the end of the bearing part is inserted into this key groove 15, and is pressed with the mounting plate 16 to secure the elastic foil body 1. A oil bearing structure with a shaft seal is constructed by restricting movement around the shaft and in the axial direction.

In this way, the oil bearing structure with a shaft seal of this embodiment has a bearing part a and a shaft seal part b having a three-layered oil structure, and between each layer a spring element, a damping element, a bearing element, and a sealing element are arranged on the case supporting surface. 13 are arranged in the circumferential direction.

Now, the operation of this embodiment with the above configuration will be explained.

The operating principle of the bearing and shaft seal of this embodiment is that the bearing part a supports the rotating shaft 12 by creating a bearing clearance by a function based on fluid lubrication in which the viscosity of the working fluid (gas or liquid) is dominant; The shaft seal part b is a non-contact type bearing/shaft seal that creates a shaft seal gap and seals while avoiding contact with the rotating shaft 12.

That is, when the shaft is eccentric in response to the magnitude of the shaft load, the bearing portion a of the elastic foil body 1 that supports the rotating shaft 12 will disturb the rotating shaft 12 and the bearing foil portion.
A wedge film is generated in the bearing gap Ga between Ba and a fluid film pressure, and this fluid film pressure supports the shaft load. By the way, when the rotating shaft 12 rotates at high speed, the fluid film pressure in the bearing gap Ga increases.

A part of this increased fluid film pressure is guided from the pressure release path 3 to the inner surface of the damp oil portion Da that is in close contact with the pressure release path 3, and is released therefrom. Since this pressure release is performed from the small diameter orifice 5 to the large diameter pocket 4, a large force acts radially outward on the inner surface of the dump oil portion Da, locally deforming the inner surface and causing the deformed local area. Forms a fluid reservoir. Therefore, a squeeze film damper action occurs in the damp oil portion Da to damp the shaft vibration. On the other hand, the unreleased pressurized fluid film pressure is
Since it acts on the entire circumference of the dump oil portion Da via Ba, the support protrusion 6 provided on the outer surface pushes the inner surface between the support protrusions 6, 6 of the spring oil portion Sa radially outward. For this reason, the spring oil portion Sa is deformed into a wave shape in the circumferential direction and exhibits a spring function. Therefore, the dump oil portion Da is elastically supported on the case support surface 13, allowing centrifugal deformation and thermal deformation of the shaft. In this way, in addition to the damping element and spring element due to the fluid film pressure itself, the damping function and spring function are exerted by the bearing part a of the foil laminated structure.
The rotating shaft 12 can be stably supported even at high speeds and high temperatures (low temperatures).

In addition, the shaft seal portion b of the elastic foil body 1 that seals the rotating shaft 12 is elastically displaced while forming a wedge film in response to the eccentricity of the rotating shaft 2, and comes into contact with the shaft seal portion b. Rotating axis 1 while avoiding
Seal 2. That is, unlike the case of the bearing part a where the recess between the support protrusions 6 and 6 is open in the width direction, the rectangular recess 8 of the shaft seal part b is closed in the width direction by the remaining parts 9 and 10 at both ends. Therefore, fluid pools originally exist in the rectangular recesses 8 of the dump oil portion Db and the spring oil portion Sa. Therefore, the rotating shaft 12 and the seal oil section
When pressurized fluid film pressure is generated in Gb in the seal gap between Gb and Lb and presses the seal oil part Lb radially outward, the spring oil part Sb undergoes wave-like deformation and exhibits a spring function. The fluid within the rectangular recesses 8, 8 is squeezed to create a squeeze membrane damper effect. Furthermore, the pitch of the support protrusion 11, which serves as the spring element of the shaft seal part b, is larger than that of the bearing part a, so that the springiness is set relatively low, so even if shaft vibration or shaft expansion occurs, the support projection 11 will not rotate. axis 12
It is possible to stably maintain an extremely small seal gap without contacting the seal. The shaft seal part b in the illustrated example is simply a clearance seal of a cylindrical surface seal, and in this case, the leakage amount equivalent to the sealing performance is proportional to the differential pressure and is inversely proportional to the cube of the seal gap. , being able to maintain an extremely small seal gap means that the sealing performance is significantly improved. In this way, the damping function and spring function of the shaft seal part b of the foil laminated structure are exhibited in addition to the function of the fluid film pressure, so stable sealing performance without contact or clinging is achieved even at high speeds and high temperatures (low temperatures). can be obtained.

As described above, according to this embodiment, the above-mentioned bearing part a and shaft seal part b are formed from a single piece of foil material, and the surface of the material is processed in one step by a known technique such as photo etching. Therefore, it is mass-producible and can be manufactured at a very low cost. When assembling, if it is triple-wound and inserted between the rotating shaft 12 and the case support surface 13, it will expand due to the springiness of the elastic foil body 1 itself and the spring foil portion Sa,
Sb comes into tight contact with the case support surface 13, and the other foil parts are also automatically adjusted in circumferential position accordingly, eliminating the need to individually adjust the position of laminated foils, and assembling. Work becomes extremely easy.

Furthermore, since the assembled bearing structure is a foil structure, it is small and lightweight, and can exhibit stable bearing and shaft sealing functions even at high speeds and high temperatures (low temperatures). Therefore, high efficiency can be obtained especially when applied to high-speed rotating turbomachines such as turbo compressors, turbo expanders, turbochargers, and turbo refrigerators that use high-temperature or low-temperature gas as a process fluid.

The foil structure also has the secondary effect of being resistant to foreign matter intrusion.

5 and 6 show a modification of the embodiment shown in FIG. 1 in which the shaft seal portion b is of a plain type with a simple cylindrical surface, and the sealing surface is machined with a plurality of grooves. That is, the one in Fig. 5 has a plurality of spiral grooves 18 carved at equal intervals in the length direction on the seal convex surface of the seal oil part Lb, and the one in Fig. 6 has a seal oil part Lb.
Rather, a spiral groove 18 is carved into the rotating shaft 12 of the seal portion, and the pumping action of the spiral groove 18 enhances the sealing effect. spiral groove 18
It is desirable to design the direction by determining the high pressure side, low pressure side, and rotation direction, and in the illustrated example, P ₁ > P ₂
The figure shows the case where the rotating shaft 12 rotates as indicated by the arrow.

According to this, when the rotary shaft 12 rotates, fluid tries to flow from P ₁ to P ₂ across the seal portion due to the differential pressure, but due to the pumping action of the spill groove 18, the fluid on the low pressure P ₂ side is transferred to the high pressure P The function of transferring to _{the 1st} side is demonstrated, and the sealing performance can be actively improved. In particular, since the pumping action increases as the speed increases, the sealing effect at high speeds is significant.

Note that in the case of P ₂ > P ₁ , although not shown,
The spiral groove 18 may be provided in the opposite direction to that shown in FIGS. 5 and 6, and the land portion 19 may be provided at the opposite end.

[Effects of the Invention] In summary, the present invention exhibits the following excellent effects.

(1) Since the bearing part and the shaft seal part are integrated into a single piece of elastic foil, the fixed side can be made smaller and lighter, and the axial length of the rotating shaft can be shortened. It is also possible to reduce the weight on the rotating side and improve rigidity. Therefore, the speed and performance of rotating machinery can be significantly increased.

(2) By using a foil structure for the bearing part and shaft seal part, it can sufficiently cope with the centrifugal expansion and thermal expansion of the rotating shaft, and even if the gap is designed to be small, contact and clinging, which were common problems in the past, will not occur. It can function stably and safely at high temperatures (low temperatures) and high speeds without any problems.

[Brief explanation of the drawing]

FIG. 1 is a side sectional view, partially unfolded, showing a preferred embodiment of the oil bearing structure with a shaft seal according to the present invention, and FIG. 2 is a circumferential view of the elastic foil body, which is the main part of FIG. 3 is a sectional view taken in the direction of the arrows in FIG. 1, and is a front sectional view of the bearing portion; FIG. 6 and 6 are side sectional views showing a modified example of the present invention, including a partially expanded state. In the figure, 1 is an elastic foil body, 3 is a pressure release path,
12 is the rotating shaft, 13 is the case support surface, a is the bearing part, b is the shaft seal part, Ba is the bearing oil part, Da is the dump oil part, Sa is the spring oil part, Lb is the seal oil part, and Db is the seal oil part. The dump oil part and Sb are the spring oil part.

Claims (1)

[Claims] 1. A bearing oil section that forms a fluid film pressure and has a pressure release path that releases the fluid film pressure, a damp oil section that receives the fluid film pressure released from the pressure release path and damps vibrations, and elastically supports the dump oil section. An elastic foil bearing part in which a spring oil part is formed in sequence, a seal oil part that forms a fluid film pressure, a damp oil part that dampens vibration of the seal oil part, and a spring oil part that elastically supports the dump oil part are successively formed. With a shaft seal, characterized in that an elastic foil body formed by integrally molding the formed elastic foil shaft seal portion in parallel is wound and laminated between the rotating shaft and the case support surface in the above continuous formation order. Oil bearing structure.