JP2005061543A - Spiral offset bearing - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a spiral offset bearing having both of high flow rate and high load capacity. <P>SOLUTION: A cylindrical bearing face 2 surrounding a shaft main body 1 is composed of a plurality of circular arc faces 2a, 2b different from each other in their central axes, and spiral grooves 4 are formed in the circular arc faces 2a, 2b. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a sliding bearing, and is applied to, for example, a sliding bearing that is lubricated with a fluid passing through a pump used in a biological machine.

  An example of a sliding bearing and a sliding bearing device used as a bearing of a conventional rotating machine is shown in FIGS. FIG. 6 is disclosed in Japanese Patent Laid-Open No. 5-172141, and FIG. 7 is disclosed in Japanese Patent Laid-Open No. 5-187436.

  FIG. 6 will be described. A fixed shaft 102 is erected at the center of the housing 101, and a sleeve 103 is rotatably fitted to the fixed shaft 102 via a radial bearing clearance C1. A cylindrical radial bearing surface 104 is provided on the inner peripheral surface of the sleeve 103, and faces a radial receiving surface 105 provided on the outer peripheral surface of the fixed shaft 102. The radial bearing surface 104 is provided with a herringbone-shaped dynamic pressure generating groove 106 to constitute a radial fluid bearing R. On the other hand, the thrust bearing S is an attraction type magnetic bearing and is provided outside the sleeve 103. That is, a ring-shaped permanent magnet 107 is fixed to the lower end portion of the outer peripheral surface of the sleeve 103, and another ring-shaped permanent magnet 108 is positioned on the inner peripheral surface of the housing 101 and facing the permanent magnet 107. Is fixed. The outer peripheral surface of the permanent magnet 107 and the inner peripheral surface of the permanent magnet 108 are attracted to each other via a thrust bearing clearance C2.

  The sleeve 103 has a small flange 109 protruding on the outer peripheral surface, and a mirror 110 is fitted on the outer peripheral surface of the sleeve 103 on the flange 109. A case 113 to which the rotor 112 of the drive motor 111 is attached is fitted to the outer peripheral surface of the sleeve 103 under the flange 109. A stator coil 114 attached to the housing 101 is provided at a position facing the rotor 112 in the radial direction. A motor substrate 115 is installed below the stator coil 114.

  FIG. 7 will be described. This apparatus includes a base 116 that constitutes a motor casing. A coil substrate 117 is attached to the upper surface of the base 116 by a set bolt 118, and an iron core 119 and a coil 120 that constitute a motor are installed therein. A main shaft 121 is fixed to the center of the base 116 with a bottom nut 122, and a radial cylindrical portion 123 having a herringbone-shaped dynamic pressure generating groove 123a is provided on the outer periphery of the main shaft 121. A ring-shaped radial sleeve 124 constituting the rotating body R is rotatably provided on the outer periphery of the radial cylindrical portion 123. An upper thrust plate 125 and a lower thrust plate 126 are provided above and below the radial sleeve 124 so as to receive an axial thrust load of the rotating body R. Spiral dynamic pressure generating grooves 125a and 126a are formed on the surfaces of the upper and lower thrust plates 125 and 126 on the radial sleeve 124 side, respectively. Further, the radial cylindrical portion 123 and the upper and lower thrust plates 125 and 125 are fixed by an upper stopper nut 127.

  A ring-shaped yoke 128 is installed on the outer periphery of the lower portion of the radial sleeve 124, and a ring-shaped magnet 130a is attached to the inside of the ring portion 129 extending downward. On the upper side of the yoke 128, a rotor 130 having a polygonal planar shape from the outer peripheral surface and having a mirror surface M formed on the outer peripheral surface is located. An intermediate ring 131 is disposed between the radial sleeve 124 and the rotor 130. The intermediate ring 131 is fixed to the outer peripheral surface of the radial sleeve 124, and the rotor 130 is fixed to the intermediate ring 131. The rotor 130 and the intermediate ring 131 constitute an external rotating body.

  The two conventional sliding bearings and sliding bearing devices described above are a spiral bearing and a herringbone bearing in which a dynamic pressure generating groove having a spiral shape and a herringbone shape is formed on a bearing surface. Moreover, in the prior art of the offset bearing in a slide bearing, there exist some which are indicated by Japanese Utility Model Laid-Open No. 6-40442.

JP-A-5-172141 Japanese Patent Laid-Open No. 5-187436 Japanese Utility Model Publication No. 6-40442

  A sliding bearing used in such a rotating machine is required to have a bearing cooling performance, a foreign matter discharge performance, and a high load capacity. In particular, in the case of a self-lubricating (in this case, blood) bearing that is lubricated with a fluid passing through a pump, such as an artificial heart, in a living machine, these contents are indispensable. Cooling performance and foreign substance discharge performance are related to lubricity. Deterioration of lubricity in the pump in a biological machine causes blood to coagulate, so it passes through the bearings as well as preventing thrombus. It is necessary to increase the flow rate.

  However, in Patent Documents 1 and 2 described above, the flow rate through the bearing is improved by forming a dynamic pressure generating groove having a herringbone shape and a spiral shape on the bearing surface, but the improvement in load capacity is particularly improved. However, there is a problem that the bearing becomes unstable. In Patent Document 3, a high load capacity can be maintained by arranging the bearing surfaces having two different inner diameters offset with respect to the rotating shaft having a constant diameter. There is a problem in lubricity without improvement.

  Spiral bearings can earn a flow rate through the bearing, and offset bearings can earn a high load capacity. Therefore, an object of the present invention is to provide a spiral offset bearing having both a high flow rate and a high load capability.

  A spiral offset bearing according to a first aspect of the present invention for solving the above-mentioned problems is formed by forming a cylindrical bearing surface surrounding a shaft by a plurality of arc surfaces having different central axes, and forming a spiral groove on these arc surfaces. It is characterized by that.

  A spiral offset bearing according to a second aspect of the present invention for solving the above-described problems is formed by forming an outer peripheral surface of a shaft surrounded by a cylindrical bearing surface by a plurality of arc surfaces having different central axes, and spiraling around these arc surfaces. A groove is formed.

  As described above, according to the spiral offset bearing according to the present invention, the bearing surface is loaded with the load from the rotating shaft via the lubricant by offsetting the central axis of the rotating shaft with respect to the respective axes of the bearing surface formed of two arcs. It is possible to have a high load capacity because it can be received stably. Moreover, the amount of lubricant passing through the bearing is increased by forming the spiral groove on the bearing surface. Accordingly, lubricity, cooling performance, and foreign matter discharge performance are improved. Furthermore, the effect as described above can be obtained regardless of whether the bearing surface is formed on either the inner peripheral surface or the outer peripheral surface of the bearing.

  The spiral offset bearing according to the present invention will be described in detail based on examples.

Fig.1 (a) shows the front view of the spiral offset bearing of the 1st Embodiment of this invention, The same figure (b) shows the XX arrow longitudinal cross-sectional view. 2A to 2D are cross-sectional views taken along arrows AA to DD in FIG.

  A bearing body 1 that encloses the rotating shaft 3 has a cylindrical shape, and a bearing surface 2 is formed on the inner peripheral surface of the bearing body 1. The bearing surface 2 is formed by two circular arc surfaces including a bearing surface 2a having a radius Ra centered on the axis Oa and a bearing surface 2b having a radius Rb centered on the axis Ob. Although not shown, the space 2c surrounded by the bearing surfaces 2a and 2b is filled with a lubricant. The rotary shaft 3 is located in this space and is rotatably supported by the bearing surfaces 2a and 2b via a lubricant. The direction of rotation of the rotary shaft 3 is indicated by an arrow in the figure. A spiral groove 4 is spirally formed along the axial direction of the bearing body 1 from a position where the bearing surfaces 2a and 2b are in contact with each other.

With this configuration, the central axis O ₁ of the rotary shaft 3 is always offset with respect to the axis Oa of the bearing surface 2a and the axis Ob of 2b. As a result, when the rotating shaft 3 rotates, the lubricant flows into the narrower space in the gap between the bearing surfaces 2a and 2b and the rotating shaft 3. As a result, pressure is generated in the lubricant film as if a wedge was driven, and the bearing surfaces 2a and 2b can support the load received by the rotary shaft 3. The bearing surfaces 2a and 2b and the rotary shaft 3 are separated against the load received by the rotary shaft 3 and slip through the lubricant. Therefore, the bearing body 1 is stable and can obtain a high load capacity.

  Further, since the spiral groove 4 is provided, the lubricant is caught at the same time as the rotation shaft 3 rotates, so that more lubricant can pass through the gap between the bearing surfaces 2 a and 2 b and the rotation shaft 3. Accordingly, since a high flow rate of the lubricant can be maintained, not only the lubricity is improved, but also the bearing cooling property and the foreign matter discharging property are improved.

  FIG. 3A shows a front view of a spiral offset bearing according to a second embodiment of the present invention, and FIG. 3B shows a side view thereof. 4 (a) to 4 (d) are sectional views taken along arrows AA to DD in FIG. 3 (b).

  Although not shown, the space 5b surrounded by the inner peripheral surface 5a of the cylindrical rotating shaft 5 is filled with a lubricant. The fixed shaft 6 is located in the cylinder 5a and supports the rotating shaft 5 through this lubricant. The direction of rotation of the rotating shaft 5 is indicated by an arrow in the figure. That is, the surface of the fixed shaft 6 becomes the bearing surface 7. The bearing surface 7 is formed by two arc surfaces including a bearing surface 7a having a radius Rc centered on the axis Oc and a bearing surface 7b having a radius Rd centered on the axis Od. A spiral groove 8 is spirally formed along the axial direction of the fixed shaft 6 from a position where the bearing surfaces 7a and 7b are in contact with each other.

With this configuration, the central axis O ₂ of the rotating shaft 5 is always offset with respect to the axis Oc of the bearing surface 7a and the axis Od of the 7b. As a result, when the rotary shaft 5 rotates, the lubricant flows into the narrower space in the gap between the bearing surfaces 7a and 7b and the rotary shaft 5. As a result, pressure is generated in the lubricant film as if a wedge was driven, and the bearing surfaces 7a and 7b can support the load received by the rotary shaft 5. The bearing surfaces 7a and 7b and the rotary shaft 5 are separated from each other against the load received by the rotary shaft 5 and slip through the lubricant. Therefore, the fixed shaft 6 is stable and can obtain a high load capacity.

  Further, since the spiral groove 8 is provided, the lubricant is caught at the same time as the rotation shaft 5 rotates, and more lubricant can pass through the gap between the bearing surfaces 7a and 7b and the rotation shaft 5. Accordingly, since a high flow rate of the lubricant can be maintained, not only the lubricity is improved, but also the bearing cooling property and the foreign matter discharging property are improved.

  In the two embodiments described above, the offset surfaces that are the bearing surfaces are two, but a multi-arc having more than that may be used. Further, the twist angle of the spiral groove may be arbitrarily set depending on the number of rotations, the shaft length, the shaft diameter, and the like of the rotating shaft, and the shape of the groove depending on the set flow rate or flow velocity.

  FIG. 5 is a schematic cross-sectional view of an artificial heart pump using such a spiral offset bearing.

  A fixed shaft 10 is erected at the center of the housing 9. A rotating shaft 11 is positioned around the fixed shaft 10. The rotating shaft 11 is rotatably supported by the fixed shaft 10 through a bearing gap X. The outer peripheral surface of the fixed shaft 10 includes two arc surfaces, and the center axis of each arc surface is offset from the center axis of the inner surface of the rotating shaft 11. A spiral groove 10a is formed in a spiral shape on the surface of the fixed shaft 10 in the axial direction from the offset position of the offset arc surface. A magnet 12 is installed inside the rotating shaft 11. A stator coil 13 is installed inside the housing 9 adjacent to the rotating shaft 11 in the axial direction so as to oppose the magnet 12. A blade 14 is attached on the upstream side of the rotating shaft 11.

  The blood that has entered through the inflow port 15 flows to the discharge port 16 and is discharged by the blades 14 rotated by the rotation of the rotating shaft 11. This blood flow is indicated as A in the figure. However, some of the blood that has entered may flow to the center of the rotating shaft 11. This blood flow is indicated as B in the figure. The blood B flow that flows to the center of the rotating shaft 11 enters a bearing gap X that is a gap between the fixed shaft 10 and the rotating shaft 11. That is, the blood B flow enters the bearing gap X and becomes a lubricant.

  Since the axis of the inner peripheral surface of the rotary shaft 11 is offset with respect to the axes of the two arc surfaces forming the outer periphery of the fixed shaft 10, the blood that has entered the bearing gap X forms a film as a lubricant. Create pressure. As a result, the fixed shaft 10 supports the load received by the rotating shaft 11, and blood can smoothly pass along the spiral groove 10 a on the surface of the fixed shaft 10 by the rotation of the rotating shaft 11. .

  The blood that has passed through the bearing gap X flows through the gap between the surface 9a of the housing 9 orthogonal to the fixed shaft 10 and the end surface 11a on the downstream side of the rotating shaft 11. Thereafter, the housing 9 flows through a gap between a surface 9 b parallel to the fixed shaft 10 and the outer peripheral surface 11 b of the rotating shaft 11 and is discharged through the discharge port 15.

  By providing the spiral groove 10a in this way, the blood passing through the bearing gap X increases, which leads to improvement in lubricity and cooling performance. Moreover, since the flow does not stagnate, there is no fear of blood clotting, leading to the effect of preventing thrombus. In this embodiment, the spiral groove 10a is formed on the surface of the fixed shaft 10, but the same effect can be obtained even if it is formed on the inner peripheral surface 11c of the rotating shaft 11.

  The present invention is applied to a sliding bearing or the like that is lubricated with a fluid passing through a pump used in a biological machine or the like. It is particularly applicable to artificial heart pumps.

(A) It is a front view in the spiral offset bearing which shows the 1st Embodiment of this invention. (B) It is an XX arrow longitudinal cross-sectional view of the figure (a). It is each arrow sectional drawing from AA to DD in FIG.1 (b). (A) It is a front view in the spiral offset bearing which shows the 2nd Embodiment of this invention. (B) It is a side view of the same figure (a). It is each arrow sectional drawing from AA to DD in FIG.3 (b). It is a schematic sectional drawing of the artificial heart pump using the spiral offset bearing which concerns on embodiment of this invention. It is a schematic sectional drawing of an example of the conventional slide bearing apparatus. It is a schematic sectional drawing of an example of the conventional slide bearing.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Bearing body 2a, 2b Bearing surface 2c Space 3 Rotating shaft 4 Spiral groove 5 Rotating shaft 5a Inner peripheral surface 5b Space 6 Fixed shaft 7a, 7b Bearing surface 8 Spiral groove 9 Housing 10 Fixed shaft 11 Rotating shaft 12 Magnet 13 Coil 14 Blade 15 Inlet 16 Outlet

Claims (2)

  A spiral offset bearing characterized in that a cylindrical bearing surface surrounding a shaft is formed by a plurality of arc surfaces having different central axes, and a spiral groove is formed on these arc surfaces.   A spiral offset bearing characterized in that an outer peripheral surface of a shaft wrapped by a cylindrical bearing surface is formed by a plurality of arc surfaces having different central axes, and a spiral groove is formed on these arc surfaces.

Images