JP5026200B2 - Multi-layer foil bearing assembly - Google Patents

Description

  The present invention relates to a multilayer foil bearing assembly used for supporting a crankshaft of an engine, a main shaft of a turbo machine, or the like.

  Generally, a metal bearing is used as a bearing for supporting a crankshaft of an automobile engine. Although the use of a rolling bearing is conceivable, the rolling bearing is not expected to be attenuated due to the squeeze effect of the oil film because the rolling element and the race are in point contact or line contact. On the other hand, the metal bearing has a large oil film attenuation and can be operated quieter than the rolling bearing.

  In addition, sliding bearings such as metal bearings are often used as bearings for supporting the main shaft of a turbomachine such as a gas turbine. However, since the turbomachine main shaft rotates at a high speed and the torque loss is large when it is a sliding bearing, the use of a rolling bearing or an air foil bearing (for example, Patent Document 1) has been studied.

As a slide bearing for a shaft that rotates at high speed, a research on a floating bush type in which a bush is held in a floating state via a fluid with respect to a shaft and a housing has been studied, but has not been put into practical use. The reason is that, as the calculation result is shown in Non-Patent Document 1, the floating bush type bearing cannot provide the expected effect.
JP 2003-262222 A Nobutaka Hamada "Bearing" Iwanami Shoten Co., Ltd., July 10, 1970, p267

  When the crankshaft bearing is a metal bearing, there are the following problems. In other words, since the oil film is not formed when the engine is started, the metal bearing is prone to wear when the idling stop is frequently used, and the torque loss due to the viscous resistance of the oil film during high speed rotation is large. In order to improve the fuel efficiency of automobiles, it is necessary to suppress this torque loss. If only the torque loss is suppressed, a rolling bearing may be used, but the rolling bearing has the above-mentioned drawbacks. Therefore, development of a sliding bearing with less torque loss in place of a metal bearing is desired. Fortunately, in the case of a crankshaft bearing, it is not necessary to divide the housing into two parts for incorporation at both ends of the crankshaft, so it is easy to introduce a sliding bearing other than a metal bearing.

  Further, when the bearing for the turbomachine main shaft is a rolling bearing or an air foil bearing, there are the following problems. That is, the rolling bearing has a problem of quietness and rolling fatigue life, and the air foil bearing has a problem of wear when starting and stopping.

  An object of the present invention is to provide a multilayer foil bearing assembly suitable for supporting an engine crankshaft, a main shaft of a turbo machine, etc., capable of performing a quiet operation, having little torque loss and little wear during starting and stopping. Is to provide.

In the multilayer foil bearing assembly according to the present invention, a plurality of cylindrical foils having different diameters are provided in the radial direction between a shaft and a housing having an inner peripheral surface facing the outer peripheral surface of the shaft. And the oil film is formed between the foils, between the innermost foil and the outer peripheral surface of the shaft, and between the outermost foil and the inner peripheral surface of the housing, thereby forming an oil film. is supported in a non-contact to the inner layer of the foil, each foil to each other is supported in a non-contact, the outermost layer of the foil is supported without contact to the housing, the wall thickness of the foil Ri der less 0.5 mm, the foil Means is provided for causing the lubricating oil to flow into the center in the foil width direction of the gap between the foils by rotation .

  According to this configuration, when the shaft rotates, it slips between the foils, through the oil film made of lubricating oil formed between the innermost foil and the outer peripheral surface of the shaft, and between the outermost foil and the inner peripheral surface of the housing. Occurs. If the conditions of each oil film are the same, the slipping speed is inversely proportional to the number of foil layers, so the more the number of layers, the smaller the slipping speed in each layer. Therefore, by providing the foil in multiple layers, the viscous resistance of the oil film can be lowered and the loss of bearing torque can be suppressed.

The thickness of the foil is below 0.5mm or less, and even better preferably be from 0.02 mm 0.1 mm.
The reason why the floating bush type sliding bearing is not as effective as expected is because the thickness of the floating bush is large, and the performance can be improved by making the foil as thin as 0.5 mm or less. . Further, by reducing the thickness of the foil, it is possible to increase the number of foil layers without increasing the diameter of the bearing portion.

The means for causing the lubricating oil to flow into the center side in the foil width direction of the gap between the foils is a dynamic pressure groove provided on the surface of the foil, and the dynamic pressure groove is a width direction of the foil. It should be symmetrical with respect to the center .
When the dynamic pressure groove is provided on the surface of the foil, the lubricating oil gathers in the axial center of the foil during the operation of the bearing, and between the foils, between the innermost foil and the outer peripheral surface of the shaft, and the outermost layer. Lubricating oil can be sufficiently retained between the foil and the inner peripheral surface of the housing.

It is preferable that the foil has elasticity that can be deformed to such an extent that it can be inserted into the inner diameter side of the central portion of the inner peripheral surface without causing interference with both ends of the inner peripheral surface of the housing.
If the foil can be inserted into the inner diameter side of the central portion of the inner peripheral surface of the housing using its own elasticity, the assembly of the bearing becomes easy.

The portion of the shaft that faces the central portion of the inner peripheral surface of the housing may have a larger diameter than other portions of the shaft.
In this case, because of the pumping action accompanying the rotation of the shaft, the lubricating oil is sent into the space surrounded by the outer peripheral surface of the shaft, the central portion of the inner peripheral surface of the housing, and the stepped surface portion of the inner peripheral surface of the housing. A sufficient amount of lubricating oil can be secured in the space.

The housing is provided with a lubricating oil supply hole for supplying lubricating oil into a space surrounded by the outer peripheral surface of the shaft, the central portion of the inner peripheral surface of the housing, and the stepped surface portion of the inner peripheral surface of the housing. May be.
In this case, a sufficient amount of lubricating oil can be secured in the space by forcibly supplying the lubricating oil into the space from the lubricating oil supply hole.

  The foil bearing of the present invention can be suitably used for supporting a crankshaft of an engine or a main shaft of a turbomachine because the above-described action is obtained.

In the multilayer foil bearing assembly according to the present invention, a plurality of cylindrical foils having different diameters are provided with a radial gap between a shaft and a housing having an inner peripheral surface facing the outer peripheral surface of the shaft. And forming an oil film between the foils, between the innermost foil and the outer peripheral surface of the shaft, and between the outermost foil and the inner peripheral surface of the housing, thereby forming an oil film, so that the shaft becomes the innermost layer. is supported in a non-contact manner of the foil, each foil to each other is supported in a non-contact, the outermost layer of the foil is supported without contact to the housing, the wall thickness of the foil Ri der below 0.5 mm, the rotation of the foil due to the provision of a means for creating an action flowing the lubricating oil toward the center of the foil width of the gap between the foil makes it possible to perform a quiet operation, small torque loss, start and stop time of wear ho No etc. does. Therefore, it is suitable for supporting the crankshaft of an engine, the main shaft of a turbo machine and the like.

  A first embodiment of the present invention will be described with reference to FIGS. FIG. 1 shows a cross-sectional view of the multilayer foil bearing assembly of this embodiment. This multilayer foil bearing assembly 1 supports the shaft 3 rotatably with respect to the housing 2, and has a plurality of cylindrical foils 5 to 9 having different diameters as the multilayer foil bearing portion 4. In this embodiment, the number of foils is five. Each of the foils 5 to 9 is disposed between the inner periphery of the housing 2 and the outer periphery of the shaft 3 with a gap in the radial direction. Between each foil 5-9, between the innermost foil 5 and the outer peripheral surface 3a of the shaft 3, and between the outermost foil 9 and the inner peripheral surface 2a of the housing 2, oil film forming gaps 10 are formed. Lubricating oil is retained.

  The foils 5 to 9 are thin metal plates that do not exceed 0.5 mm in thickness, and are easily deformed and have elasticity that can be restored to their original shapes. The thickness of the foils 5 to 9 is preferably 0.02 mm to 0.1 mm. As the material of the foils 5 to 9, high yield stress is required. For example, carbon steel whose yield stress is improved by work hardening by quenching, or a material with high yield stress such as phosphor bronze is suitable. In addition, those having a wear-resistant resin coating and those having a hard film typified by diamond-like carbon (DLC) can be suitably used. Furthermore, the foils 5 to 9 do not have to be made of the same metal material, and foils of different metals may be alternately arranged.

  As shown in FIGS. 2 and 3, a large number of dynamic pressure grooves 13 are provided in parallel on the surfaces of the foils 5 to 9. The dynamic pressure groove 13 includes a pair of left and right inclined grooves 13L and 13R. The left and right inclinations 13 </ b> L and 13 </ b> R have an angle α with respect to the rotation direction of the foil 5. FIG. 3 illustrates the dynamic pressure groove 13 of the foil 5. As the shaft 3 rotates, the dynamic pressure groove 13 causes the oil film forming gap 10 to hold the lubricating oil by pumping the lubricating oil into the center by the pair of left and right inclined grooves 13L and 13R, and the oil film pressure is increased. Acts to generate. Various design values such as the width, depth, and angle α of the hydrodynamic groove 13 can be easily calculated based on the design of the hydrodynamic bearing.

In this embodiment, the dynamic pressure grooves 13 are arranged at equal intervals, and the width of the dynamic pressure grooves 13 and the width of the back portion between the dynamic pressure grooves 13 are the same. You may arrange with.
When the rotation direction of the shaft 3 is one direction, as shown in FIG. 3, the dynamic pressure groove 13 is best composed of a pair of inclined grooves 13L and 13R. However, when it is incorporated in reverse, its performance cannot be exhibited. Therefore, as shown in FIG. 4, the forward rotation dynamic pressure groove forming portion 14A and the reverse rotation dynamic pressure groove forming portion 14B, each consisting of a pair of left and right inclined grooves 13L and 13R, are arranged on the surfaces of the foils 5-9. It is preferable to provide them alternately in the direction or the width direction.

  For the production of the foils 5 to 9, plastic working such as deep drawing is suitable. Deep drawing enables high-precision machining on the order of microns. As described above, since the foils 5 to 9 are as thin as 0.5 mm or less, cutting is not applicable. Even if it can, it will be expensive. As a foil manufacturing method other than plastic working, a method of plating a required thickness with a metal as a foil material on the surface of a cylindrical mold made of a low melting alloy and then melting and removing the mold can be used. As the cylindrical mold material, fats and oils may be used instead of the low melting alloy. It is also possible to finely adjust the diameter by rolling the finished foil. The dynamic pressure groove 13 is formed, for example, by plastic working after the outer shapes of the foils 5 to 9 are manufactured by the above methods.

  In assembling the multilayer foil bearing assembly 1, the foils 5 to 9 are assembled in the housing 2, and then the shaft 3 is inserted into the inner periphery of the innermost foil 5. When assembling the foils 5 to 9 in the housing 2, as shown by the solid line in FIG. 5, the foils 5 to 9 are deformed by utilizing the elasticity of the foils 5 to 9, and the flange 2b of the housing 2 is passed through. It is incorporated inside the portion 2b in the axial direction. That is, each of the foils 5 to 9 has elasticity that can be deformed to such an extent that it can be inserted into the inner diameter side of the inner peripheral surface central portion 2aa without interfering with both end portions 2ab of the inner peripheral surface of the housing 2. As shown by the chain line in the figure, after being incorporated, the foils 5 to 9 are naturally restored to the original shape. FIG. 5 shows the outermost foil 9.

  According to the multilayer foil bearing assembly 1 of this configuration, since the lubricating oil is held in each oil film forming gap 10 to form an oil film, the shaft 3 is supported by the innermost foil 5 in a non-contact manner, and the innermost layer is formed. The shaft 5 is supported by the housing 2 via the multiple layers of foils 5 to 9 such that the foil 5 is supported in a non-contact manner by the outer foil 6. The sliding speed of the shaft 3 that occurs during the rotation of the shaft 3 decreases in proportion to the number of layers of the foils 5 to 9. Torque loss is proportional to sliding speed. Therefore, by making the foils 5 to 9 multilayer, the viscous resistance of the oil film can be lowered and the torque can be reduced. Moreover, if the clearance amount of each oil film formation clearance 10 is the same, it will increase in proportion to the number of layers of foil 5-9. For this reason, even if there is a weight imbalance around the axis of the shaft 3, vibration is suppressed.

  Since the dynamic pressure grooves 13L and 13R are provided on the surfaces of the foils 5 to 9, the oil film can sufficiently hold the lubricating oil in the oil film forming gap 10 when the shaft 3 is rotated, and enables an oil-free support. Pressure is generated. Moreover, the part which comprises the foil accommodating space 11 of the shaft outer peripheral surface 3a becomes a large diameter part 3aa having a larger diameter than the others, and the part between the large diameter part 3aa and the normal diameter part 3ab becomes a tapered part 3ac. Therefore, as the shaft 3 rotates, the lubricating oil flows into the foil housing space 11 through the lubricating oil inflow passage 12 as shown by the arrow in FIG. 1 due to the pumping action of the tapered portion 3ac. For this reason, a sufficient amount of lubricating oil can be secured in the foil accommodating space 11.

  Since the foils 5 to 9 are thin, the radial dimension of the multilayer foil bearing portion 4 does not increase even if the foil is multilayered. For this reason, the multilayer foil bearing assembly 1 can be miniaturized. Further, the foils 5 to 9 can be manufactured at a low cost by deep drawing. For this reason, the multilayer foil bearing assembly 1 can be reduced in price.

Next, a second embodiment shown in FIG. 6 will be described. This 2nd Embodiment is an example corresponding to the multilayer foil bearing assembly 1 with a wide axial direction width | variety. When the axial width is wide, the lubricating oil tends to be insufficient at the axial central portion of each oil film forming gap 10. Therefore, in this multilayer foil bearing assembly 1, a communication hole 15 is provided in the central portion in the axial direction of each of the foils 5 to 9 to communicate the inner peripheral side and the outer peripheral side. In this embodiment, the communication holes 15 are provided at two positions located at equal intervals in the circumferential direction, but the number of the communication holes 15 is not limited to two. Furthermore, a lubricating oil supply hole 16 is provided in the central portion of the housing 2 in the axial direction, and lubricating oil sent from a lubricating oil supply device (not shown) is introduced into the foil accommodating space 11 from the lubricating oil supply hole 16. Supplied. A circumferential groove 17 that guides the lubricating oil supplied from the lubricating oil supply hole 16 in the circumferential direction in the foil housing space 11 is formed on the inner peripheral surface of the housing 2 connected to the inner diameter side end of the lubricating oil supply hole 16. ing.
In the second embodiment, unlike the first embodiment, the shaft 3 has the same diameter over the entire area. Further, the inclined surface portion is not provided between the both end portions 2ab and the step surface portion 2ac on the inner peripheral surface 2a of the housing 2. Others are the same as the first embodiment.

  With the configuration of the second embodiment, the lubricating oil is forcibly supplied into the foil housing space 11 from the lubricating oil supply hole 16, and the lubricating oil passes through the circumferential groove 17 to communicate with the outermost foil 9. From the hole 15, the oil film forming gap 10 between the outermost foil 9 and the inner foil 8 is supplied to the central portion in the axial direction. Similarly, lubricating oil is sequentially supplied to the axially central portion of the inner oil film forming gap 10. For this reason, the lack of lubricating oil at the axially central portion of each oil film forming gap 10 can be resolved.

  The usage example of the multilayer foil bearing assembly 1 of this invention is shown. FIG. 7 shows an example in which the multilayer foil bearing assembly 1 of the first embodiment is applied to a bearing that supports both ends of the crankshaft 20 of the engine. The crankshaft 20 includes a rotation center shaft 21, a balance weight 22, and a crank pin 23, and both end portions of the rotation center shaft 21 are rotatably supported by the multilayer foil bearing assembly 1. In this case, the rotation center shaft 21 corresponds to the shaft 3 in the multilayer foil bearing assembly 1. The crank pin 23 is rotatably supported by a bearing 25 at one end 24 a of the connecting rod 24. The multi-layer foil bearing assembly 1 may be applied to the bearing 25 as well.

  FIG. 8 shows an example in which the multilayer foil bearing assembly 1 of the second embodiment is applied to a bearing that supports a main shaft 31 of a micro gas turbine that is a kind of turbomachine. In the micro gas turbine, air is compressed by an air compressor 32, fuel is combusted by a combustor 33 using the compressed air, and the moving blades of the turbine 34 are rotated by high-temperature and high-pressure combustion gas generated thereby. Thus, electric power is obtained by the generator 35. The obtained electric power is output via the inverter 36. Further, the heat of the compressed air sent from the air compressor 32 to the combustor 33 and the heat of the combustion gas exiting the turbine 34 are recovered by the heat recovery device 37 to make the water warm.

  The main shaft 31 is a shaft in which the turbine impellers of the air compressor 32 and the turbine 34 are attached to both ends. The main shaft 31 is attached to the housing 38 by the multilayer foil bearing assembly 1 at a plurality of axial positions (two in this embodiment). It is supported rotatably. In this case, the main shaft 33 corresponds to the shaft 3 in the multilayer foil bearing assembly 1, and the housing 38 corresponds to the housing 2 in the multilayer foil bearing assembly 1.

  As described above, the multilayer foil bearing assembly 1 of the present invention is suitable for a bearing portion that supports both ends of the crankshaft 20 of the engine and a bearing portion that supports the main shaft 31 of a turbo machine such as a micro gas turbine. It can be applied to other bearings.

It is sectional drawing of the multilayer foil bearing assembly concerning 1st Embodiment of this invention. It is the elements on larger scale of FIG. It is a development view of the foil surface. It is an expanded view of the surface of a different foil. It is explanatory drawing which shows the incorporating method of foil. It is sectional drawing of the multilayer foil bearing assembly concerning 2nd Embodiment of this invention. It is a partial cross section figure of the crankshaft of the engine incorporating the multilayer foil bearing assembly of a 1st embodiment. It is sectional drawing of the turbomachine incorporating the multilayer foil bearing assembly of 2nd Embodiment.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Multi-layer foil bearing assembly 2 ... Housing 2a ... Housing inner peripheral surface 3 ... Shaft 3a ... Shaft outer peripheral surface 5-9 ... Foil 10 ... Oil film formation clearance 13 ... Dynamic pressure groove 20 ... Crank shaft 21 ... Rotation center shaft 31 ... Main shaft 38 ... housing

Claims (3)

A plurality of cylindrical foils having different diameters are arranged between the shaft and a housing having an inner peripheral surface opposite to the outer peripheral surface of the shaft, with a gap in the radial direction between each foil. By forming an oil film between the outer foil of the shaft and the outer peripheral surface of the shaft and between the outermost foil and the inner peripheral surface of the housing to form an oil film, the shaft is supported in a non-contact manner by the innermost foil. foil each other is supported in a non-contact, the outermost layer of the foil is supported without contact to the housing, the wall thickness of the foil Ri der below 0.5 mm, gaps between the foils the lubricating oil by the rotation of the foil A multilayer foil bearing assembly comprising means for causing an action of flowing toward the center in the foil width direction . In claim 1, the means for causing the lubricating oil to flow into the center side in the foil width direction of the gap between the foils is a dynamic pressure groove provided on the surface of the foil, A multilayer foil bearing assembly having a symmetrical shape with respect to the center in the width direction of the foil.   3. The multilayer foil bearing assembly according to claim 1, wherein the multilayer foil bearing assembly is used for supporting a crankshaft of an engine or a main shaft of a turbomachine.

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