JP2017166598A - Journal bearing - Google Patents

Abstract

PROBLEM TO BE SOLVED: To restrain a decrease in bearing stability even if a bearing gap becomes small.SOLUTION: A journal bearing comprises a concave part 7 in a portion of a bearing inner peripheral surface 1a facing a rotating shaft outer peripheral surface.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a journal bearing.

  For example, in the journal pad bearing device described in Patent Document 1, the curvature of the back surface of the pad is divided into a plurality of pads that are arranged on the inner peripheral surface of the bearing pedestal and the back surface contacting the inner peripheral surface is a cylindrical surface or a spherical surface. Is set to be 0.85 times to 0.9 times the curvature of the inner peripheral surface of the bearing pedestal.

  Further, for example, a tilting pad type journal bearing described in Patent Document 2 is a journal bearing in which a rotating shaft is supported by a plurality of tilting pads disposed in a bearing housing. Is formed smaller than the radius of curvature of the inner surface of the bearing housing, and the radius of curvature of the inner surface of the tilting pad is larger than the radius of curvature of the rotating shaft.

Japanese Utility Model Publication No. 62-60723 Japanese Utility Model Publication No. 3-69713

  By the way, since the journal bearing supports the rotating shaft by an oil film of lubricating oil between the bearing inner peripheral surface and the rotating shaft outer peripheral surface, the bearing clearance between the bearing inner peripheral surface and the rotating shaft outer peripheral surface, In relation to the ratio to the peripheral surface radius (bearing clearance ratio = bearing clearance / bearing internal peripheral surface radius), the behavior of the rotating shaft based on the bearing rigidity (K), which is the rigidity with which the journal bearing supports the rotating shaft, and the lubricant. The relationship Cω / K with the bearing attenuation (Cω) that attenuates the pressure changes. Specifically, when the bearing clearance ratio decreases, the bearing damping (Cω) and the bearing rigidity (K) increase, and when the bearing clearance ratio increases, the bearing attenuation (Cω) and the bearing rigidity (K) decrease. The magnitude relationship of Cω / K changes depending on the effect of bearing damping (Cω) and bearing stiffness (K). When Cω / K increases, the stability of the bearing that supports the rotating shaft increases, and vibration of the rotating shaft is suppressed. The effect tends to be high, and when Cω / K becomes small, the bearing stability becomes low and the effect of suppressing the vibration of the rotating shaft tends to be low.

  As a result of the test, there is an event in which the vibration of the bearing rotating shaft increases as the rotating shaft approaches the inner peripheral surface of the bearing and the bearing clearance becomes smaller. In this event, the smaller the bearing clearance, the higher the hardness of the lubricating oil film, the greater the load applied to the bearing and the greater the bearing stiffness (K), the smaller Cω / K and the lower the bearing stability. It is thought that there is.

  The present invention solves the above-described problems, and an object of the present invention is to provide a journal bearing that can suppress a decrease in bearing stability even when the bearing gap is reduced.

  In order to achieve the above-mentioned object, a journal bearing according to an aspect of the present invention is characterized by having a recess in a part of the bearing inner peripheral surface facing the outer peripheral surface of the rotating shaft.

  In the journal bearing according to one aspect of the present invention, the inner circumferential surface of the bearing is formed with a constant circumferential curvature, and the inner surface of the concave portion is formed with a constant circumferential curvature, It is preferable that the curvature of the inner surface is different from the curvature of the inner peripheral surface of the bearing.

  In the journal bearing according to one aspect of the present invention, the circumferential curvature xa of the outer peripheral surface of the rotating shaft, the circumferential curvature xb of the concave portion, and the circumferential curvature xc of the inner peripheral surface of the bearing are: It is preferable to satisfy the relationship of xa <xb <xc.

  In the journal bearing according to one aspect of the present invention, it is preferable that the maximum depth e of the inner surface of the recess and the diameter r of the rotating shaft satisfy a relationship of 0.003 ≦ e / r ≦ 0.007. .

  Further, the journal bearing according to one aspect of the present invention includes a plurality of pads divided in the circumferential direction, the circumferential length θw of the inner circumferential surface of the bearing in one pad, and the circumference of the recess in one pad. It is preferable that the direction length β satisfies the relationship of 0.5 ≦ β / θw ≦ 0.8.

  Further, in the journal bearing according to an aspect of the present invention, the bearing includes a plurality of pads divided in the circumferential direction, and the bearing inner circumferential surface of one pad is formed with a constant curvature in the circumferential direction, and the inner surface of the concave portion Is preferably formed with a constant curvature in the circumferential direction, and the center line of the arc length of the inner surface of the recess coincides with the center line of the arc length of the inner peripheral surface of the bearing.

  Further, in the journal bearing according to an aspect of the present invention, the bearing includes a plurality of pads divided in the circumferential direction, and the bearing inner circumferential surface of one pad is formed with a constant curvature in the circumferential direction, and the inner surface of the concave portion Is formed with a constant curvature in the circumferential direction, and the center line of the arc length of the inner surface of the recess is different from the center line of the arc length of the inner peripheral surface of the bearing, and the center line of the arc length of the inner surface of the recess Is preferably arranged so as to be shifted forward in the rotational direction of the rotary shaft with respect to the arc length center line of the bearing inner peripheral surface.

  Moreover, in the journal bearing which concerns on 1 aspect of this invention, it is preferable that the said recessed part is provided without hooking on the edge of the said bearing internal peripheral surface.

  Moreover, in the journal bearing which concerns on 1 aspect of this invention, it is preferable that the said recessed part is provided in the lower half part of the circumferential direction.

  According to the present invention, it is possible to suppress a decrease in bearing stability even when the bearing gap is reduced.

FIG. 1 is a schematic configuration diagram of a journal bearing according to an embodiment of the present invention. FIG. 2 is a detailed configuration diagram of the journal bearing according to the embodiment of the present invention. FIG. 3 is a detailed configuration diagram of another example of the journal bearing according to the embodiment of the present invention. FIG. 4 is a detailed configuration diagram of another example of the journal bearing according to the embodiment of the present invention. FIG. 5 is a detailed configuration diagram of another example of the journal bearing according to the embodiment of the present invention. FIG. 6 is a detailed configuration diagram of another example of the journal bearing according to the embodiment of the present invention.

  Embodiments according to the present invention will be described below in detail with reference to the drawings. In addition, this invention is not limited by this embodiment. In addition, constituent elements in the following embodiments include those that can be easily replaced by those skilled in the art or those that are substantially the same.

  FIG. 1 is a schematic configuration diagram of a journal bearing according to the present embodiment. 2A and 2B are detailed configuration diagrams of the journal bearing according to the embodiment of the present invention, in which FIG. 2A is a side view and FIG. 2B is a plan view.

  As shown in FIG. 1, since the journal bearing 1 of this embodiment supports the rotating shaft 3 rotatably, the bearing inner peripheral surface 1a faces the rotating shaft outer peripheral surface 3a of the rotating shaft, and the bearing gap B therebetween. It forms a lubricating oil film. For this reason, the journal bearing 1 has a bearing outer peripheral surface 1 b fixed to the inner peripheral surface 5 a of the inner ring 5. Further, the journal bearing 1 of the present embodiment is composed of a pad divided into a plurality (four in the present embodiment) in the circumferential direction that is the rotational direction of the rotating shaft 3.

  As shown in FIG. 2, the journal bearing 1 of the present embodiment has a recess 7 in a part of the bearing inner peripheral surface 1a. The concave portion 7 is a portion that is recessed radially outward (from the bearing outer peripheral surface 1b side) from the bearing inner peripheral surface 1a and does not penetrate to the bearing outer peripheral surface 1b side.

  In the journal bearing having no recess 7, when the rotary shaft 3 approaches the journal bearing, the bearing gap between the rotary shaft outer peripheral surface 3a and the bearing inner peripheral surface is reduced, and the hardness of the lubricating oil film is high. The load applied to the journal bearing is increased, the bearing rigidity (K), which is the rigidity with which the journal bearing supports the rotating shaft 3, becomes excessive, and the bearing damping (Cω) that attenuates the behavior of the rotating shaft 3 based on lubricating oil. The relationship Cω / K becomes smaller and the bearing stability becomes lower.

  On the other hand, according to the journal bearing 1 of the present embodiment having the recess 7, the load capacity of the journal bearing 1 is reduced by having the recess 7, so that the rotary shaft 3 sinks to the bearing inner peripheral surface 1 a side. Therefore, the bearing clearance ratio on the inner circumferential surface 1a of the bearing is smaller even in a load state equivalent to that of the journal bearing having no recess 7. In the concave portion 7, pressure that resists the lubricating oil being pushed out by the outer peripheral surface 3 a of the rotating shaft is generated (referred to as a squeeze effect), and the bearing damping (Cω) is increased by this generated pressure, while the concave portion 7 The bearing rigidity (K) increase is small because the load is equivalent to that of a journal bearing without a bearing. That is, the journal bearing 1 of the present embodiment has high bearing stability because Cω / K increases under the same operating conditions as the journal bearing without the recess 7. As a result, it is possible to suppress a decrease in bearing stability even when the bearing gap is reduced.

  Note that, as shown in FIG. 2, the recess 7 is formed so that both sides in the circumferential direction, which is the rotation direction of the rotary shaft 3, gradually approach the bearing inner circumferential surface 1 a due to the inclination and are connected. It is preferable to obtain the above significantly.

  Further, in the journal bearing 1 of the present embodiment, as shown in FIG. 2, the circumferential curvature is constant with the bearing inner circumferential surface 1 a as the center Oa and the inner surface of the concave portion 7 is the center Ob. It is preferable that the curvature of the inner surface of the recess 7 is different from the curvature of the bearing inner peripheral surface 1a.

  According to the journal bearing 1, a squeeze effect can be sufficiently obtained by forming a constant curvature in the circumferential direction of the bearing inner peripheral surface 1 a and a constant curvature in the circumferential direction of the inner surface of the recess 7. Since the damping (Cω) can be increased, the bearing stability can be increased by increasing Cω / K.

  In the journal bearing 1 of the present embodiment, the circumferential curvature xa of the rotating shaft outer circumferential surface 3a, the circumferential curvature xb of the concave portion 7, and the circumferential curvature xc of the bearing inner circumferential surface 1a are xa <. It is preferable to satisfy the relationship of xb <xc.

  According to this journal bearing 1, by satisfying the relationship of curvature of xa <xb <xc, the lubricating oil can easily enter the recess 7 during the rotation of the rotating shaft 3, and a sufficient squeeze effect is obtained to obtain bearing damping (Cω ) Can be increased, and Cω / K can be increased to increase bearing stability.

  In the journal bearing 1 of the present embodiment, it is preferable that the maximum depth e of the inner surface of the recess 7 and the diameter r of the rotating shaft 3 satisfy the relationship of 0.003 ≦ e / r ≦ 0.007. When the diameter r of the rotating shaft 3 is 300 mm, the maximum depth e of the inner surface of the recess 7 is about 1 mm to 2 mm.

  According to this journal bearing 1, when e / r is set to 0.003 or more, the lubricating oil easily enters the recess 7 during the rotation of the rotary shaft 3, and by setting it to 0.007 or less, a sufficient squeeze effect is obtained. Can be obtained. As a result, bearing damping (Cω) can be increased, and Cω / K can be increased to increase bearing stability.

  Further, the journal bearing 1 of the present embodiment is composed of a plurality of pads divided in the circumferential direction. As shown in FIG. 2, the circumferential length (arc length) θw of the bearing inner circumferential surface 1a in one pad is It is preferable that the circumferential length (arc length) β of the recess 7 in one pad satisfies the relationship of 0.5 ≦ β / θw ≦ 0.8.

  According to this journal bearing 1, by defining the range of the recess 7 and the range of the bearing inner peripheral surface 1a as described above, the normal bearing function of the journal bearing 1 by the bearing inner peripheral surface 1a and the rotation by the recess 7 are achieved. It is possible to achieve both a function of suppressing a decrease in bearing stability when the shaft 3 approaches and the bearing clearance B between the rotary shaft outer peripheral surface 3a and the bearing inner peripheral surface 1a becomes small.

  Further, in the journal bearing 1 of the present embodiment, as shown in FIG. 1, it is composed of a plurality of pads divided in the circumferential direction, and the bearing inner circumferential surface 1a in one pad is formed with a constant curvature in the circumferential direction, The inner surface of the recess 7 is formed with a constant circumferential curvature, and as shown in FIG. 2, the center line CL2 of the arc length of the inner surface of the recess 7 coincides with the center line CL1 of the arc length of the bearing inner peripheral surface 1a. It is preferable to do.

  According to this journal bearing 1, the center lines CL 1 and CL 2 can be formed in one pad by matching the center line CL 1 of the arc length of the bearing inner peripheral surface 1 a with the center line CL 2 of the arc length of the inner surface of the recess 7. On average, the normal bearing function of the journal bearing 1 by the bearing inner peripheral surface 1a and the rotating shaft 3 by the recess 7 approach and the bearing clearance B between the rotating shaft outer peripheral surface 3a and the bearing inner peripheral surface 1a is small. In this case, it is possible to achieve both a function of suppressing a decrease in bearing stability in the event of failure.

  3 and 4 are detailed configuration diagrams of other examples of the journal bearing according to the present embodiment.

  In the journal bearing 1 according to the present embodiment, as shown in FIG. 1, the bearing inner peripheral surface 1 a of one pad is formed with a constant curvature in the circumferential direction, and includes a plurality of circumferentially divided pads. 7 is formed with a constant curvature in the circumferential direction, and as shown in FIGS. 3 and 4, the center line CL2 of the arc length of the inner surface of the recess 7 is the center line CL1 of the arc length of the bearing inner peripheral surface 1a. And the position may be different. In this case, as shown in FIG. 3, the center line CL2 of the arc length of the inner surface of the recess 7 is shifted from the center line CL1 of the arc length of the bearing inner peripheral surface 1a to the front in the rotational direction R of the rotary shaft 3. It is preferable that

  According to this journal bearing 1, in rotation of the rotary shaft 3, the oil film pressure by the lubricating oil is relatively high behind (upstream side) the recess 7 in the bearing inner peripheral surface 1a, and the recess 7 in the bearing inner peripheral surface 1a The oil film pressure by the lubricating oil is relatively low in the front (downstream side). Therefore, if the center line CL2 of the arc length of the inner surface of the recess 7 is arranged to be shifted forward in the rotation direction R of the rotating shaft 3 with respect to the arc center line CL1 of the bearing inner peripheral surface 1a, Since the area of the bearing inner peripheral surface 1a where the oil film pressure by the lubricating oil is relatively high in the rear (upstream side) is widened, the bearing damping (Cω) can be increased, and Cω / K can be increased to increase the bearing stability. Can be high. In addition, the load capacity of the journal bearing 1 can be maintained by improving the rigidity by increasing the area of the bearing inner peripheral surface 1a where the oil film pressure by the lubricating oil is relatively high behind the recess 7 (upstream side).

  FIG. 5 is a detailed configuration diagram of another example of the journal bearing according to the present embodiment. FIG. 5 (a) is a side view, FIG. 5 (b) is a plan view, and FIG. 5 (c) is a longitudinal sectional view. is there.

  In the journal bearing 1 of this embodiment, as shown in FIG. 5, it is preferable that the recess 7 is provided so as not to hang over the edge 1c of the bearing inner peripheral surface 1a. The edge 1c is an end in the axial direction (thrust direction) where the rotating shaft 3 extends on the bearing inner peripheral surface 1a. That is, it is preferable that the bearing inner peripheral surface 1 a exists around the entire periphery of the recess 7.

  According to this journal bearing 1, since the bearing inner peripheral surface 1 a exists around the entire periphery of the recess 7, a squeeze effect can be obtained around the entire periphery of the recess 7 to increase bearing damping (Cω). The bearing stability can be increased by increasing / K.

  FIG. 6 is a detailed configuration diagram of another example of the journal bearing according to the present embodiment, in which FIG. 6A is a side view and FIG. 6B is a plan view.

  As shown in FIG. 6, in the journal bearing 1 of the present embodiment, the circumferential length (arc length) β of the recess 7 is provided in the range of the circumferential length (arc length) θω of the bearing inner peripheral surface 1a. May be. Even with this configuration, the squeeze effect can be obtained to increase the bearing damping (Cω), and Cω / K can be increased to increase the bearing stability.

  Moreover, in the journal bearing 1 of this embodiment, as shown in FIG. 1, it is preferable that the recessed part 7 is provided in the lower half part (below the horizontal line H) of the circumferential direction.

  According to this journal bearing 1, since the rotating shaft 3 approaches the bearing inner peripheral surface 1a of the lower half of the journal bearing 1 by gravity, the recess 7 is provided in the lower half, thereby obtaining a squeeze effect and damping the bearing. Since (Cω) can be increased, Cω / K can be increased to increase bearing stability.

  By the way, although not explicitly shown in the drawing, the journal bearing 1 is not limited to a configuration including a plurality of pads, and may be formed in a ring shape continuously in the circumferential direction. In this case, the concave portion 7 may be formed in a ring shape continuously in the circumferential direction or may be partially formed in the circumferential direction.

DESCRIPTION OF SYMBOLS 1 Journal bearing 1a Bearing inner peripheral surface 1b Bearing outer peripheral surface 3 Rotating shaft 3a Rotating shaft outer peripheral surface 5 Inner ring 5a Inner peripheral surface 7 Recessed part B Bearing gap CL1, CL2 Center line H Horizontal line Oa, Ob Center R Rotating direction r Diameter xa, xb , Xc Curvature β, θω Circumferential length

Claims (9)

  A journal bearing having a recess in a part of an inner peripheral surface of a bearing facing an outer peripheral surface of a rotating shaft.   The inner peripheral surface of the bearing is formed with a constant curvature in the circumferential direction, and the inner surface of the recess is formed with a constant curvature in the circumferential direction, and the curvature of the inner surface of the recess and the curvature of the inner peripheral surface of the bearing are The journal bearing according to claim 1, which is different.   The circumferential curvature xa of the rotating shaft outer peripheral surface, the circumferential curvature xb of the concave portion, and the circumferential curvature xc of the bearing inner peripheral surface satisfy a relationship of xa <xb <xc. Or the journal bearing of 2.   4. The journal bearing according to claim 1, wherein a maximum depth e of the inner surface of the recess and a diameter r of the rotating shaft satisfy a relationship of 0.003 ≦ e / r ≦ 0.007. 5. .   It consists of a plurality of pads divided in the circumferential direction, and the circumferential length θw of the bearing inner circumferential surface in one pad and the circumferential length β of the concave portion in one pad are 0.5 ≦ β / θw The journal bearing according to claim 1, wherein the journal bearing satisfies a relationship of ≦ 0.8.   It consists of a plurality of pads divided in the circumferential direction, the bearing inner peripheral surface in one pad is formed with a constant circumferential curvature, and the inner surface of the recess is formed with a constant circumferential curvature, The journal bearing according to any one of claims 1 to 5, wherein a center line of the arc length of the inner surface of the recess coincides with a center line of the arc length of the inner peripheral surface of the bearing.   It consists of a plurality of pads divided in the circumferential direction, the bearing inner peripheral surface in one pad is formed with a constant circumferential curvature, and the inner surface of the recess is formed with a constant circumferential curvature, The center line of the arc length of the inner surface of the concave portion is different from the center line of the arc length of the inner peripheral surface of the bearing, and the center line of the arc length of the inner surface of the concave portion is the center line of the arc length of the inner peripheral surface of the bearing. The journal bearing according to any one of 1 to 5, wherein the journal bearing is arranged to be shifted forward in the rotational direction of the rotary shaft.   The journal bearing according to any one of claims 1 to 7, wherein the concave portion is provided so as not to hang on an edge of the inner peripheral surface of the bearing.   The journal bearing according to any one of claims 1 to 8, wherein the concave portion is provided in a lower half portion in a circumferential direction.

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