JP2019218972A

JP2019218972A - Main bearing for crank shaft of internal combustion engine, and bearing device

Info

Publication number: JP2019218972A
Application number: JP2018114977A
Authority: JP
Inventors: 志歩後藤; Shiho GOTO; 斉藤　康志; Koji Saito; 康志斉藤
Original assignee: Daido Metal Co Ltd
Current assignee: Daido Metal Co Ltd
Priority date: 2018-06-15
Filing date: 2018-06-15
Publication date: 2019-12-26

Abstract

To provide a main bearing for a crank shaft of an internal combustion engine having a function for discharging foreign matters included in a lubricant, and excellent in supply of the oil to a sliding surface.SOLUTION: A main bearing has first and second half-split bearings, and has an axial groove at an inner peripheral surface side of a butting part of the first and second half-split bearings. The first half-split bearing has an oil groove extended in a circumferential direction on its inner peripheral surface, and the second half-split bearing has a partial groove extended in a circumferential direction on its inner peripheral surface. A peripheral end portion at a front side in a rotating direction of the crank shaft, of the oil groove, and a peripheral end portion at a rear side in the rotating direction of the crank shaft, of the partial groove are separated by a first circumferential distance, and the first circumferential distance is smaller than a circumferential length of an inlet opening of a lubricant passage formed in a journal portion of the crank shaft, thus the oil groove is fluid-communicated with the axial groove and the partial groove, or the partial groove through the lubricant passage.SELECTED DRAWING: Figure 2

Description

本発明は、内燃機関のクランク軸用主軸受に関するものであり、より詳細には、クランク軸のジャーナル部を内燃機関のシリンダブロック下部に支持するための主軸受に関するものである。さらに本発明は、そのような主軸受および対応する軸部から構成される軸受装置にも関するものである。 The present invention relates to a main bearing for a crankshaft of an internal combustion engine, and more particularly to a main bearing for supporting a journal portion of a crankshaft under a cylinder block of an internal combustion engine. The invention further relates to a bearing device comprising such a main bearing and a corresponding shaft.

内燃機関のクランク軸は、そのジャーナル部において、一対の半割軸受から成る主軸受を介して内燃機関のシリンダブロック下部に支持される。この主軸受を潤滑するために、オイルポンプによって吐出された潤滑油が、シリンダブロックの壁内に形成されたオイルギャラリーおよび主軸受の壁に形成された貫通口を通して、主軸受の内周面に沿って形成された潤滑油溝内に送り込まれる。クランク軸には、第１潤滑油路がジャーナル部を直径方向に貫通して形成されており、その両端開口で主軸受の潤滑油溝と連通する。さらに、第２潤滑油路が第１潤滑油路から分岐してクランクアーム部を通るように形成され、クランクピンの直径方向に貫通して形成された第３潤滑油路と連通している。したがって、主軸受の潤滑油溝内に送り込まれた潤滑油は、第１潤滑油路、第２潤滑油路および第３潤滑油路を通り、その後、第３潤滑油路の端部開口（クランクピンの外周面上に形成される潤滑油出口）からクランクピンとコンロッド軸受の間の摺動面に供給される。 The crankshaft of the internal combustion engine is supported at its journal portion below the cylinder block of the internal combustion engine via a main bearing composed of a pair of half bearings. In order to lubricate the main bearing, the lubricating oil discharged by the oil pump is applied to the inner peripheral surface of the main bearing through an oil gallery formed in the cylinder block wall and a through hole formed in the main bearing wall. It is fed into the lubricating oil groove formed along. A first lubricating oil passage is formed in the crankshaft so as to penetrate the journal portion in the diametrical direction, and communicates with the lubricating oil groove of the main bearing at both ends thereof. Further, the second lubricating oil passage is formed so as to branch off from the first lubricating oil passage and pass through the crank arm portion, and communicates with a third lubricating oil passage formed to penetrate in a diametrical direction of the crankpin. Therefore, the lubricating oil fed into the lubricating oil groove of the main bearing passes through the first lubricating oil passage, the second lubricating oil passage, and the third lubricating oil passage, and thereafter, the end opening (crank) of the third lubricating oil passage. The lubricating oil outlet formed on the outer peripheral surface of the pin) supplies the sliding surface between the crankpin and the connecting rod bearing.

主軸受の潤滑油溝は、一対の半割軸受のうちの少なくとも一方の内周面に、その周方向の全長に亘って形成される（特許文献１の図１）。この場合、シリンダブロック内のオイルギャラリーから主軸受の潤滑油溝に供給された潤滑油は、ジャーナル部の回転にしたがって半割軸受の周方向端部まで主として流れ、その多くが、一対の半割軸受の接合部に形成された軸線方向溝を通して軸受外部に排出される（特許文献１、２参照）。 The lubricating oil groove of the main bearing is formed on the inner peripheral surface of at least one of the pair of half bearings over the entire length in the circumferential direction (FIG. 1 of Patent Document 1). In this case, the lubricating oil supplied from the oil gallery in the cylinder block to the lubricating oil groove of the main bearing mainly flows to the circumferential end of the half bearing according to the rotation of the journal portion, and most of the lubricating oil flows in a pair of the half. It is discharged to the outside of the bearing through an axial groove formed at the joint of the bearing (see Patent Documents 1 and 2).

さらに、近年では、内燃機関の低燃費化を目的とする潤滑油供給用オイルポンプの小型化に対応して、半割軸受の周方向端部からの潤滑油の漏れ量を減少させるために、潤滑油溝の周方向長さが半割軸受の周方向全長よりも短く構成され、したがって潤滑油溝の周方向両端部の少なくとも一方が半割軸受の周方向端部まで延びていない（軸線方向溝で開口していない）主軸受も用いられている。この主軸受では、一対の半割軸受の接合部に形成された軸線方向溝と潤滑油溝の周方向端部とを、ジャーナル部の外周面上に形成された、ジャーナル部の内部に延びる潤滑油路の入口開口を介して周期的に連通させ、それにより潤滑油溝内の潤滑油中に含まれる異物は、軸線方向溝に流れ、該軸線方向溝を通して軸受外部に排出される（特許文献３参照）。 Furthermore, in recent years, in order to reduce the amount of leakage of lubricating oil from the circumferential end of the half bearing, corresponding to the miniaturization of the lubricating oil supply oil pump for the purpose of reducing the fuel consumption of the internal combustion engine, The circumferential length of the lubricating oil groove is configured to be shorter than the entire circumferential length of the half bearing, so that at least one of the circumferential ends of the lubricating oil groove does not extend to the circumferential end of the half bearing (axial direction). Main bearings (not open in grooves) are also used. In this main bearing, the axial groove formed at the joint between the pair of half bearings and the circumferential end of the lubricating oil groove are formed on the outer peripheral surface of the journal portion by the lubrication extending into the journal portion. The foreign matter contained in the lubricating oil in the lubricating oil groove flows through the axial groove and is discharged to the outside of the bearing through the axial groove. 3).

特開平８−２７７８３１号公報JP-A-8-277831 特開２００５−６９２８３号公報JP 2005-69283 A 特開２０１３−１２４７６５号公報JP 2013-124765 A

シリンダブロック内のオイルギャラリーから主軸受およびクランク軸の内部潤滑油路を経てコンロッド軸受に送られる潤滑油は、例えば各部品の加工の際に生じた残留異物を随伴する可能性がある。この異物は、ジャーナル部と主軸受の間の摺動面およびクランクピンとコンロッド軸受の間の摺動面に損傷を与える恐れがあり、したがって潤滑油の流れから速やかに外部に排出する必要がある。 The lubricating oil sent from the oil gallery in the cylinder block to the connecting rod bearing via the internal lubricating oil passages of the main bearing and the crankshaft may be accompanied by, for example, residual foreign matter generated during processing of each part. This foreign matter may damage the sliding surface between the journal portion and the main bearing and the sliding surface between the crankpin and the connecting rod bearing. Therefore, it is necessary to quickly discharge the lubricant from the flow of the lubricating oil to the outside.

一対の半割軸受の接合部に軸線方向溝が形成された従来の主軸受では、シリンダブロック内のオイルギャラリーから主軸受の潤滑油溝に供給された潤滑油が半割軸受の周方向端部まで流れることができるので、潤滑油に付随する異物は、主軸受の軸線方向溝とジャーナル部とによって形成される隙間を通して軸受外部に排出されることができる。しかしこの場合、異物とともに多量の潤滑油も軸受外部に排出されるため、潤滑油溝が形成された一方の半割軸受と対となる他方の半割軸受の内周面は油の供給が不十分となり、クランク軸のジャーナル部と直接接触し、損傷しやすい。 In a conventional main bearing in which an axial groove is formed at a joint portion of a pair of half bearings, lubricating oil supplied to a lubricating oil groove of the main bearing from an oil gallery in a cylinder block is applied to a circumferential end of the half bearing. As a result, foreign matter accompanying the lubricating oil can be discharged to the outside of the bearing through a gap formed by the axial groove of the main bearing and the journal portion. However, in this case, since a large amount of lubricating oil is discharged to the outside of the bearing together with the foreign matter, supply of oil to the inner peripheral surface of the other half bearing that is paired with the one half bearing in which the lubricating oil groove is formed is not performed. Sufficient, it comes into direct contact with the journal of the crankshaft and is easily damaged.

したがって本発明の目的は、内燃機関のクランク軸用主軸受であって、潤滑油に含まれる異物の排出機能を有しつつ、摺動面への油の供給に優れた主軸受を提供することである。本発明の他の目的は、そのような主軸受およびジャーナル部から構成される軸受装置を提供することである。 Accordingly, an object of the present invention is to provide a main bearing for a crankshaft of an internal combustion engine, which has a function of discharging foreign substances contained in lubricating oil and is excellent in supplying oil to a sliding surface. It is. Another object of the present invention is to provide a bearing device comprising such a main bearing and a journal portion.

上記目的を達成するために、本発明の第一の観点によれば、内燃機関のクランク軸のジャーナル部を回転自在に支持するための主軸受であって、ジャーナル部が、円筒胴部と、円筒胴部を貫通して延びる潤滑油路と、円筒胴部の外周面上に形成された潤滑油路の少なくとも１つの入口開口とを有している、主軸受において、
主軸受は第１および第２の半割軸受を有し、第１および第２の半割軸受は、第１の半割軸受のそれぞれの周方向端面を第２の半割軸受のそれぞれの周方向端面と突き合わせることによって円筒形状に組み合わされ、
第１および第２の半割軸受は、互いに組み合わされたとき、それぞれの突合せ部分の内周面側に、主軸受の軸線方向全長に亘って延びる軸線方向溝を共に形成するように構成され、
第１の半割軸受は、その内周面に周方向に延びる油溝を有し、この油溝の、クランク軸の回転方向前方側の周方向端部が、第１の半割軸受の内周面上に位置し、または第１の半割軸受の、クランク軸の回転方向前方側の周方向端面で開口し、
第２の半割軸受は、その内周面に周方向に延びる部分溝を有し、この部分溝の、クランク軸の回転方向後方側の周方向端部が、軸線方向溝から第２の半割軸受の周方向中央部側へ向かって円周角度１°以上離間して内周面上に位置し、また部分溝の、クランク軸の回転方向前方側の周方向端部が、第２の半割軸受の、クランク軸の回転方向後方側の周方向端面から第２の半割軸受の周方向中央部側へ向かって円周角度５°〜４５°の範囲内の内周面上に位置し、
油溝の、クランク軸の回転方向前方側の周方向端部と、部分溝の、クランク軸の回転方向後方側の周方向端部とはしたがって第１の周方向距離だけ離間しており、
油溝の軸線方向幅の中央、および部分溝の軸線方向幅の中央が、ジャーナル部の入口開口の中心と整合するように配置され、
第１の周方向距離Ｌ１が、ジャーナル部の入口開口の周方向長さＬ２より小さく、それにより前記油溝は、部分溝と、ジャーナル部の潤滑油路を介して流体連通するようになっている
主軸受が提供される。 In order to achieve the above object, according to a first aspect of the present invention, a main bearing for rotatably supporting a journal portion of a crankshaft of an internal combustion engine, wherein the journal portion has a cylindrical body portion, A main bearing having a lubricating oil passage extending through the cylindrical body and at least one inlet opening of the lubricating oil passage formed on the outer peripheral surface of the cylindrical body;
The main bearing has first and second half bearings, and the first and second half bearings each have a circumferential end face of the first half bearing which is in contact with a respective circumferential end surface of the second half bearing. Combined into a cylindrical shape by abutting the end face
When the first and second half bearings are combined with each other, the first and second half bearings are configured so as to form an axial groove extending along the entire axial length of the main bearing on the inner peripheral surface side of each butted portion,
The first half bearing has an oil groove extending in the circumferential direction on an inner peripheral surface thereof, and a circumferential end of the oil groove on the front side in the rotation direction of the crankshaft is formed in the first half bearing in the first half bearing. An opening at a circumferential end surface of the first half bearing, which is located on the circumferential surface or on the front side in the rotation direction of the crankshaft,
The second half bearing has, on its inner peripheral surface, a partial groove extending in the circumferential direction, and a circumferential end portion of the partial groove on the rear side in the rotation direction of the crankshaft is separated from the axial groove by the second half. The circumferential end of the partial groove is located on the inner peripheral surface at a circumferential angle of 1 ° or more toward the center in the circumferential direction of the split bearing. The half bearing is located on an inner circumferential surface within a range of a circumferential angle of 5 ° to 45 ° from a circumferential end face on the rear side in the rotation direction of the crankshaft toward a center part in a circumferential direction of the second half bearing. And
The circumferential end of the oil groove on the front side in the rotation direction of the crankshaft and the circumferential end of the partial groove on the rear side in the rotation direction of the crankshaft are therefore separated by a first circumferential distance,
The center of the axial width of the oil groove and the center of the axial width of the partial groove are arranged so as to be aligned with the center of the inlet opening of the journal portion,
The first circumferential distance L1 is smaller than the circumferential length L2 of the inlet opening of the journal portion, so that the oil groove is in fluid communication with the partial groove via the lubricating oil passage of the journal portion. Main bearings are provided.

本発明の一実施形態では、第１の周方向距離Ｌ１とジャーナル部の入口開口の周方向長さＬ２とが以下の関係式：
Ｌ２−Ｌ１≧０．５ｍｍ
を満たしていてもよい。 In one embodiment of the present invention, the first circumferential distance L1 and the circumferential length L2 of the inlet opening of the journal portion are represented by the following relational expression:
L2-L1 ≧ 0.5mm
May be satisfied.

本発明の他の実施形態では、第１の周方向距離Ｌ１とジャーナル部の入口開口の周方向長さＬ２とが以下の関係式：
Ｌ１≧Ｌ２×０．３
を満たしていてもよい。
より好ましくは、第１の周方向距離Ｌ１とジャーナル部の入口開口の周方向長さＬ２とが以下の関係式：
Ｌ１≧Ｌ２×０．６
を満たしていてもよい。 In another embodiment of the present invention, the first circumferential distance L1 and the circumferential length L2 of the inlet opening of the journal portion are represented by the following relational expression:
L1 ≧ L2 × 0.3
May be satisfied.
More preferably, the first circumferential distance L1 and the circumferential length L2 of the inlet opening of the journal portion are represented by the following relational expression:
L1 ≧ L2 × 0.6
May be satisfied.

本発明の他の実施形態では、油溝の軸線方向幅Ｗ１と部分溝の軸線方向幅Ｗ２とが以下の関係式：
Ｗ１≦Ｗ２
を満たしていてもよい。 In another embodiment of the present invention, the axial width W1 of the oil groove and the axial width W2 of the partial groove are represented by the following relational expression:
W1 ≦ W2
May be satisfied.

本発明の他の実施形態では、部分溝の軸線方向幅Ｗ２と、第２の半割軸受の軸線方向長さ（軸受幅）Ｌ３とが以下の関係式：
Ｗ２≧Ｌ３×０．５
を満たしていてもよい。 In another embodiment of the present invention, the axial width W2 of the partial groove and the axial length (bearing width) L3 of the second half bearing are represented by the following relational expressions:
W2 ≧ L3 × 0.5
May be satisfied.

本発明の他の実施形態では、第２の半割軸受の内周面からの部分溝の最大深さが０．０１〜０．１ｍｍであってもよい。 In another embodiment of the present invention, the maximum depth of the partial groove from the inner peripheral surface of the second half bearing may be 0.01 to 0.1 mm.

本発明のさらに他の実施形態では、主軸受の内周面からの軸線方向溝の最大深さが０．１〜１ｍｍであってもよい。
より好ましくは、主軸受の内周面からの軸線方向溝の最大深さが０．１〜０．５ｍｍであってもよい。 In still another embodiment of the present invention, the maximum depth of the axial groove from the inner peripheral surface of the main bearing may be 0.1 to 1 mm.
More preferably, the maximum depth of the axial groove from the inner peripheral surface of the main bearing may be 0.1 to 0.5 mm.

本発明の他の実施形態では、主軸受の内周面上における軸線方向溝の周方向幅が０．２〜２ｍｍであってもよい。 In another embodiment of the present invention, the circumferential width of the axial groove on the inner circumferential surface of the main bearing may be 0.2 to 2 mm.

本発明の他の実施形態では、第１および第２の半割軸受のそれぞれが、周方向両端面（前方側の周方向端面および後方側の周方向端面）に隣接して内周面側に形成されたクラッシュリリーフを有していてもよい。 In another embodiment of the present invention, each of the first and second half bearings is located on the inner peripheral surface side adjacent to both circumferential end surfaces (a front circumferential end surface and a rear circumferential end surface). It may have a formed crush relief.

本発明の他の実施形態では、ジャーナル部の円筒胴部の外周面上における入口開口の面積が、ジャーナル部内の潤滑油路の断面積より大きく、したがって入口開口と潤滑油路の間には断面積が徐々に変化する流路遷移部分が形成されていてもよい。
好ましくは、ジャーナル部の円筒胴部の外周面からの流路遷移部分の深さが１〜２ｍｍであってもよい。 In another embodiment of the present invention, the area of the inlet opening on the outer peripheral surface of the cylindrical body of the journal portion is larger than the cross-sectional area of the lubricating oil passage in the journal portion, and therefore, there is a break between the inlet opening and the lubricating oil passage. A flow path transition portion whose area gradually changes may be formed.
Preferably, the depth of the flow path transition portion from the outer peripheral surface of the cylindrical body of the journal portion may be 1 to 2 mm.

また本発明の第二の観点によれば、上述した第一の観点によるクランク軸用主軸受と、この主軸受によって支持されるジャーナル部とから構成される軸受装置が提供される。 According to a second aspect of the present invention, there is provided a bearing device including the crankshaft main bearing according to the first aspect described above, and a journal supported by the main bearing.

本発明によれば、主軸受の壁に形成された貫通口を通して油溝内に供給された潤滑油に付随する異物は、油溝と軸線方向溝が直接流体連通することにより、またはジャーナル部の入口開口が、主軸受の内周面の第１の周方向距離に相当する部分の上を通過する際に先ず油溝と軸線方向溝がジャーナル部の潤滑油路を介して流体連通することにより、主軸受の軸線方向溝から適切に排出されることができる。さらに、その後油溝と部分溝がジャーナル部の潤滑油路を介して流体連通することにより、異物を付随しない潤滑油が部分溝に流れ、第２の半割軸受の内周面に供給されることができる。 According to the present invention, foreign substances accompanying the lubricating oil supplied into the oil groove through the through hole formed in the wall of the main bearing are formed by direct fluid communication between the oil groove and the axial groove, or in the journal portion. When the inlet opening passes over a portion corresponding to a first circumferential distance of the inner peripheral surface of the main bearing, first, the oil groove and the axial groove are in fluid communication via the lubricating oil passage of the journal portion. , Can be properly discharged from the axial groove of the main bearing. Further, since the oil groove and the partial groove are in fluid communication with each other via the lubricating oil passage of the journal portion, the lubricating oil with no foreign matter flows into the partial groove and is supplied to the inner peripheral surface of the second half bearing. be able to.

本発明の他の目的、特徴および利点は、添付図面に関する以下の本発明の実施例の記載から明らかになるであろう。 Other objects, features and advantages of the present invention will become apparent from the following description of embodiments of the present invention with reference to the accompanying drawings.

内燃機関のクランク軸を、ジャーナル部およびクランクピンでそれぞれ截断した模式図である。It is the schematic diagram which cut | disconnected the crankshaft of the internal combustion engine by the journal part and the crankpin, respectively. 本発明の実施例１によるクランク軸用主軸受、およびクランク軸の正面図である。1 is a front view of a crankshaft main bearing and a crankshaft according to a first embodiment of the present invention. 図２に示す主軸受の上側の第１の半割軸受を軸受内周面側から見た平面図である。FIG. 3 is a plan view of a first half bearing on an upper side of the main bearing shown in FIG. 2 when viewed from a bearing inner peripheral surface side. 図２に示す主軸受の下側の第２の半割軸受を軸受内周面側から見た平面図である。FIG. 3 is a plan view of a second half bearing on the lower side of the main bearing shown in FIG. 2 as viewed from the inner peripheral surface side of the bearing. 図２示す主軸受の第２の半割軸受の正面図である。FIG. 3 is a front view of a second half bearing of the main bearing shown in FIG. 2. 図２に示す主軸受の第１および第２の半割軸受の接合部、ならびにクランク軸の軸線方向から見た拡大断面図である。FIG. 3 is an enlarged cross-sectional view of a joint portion of first and second half bearings of the main bearing shown in FIG. 2 and a crankshaft viewed from an axial direction. 図２に示す主軸受の接合部を軸受内周面側から見た図である。FIG. 3 is a view of a joint portion of a main bearing shown in FIG. 2 as viewed from a bearing inner peripheral surface side. 図２に示す主軸受の接合部の拡大正面図である。FIG. 3 is an enlarged front view of a joint of the main bearing shown in FIG. 2. 図２に示す第２の半割軸受の周方向端部付近を軸線方向から見た拡大断面図である。FIG. 3 is an enlarged cross-sectional view of the vicinity of an end in a circumferential direction of a second half bearing shown in FIG. 2 as viewed from an axial direction. 図２に示す主軸受の接合部およびクランク軸の他の例の軸線方向から見た拡大断面図である。FIG. 3 is an enlarged cross-sectional view of another example of a joint portion of a main bearing and a crankshaft shown in FIG. 2 when viewed from an axial direction. 図２に示す主軸受の機能を説明するための、主軸受の接合部を軸線方向から見た拡大断面図である。FIG. 3 is an enlarged cross-sectional view of a joint portion of the main bearing viewed from an axial direction, for describing a function of the main bearing illustrated in FIG. 2. 本発明の実施例２によるクランク軸用主軸受、およびクランク軸の正面図である。FIG. 5 is a front view of a crankshaft main bearing and a crankshaft according to a second embodiment of the present invention. 図１２に示す主軸受の上側の第１の半割軸受を軸受内周面側から見た平面図である。FIG. 13 is a plan view of a first half bearing on the upper side of the main bearing shown in FIG. 12 when viewed from a bearing inner peripheral surface side. 図１２に示す主軸受の下側の第２の半割軸受を軸受内周面側から見た平面図である。FIG. 13 is a plan view of a second half bearing on the lower side of the main bearing shown in FIG. 12 as viewed from the bearing inner peripheral surface side. 図１２に示す主軸受の接合部をクランク軸の軸線方向から見た拡大断面図である。FIG. 13 is an enlarged cross-sectional view of a joint portion of the main bearing shown in FIG. 12 when viewed from an axial direction of a crankshaft. 図１２に示す主軸受の接合部を軸受内周面側から見た図である。FIG. 13 is a view of a joint portion of the main bearing shown in FIG. 12 as viewed from the bearing inner peripheral surface side. 図１２に示す主軸受の機能を説明するための、主軸受の接合部を軸線方向から見た拡大断面図である。FIG. 13 is an enlarged cross-sectional view illustrating a joint portion of the main bearing viewed from an axial direction, for describing a function of the main bearing illustrated in FIG. 12. 図１２に示す主軸受の機能を説明するための、主軸受の接合部を軸線方向から見た拡大断面図である。FIG. 13 is an enlarged cross-sectional view illustrating a joint portion of the main bearing viewed from an axial direction, for describing a function of the main bearing illustrated in FIG. 12. 図１２に示す主軸受の機能を説明するための、主軸受の接合部を軸受内周面側から見た図である。FIG. 13 is a diagram for explaining a function of the main bearing shown in FIG. 12, in which a joint portion of the main bearing is viewed from the inner peripheral surface side of the bearing. 図１２に示す主軸受の機能を説明するための、主軸受の接合部を軸線方向から見た拡大断面図である。FIG. 13 is an enlarged cross-sectional view illustrating a joint portion of the main bearing viewed from an axial direction, for describing a function of the main bearing illustrated in FIG. 12. クラッシュリリーフを設けた場合の図２に示す主軸受の接合部の軸線方向から見た拡大断面図である。FIG. 3 is an enlarged cross-sectional view of a joint portion of a main bearing shown in FIG. 2 when a crush relief is provided, as viewed from an axial direction.

以下、添付図面を参照しながら本発明の実施例について説明する。 Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings.

図１は、内燃機関のクランク軸を、ジャーナル部およびクランクピンでそれぞれ截断した模式図であり、ジャーナル部１０、クランクピン１２およびコンロッド１４を示す。これら三部材の紙面奥行き方向での位置関係として、ジャーナル部１０が紙面の奥側に、クランクピン１２が手前側にあり、このクランクピン１２は、他端にピストンを担持するコンロッド１４の大端部ハウジング１６で包囲されている。 FIG. 1 is a schematic diagram in which a crankshaft of an internal combustion engine is cut by a journal portion and a crankpin, respectively, and shows a journal portion 10, a crankpin 12, and a connecting rod 14. As for the positional relationship of these three members in the depth direction of the paper, the journal part 10 is on the back side of the paper, and the crank pin 12 is on the front side, and the crank pin 12 is a large end of a connecting rod 14 carrying a piston at the other end. It is surrounded by the housing 16.

ジャーナル部１０は、一対の半割軸受１７、１８から構成される主軸受１９を介して、内燃機関のシリンダブロック下部（図示せず）に支持されている。図面で上側に位置する第１の半割軸受１７に、周方向の全長に亘って周方向に延びる油溝１７Ｇが内周面に形成されている。ジャーナル部１０はその直径方向に貫通孔（潤滑油路）１０ａを有し、ジャーナル部１０が矢印Ｘ方向に回転すると、貫通孔１０ａの両端の入口開口が交互に油溝１７Ｇに連通する。図面で下側に位置する第２の半割軸受１８に、部分的に周方向に延びる部分溝１８Ｇが内周面に形成されている。 The journal portion 10 is supported at a lower portion (not shown) of a cylinder block of the internal combustion engine via a main bearing 19 including a pair of half bearings 17 and 18. In the first half bearing 17 located on the upper side in the drawing, an oil groove 17G extending in the circumferential direction over the entire length in the circumferential direction is formed on the inner circumferential surface. The journal portion 10 has a through hole (lubricating oil passage) 10a in its diameter direction. When the journal portion 10 rotates in the direction of the arrow X, the inlet openings at both ends of the through hole 10a alternately communicate with the oil groove 17G. In the second half bearing 18 located on the lower side in the drawing, a partial groove 18G partially extending in the circumferential direction is formed on the inner peripheral surface.

ジャーナル部１０、図示されないクランクアーム、およびクランクピン１２を貫通して、貫通孔１０ａに連通する内部潤滑油路２０がクランク軸内部に形成されている。 An internal lubricating oil passage 20 penetrating through the journal portion 10, the crank arm (not shown), and the crank pin 12 and communicating with the through hole 10a is formed inside the crankshaft.

クランクピン１２は、一対の半割軸受２２Ａ、２２Ｂから構成されるコンロッド軸受２２を介して、コンロッド１４の（コンロッド側大端部ハウジング１６Ａとキャップ側大端部ハウジング１６Ｂから構成される）大端部ハウジング１６に保持されている。 The crank pin 12 is connected to a large end of the connecting rod 14 (comprising a connecting rod side large end housing 16A and a cap side large end housing 16B) via a connecting rod bearing 22 formed of a pair of half bearings 22A and 22B. It is held by the unit housing 16.

図２〜図９に、主軸受１９を構成する一対の半割軸受１７、１８の詳細を示す。図２の紙面上側の第１の半割軸受１７は、ジャーナル部１０の回転方向Ｘの前方側に配置される前方側周方向端面１７Ａ、および後方側に配置される後方側周方向端面１７Ｂを有する。下側の第２の半割軸受１８は、ジャーナル部１０の回転方向Ｘの前方側に配置される前方側周方向端面１８Ｂ、および後方側に配置される後方側周方向端面１８Ａを有する。第１の半割軸受１７の前方側周方向端面１７Ａは第２の半割軸受１８の後方側周方向端面１８Ａと突き合わされ、また第２の半割軸受１８の前方側周方向端面１８Ｂは第１の半割軸受１７の後方側周方向端面１７Ｂと突き合わされ、それによって円筒形状の主軸受１９を構成している。
ところで、内燃機関のクランク軸は、運転時には一方向に回転する。このため当業者であれば、クランク軸の回転方向を考慮し、第１の半割軸受１７の周方向両端面のうち、どちらが「ジャーナル部１０の回転方向Ｘの前方側に配置される前方側周方向端面１７Ａ」であり、どちらが「ジャーナル部１０の回転方向Ｘの後方側に配置される後方側周方向端面１７Ｂ」であるか認定することができよう。同じく、当業者であれば第２の半割軸受１８の「ジャーナル部１０の回転方向Ｘの前方側に配置される前方側周方向端面１８Ｂ」および「ジャーナル部１０の回転方向Ｘの後方側に配置される後方側周方向端面１８Ａ」も認定することができよう。また当業者であれば、本発明の開示にしたがって本発明の主軸受１９を設計、製造し、これを一方向に回転するクランク軸を支承する軸受装置に適切に組み付けることが可能である。 2 to 9 show details of a pair of half bearings 17 and 18 constituting the main bearing 19. The first half bearing 17 on the upper side of the drawing of FIG. 2 has a front circumferential end face 17A arranged on the front side in the rotation direction X of the journal section 10 and a rear circumferential end face 17B arranged on the rear side. Have. The lower second half bearing 18 has a front circumferential end face 18B arranged on the front side in the rotation direction X of the journal portion 10 and a rear circumferential end face 18A arranged on the rear side. The front circumferential end face 17A of the first half bearing 17 abuts against the rear circumferential end face 18A of the second half bearing 18, and the front circumferential end face 18B of the second half bearing 18 is The half bearing 17 is abutted against the rear circumferential end face 17B of the half bearing 17, thereby forming a cylindrical main bearing 19.
Incidentally, the crankshaft of the internal combustion engine rotates in one direction during operation. For this reason, a person skilled in the art considers the rotation direction of the crankshaft, and considers which one of the two circumferential end faces of the first half bearing 17 is “the front side disposed on the front side in the rotation direction X of the journal portion 10”. The circumferential end face 17A "may be identified, and which is the" rear circumferential end face 17B arranged rearward in the rotation direction X of the journal portion 10 ". Similarly, those skilled in the art will understand that the second half bearing 18 has a “front side circumferential end face 18B disposed on the front side in the rotation direction X of the journal portion 10” and a “rear side in the rotation direction X of the journal portion 10”. The rear circumferential end face 18A to be arranged "may also be recognized. Further, those skilled in the art can design and manufacture the main bearing 19 of the present invention according to the disclosure of the present invention, and appropriately assemble the main bearing 19 into a bearing device that supports a crankshaft that rotates in one direction.

第１の半割軸受１７の前方側周方向端面１７Ａおよび後方側周方向端面１７Ｂは、その内周面側に、軸線方向の全長に亘って面取りの態様で形成された傾斜面１７Ｃ、１７Ｄをそれぞれ有し、また第２の半割軸受１８の前方側周方向端面１８Ｂおよび後方側周方向端面１８Ａは、その内周面側に、軸線方向の全長に亘って同様に形成された傾斜面１８Ｄ、１８Ｃをそれぞれ有し、それによって半割軸受１７、１８の接合部（または突合せ部）には軸線方向溝２４Ａ、２４Ｂが形成される。 The front peripheral end face 17A and the rear peripheral end face 17B of the first half bearing 17 have inclined surfaces 17C, 17D formed in a chamfered form over the entire length in the axial direction on the inner peripheral surface side. The front-side circumferential end face 18B and the rear-side circumferential end face 18A of the second half bearing 18 each have an inclined surface 18D formed on the inner circumferential surface thereof over the entire length in the axial direction. , 18C, respectively, whereby axial grooves 24A, 24B are formed at the joints (or abutments) of the half bearings 17, 18 respectively.

図２および図３から理解されるように、第１の半割軸受１７の内周面１７Ｓに形成された油溝１７Ｇは、第１の半割軸受１７の内周面の周方向の全長に亘って延びており、第１の半割軸受１７の周方向両端面１７Ａ、１７Ｂに開口している。なお、本実施例では、油溝１７Ｇは、周方向の全長に亘って、第１の半割軸受１７の内周面１７Ｓからの溝深さが一定になされている。しかし、これに限定されないで、油溝１７Ｇの溝深さは、周方向で変化していてもよい。また油溝１７Ｇの最大溝深さは、例えば乗用車用の小型の内燃機関の場合、一般的に０．５〜２．５ｍｍ程度であるが、本発明はこれに限定されない。また本実施例では、油溝１７Ｇは、主軸受の軸線方向断面内において矩形断面形状を有するが、他の断面形状であってもよい。 As understood from FIGS. 2 and 3, the oil groove 17 G formed on the inner peripheral surface 17 S of the first half bearing 17 extends over the entire length of the inner peripheral surface of the first half bearing 17 in the circumferential direction. The first half bearing 17 is open at both circumferential end faces 17A and 17B. In the present embodiment, the oil groove 17G has a constant groove depth from the inner peripheral surface 17S of the first half bearing 17 over the entire length in the circumferential direction. However, without being limited to this, the groove depth of the oil groove 17G may be changed in the circumferential direction. The maximum groove depth of the oil groove 17G is generally about 0.5 to 2.5 mm in a small internal combustion engine for a passenger car, for example, but the present invention is not limited to this. In the present embodiment, the oil groove 17G has a rectangular cross-sectional shape in the axial cross section of the main bearing, but may have another cross-sectional shape.

図３から理解されるように、油溝１７Ｇは第１の半割軸受１７の軸線方向長さ（軸受幅）の中央に配置される。油溝１７Ｇの底部には第１の半割軸受１７を径方向に貫通する貫通口（図示せず）が形成され、潤滑油は、シリンダブロックの壁内のオイルギャラリーから、この貫通口を通して油溝１７Ｇ内に供給される。潤滑油の一部はその後、ジャーナル部１０の矢印Ｘ方向の回転にしたがって油溝１７Ｇ内を回転方向前方へ流れ、潤滑油の他の一部は油溝１７Ｇ内を回転方向と反対方向に流れる。第１の半割軸受１７はまた、油溝１７Ｇの幅Ｗ１の中央がジャーナル部１０の潤滑油路１０ａの入口開口２６の中心と整合するように配置されているので（図７は、図６の回転位置にある入口開口２６を破線で示す）、油溝１７Ｇ内に供給された潤滑油は、入口開口２６を通してコンロッド軸受２２へとさらに流れることができる。ジャーナル部１０の潤滑油路１０ａの入口開口２６の寸法は、内燃機関の仕様により異なるが、例えば乗用車用の小型の内燃機関の場合、入口開口２６の径寸法はφ５〜８ｍｍ程度である。 As understood from FIG. 3, the oil groove 17 G is arranged at the center of the axial length (bearing width) of the first half bearing 17. A through hole (not shown) is formed at the bottom of the oil groove 17G to penetrate the first half bearing 17 in the radial direction. It is supplied into the groove 17G. A portion of the lubricating oil then flows forward in the rotation direction in the oil groove 17G according to the rotation of the journal portion 10 in the direction of the arrow X, and another portion of the lubrication oil flows in the oil groove 17G in the direction opposite to the rotation direction. . The first half bearing 17 is also arranged such that the center of the width W1 of the oil groove 17G is aligned with the center of the inlet opening 26 of the lubricating oil passage 10a of the journal portion 10 (FIG. The lubricating oil supplied into the oil groove 17 G can further flow to the connecting rod bearing 22 through the inlet opening 26. The size of the inlet opening 26 of the lubricating oil passage 10a of the journal portion 10 varies depending on the specifications of the internal combustion engine. For example, in the case of a small internal combustion engine for a passenger car, the diameter of the inlet opening 26 is about 5 to 8 mm.

図４および図５から理解されるように、第２の半割軸受１８の内周面１８Ｓには周方向に延びる部分溝１８Ｇが形成されており、部分溝１８Ｇの周方向両端部１８ＧＦ、１８ＧＲが第２の半割軸受１８の内周面１８Ｓに位置している。より詳細には、図５に示すように、部分溝１８Ｇの、クランク軸の回転方向Ｘの後方側の周方向端部１８ＧＲは、軸線方向溝２４Ａから第２の半割軸受１８の周方向中央部Ｃ側へ向かって円周角度θ１で１°以上離間した内周面１８Ｓ上に位置し、またクランク軸の回転方向Ｘの前方側の周方向端部１８ＧＦは、第２の半割軸受１８の後方側周方向端面１８Ａから第２の半割軸受１８の周方向中央部Ｃ側へ向かって円周角度θ２で５°〜４５°の範囲内の内周面１８Ｓ上に位置する。したがって図７に示すように、軸線方向溝２４Ａと、部分溝１８Ｇの、クランク軸の回転方向Ｘの後方側の周方向端部１８ＧＲとの間には分離内周面１８Ｓ’が形成される。第２の半割軸受１８はまた、部分溝１８Ｇの幅Ｗ２の中央がジャーナル部１０の潤滑油路１０ａの入口開口２６の中心と整合するように配置されている。
なお、本実施例では、第１の半割軸受１７の油溝１７Ｇの軸線方向における幅Ｗ１（油溝１７Ｇの、クランク軸の回転方向Ｘの前方側の周方向端部での幅）と、第２の半割軸受１８の部分溝１８Ｇの軸線方向における幅Ｗ２（部分溝１８Ｇの、クランク軸の回転方向Ｘの後方側の周方向端部１８ＧＲでの幅）は、同じになされている。
また、図９に示すように、部分溝１８Ｇの、第２の半割軸受１８の内周面１８Ｓからの最大深さＤ２は、０．０１〜０．１ｍｍであることが好ましい。本実施例では、部分溝１８Ｇの、第２の半割軸受１８の内周面１８Ｓからの深さは、部分溝１８Ｇの周方向長さの中央部付近で最大であり、周方向両端部側へ向かって小さくなっている。なお、部分溝１８Ｇもまた、矩形断面形状を有している。 As understood from FIGS. 4 and 5, a partial groove 18G extending in the circumferential direction is formed on the inner peripheral surface 18S of the second half bearing 18, and both circumferential ends 18GF, 18GR of the partial groove 18G are formed. Are located on the inner peripheral surface 18 S of the second half bearing 18. More specifically, as shown in FIG. 5, the circumferential end 18GR of the partial groove 18G on the rear side in the rotation direction X of the crankshaft extends from the axial groove 24A to the circumferential center of the second half bearing 18. A circumferential end 18GF located on the inner circumferential surface 18S separated by 1 ° or more at a circumferential angle θ1 toward the portion C side, and a circumferential end portion 18GF on the front side in the rotation direction X of the crankshaft is connected to the second half bearing 18. Is located on the inner peripheral surface 18S within a range of 5 ° to 45 ° at a circumferential angle θ2 from the rear circumferential end face 18A toward the circumferential center portion C side of the second half bearing 18. Therefore, as shown in FIG. 7, a separation inner peripheral surface 18S 'is formed between the axial groove 24A and the circumferential end 18GR of the partial groove 18G on the rear side in the rotation direction X of the crankshaft. The second half bearing 18 is also arranged such that the center of the width W2 of the partial groove 18G is aligned with the center of the inlet opening 26 of the lubricating oil passage 10a of the journal portion 10.
In the present embodiment, the width W1 of the oil groove 17G of the first half bearing 17 in the axial direction (the width of the oil groove 17G at the circumferential end on the front side in the rotation direction X of the crankshaft) is set; The width W2 of the partial groove 18G of the second half bearing 18 in the axial direction (the width of the partial groove 18G at the circumferential end 18GR on the rear side in the crankshaft rotation direction X) is the same.
Also, as shown in FIG. 9, the maximum depth D2 of the partial groove 18G from the inner peripheral surface 18S of the second half bearing 18 is preferably 0.01 to 0.1 mm. In the present embodiment, the depth of the partial groove 18G from the inner peripheral surface 18S of the second half bearing 18 is maximum near the center of the circumferential length of the partial groove 18G, and on both ends in the circumferential direction. It is getting smaller towards. Note that the partial groove 18G also has a rectangular cross-sectional shape.

図６は、図２に示す主軸受１９の紙面右側の接合部を、クランク軸の軸線方向から見た拡大断面図を示す。
第１の半割軸受１７の油溝１７Ｇの、クランク軸の回転方向前方側の周方向端部と、第２の半割軸受１８の部分溝１８Ｇの、クランク軸の回転方向後方側の周方向端部１８ＧＲとは、第１の周方向距離Ｌ１だけ離間していることが理解されよう。この第１の周方向距離Ｌ１は、ジャーナル部１０の潤滑油路２０入口開口２６の周方向長さＬ２より小さくなされており、したがって油溝１７Ｇと軸線方向溝２４Ａと部分溝１８Ａとは、潤滑油路１０ａを介して流体連通可能である。 FIG. 6 is an enlarged cross-sectional view of the joint on the right side of the paper of the main bearing 19 shown in FIG. 2 as viewed from the axial direction of the crankshaft.
A circumferential end of the oil groove 17G of the first half bearing 17 on the front side in the rotation direction of the crankshaft, and a circumferential direction of the partial groove 18G of the second half bearing 18 on the rear side in the rotation direction of the crankshaft. It will be appreciated that the end 18GR is spaced a first circumferential distance L1. The first circumferential distance L1 is smaller than the circumferential length L2 of the lubricating oil passage 20 inlet opening 26 of the journal portion 10, so that the oil groove 17G, the axial groove 24A, and the partial groove 18A are lubricated. Fluid communication is possible via the oil passage 10a.

入口開口２６は、図６では潤滑油路１０ａと同じ断面積を有するものとして記載している。しかし入口開口２６は、加工の結果として図１０に示すように潤滑油路１０ａより大きい断面積を有していてもよく、またジャーナル部１０の外周面上において円形または楕円形の開口形状を有していてもよい。入口開口２６の断面積が潤滑油路１０ａの断面積より大きい場合、入口開口２６と潤滑油路１０ａの間には断面積が油路方向に徐々に変化する流路遷移部分２９が、ジャーナル部１０の外周面から深さ１〜２ｍｍまで形成される。いずれの場合も、入口開口２６はジャーナル部１０の外周面上における周方向長さ（直線距離）Ｌ２を有するものと定義される。 In FIG. 6, the inlet opening 26 is described as having the same cross-sectional area as the lubricating oil passage 10a. However, as shown in FIG. 10, the inlet opening 26 may have a larger cross-sectional area than the lubricating oil passage 10a as a result of machining, and may have a circular or elliptical opening shape on the outer peripheral surface of the journal portion 10. It may be. When the cross-sectional area of the inlet opening 26 is larger than the cross-sectional area of the lubricating oil passage 10a, between the inlet opening 26 and the lubricating oil passage 10a, a flow path transition portion 29 whose cross-sectional area gradually changes in the oil passage direction is formed. 10 from the outer peripheral surface to a depth of 1 to 2 mm. In any case, the inlet opening 26 is defined as having a circumferential length (linear distance) L2 on the outer peripheral surface of the journal portion 10.

油溝１７Ｇに供給される潤滑油に異物２８が混入していると、異物２８は油溝１７Ｇ内をクランク軸の回転方向Ｘの前方側に流れる潤滑油に付随して油溝１７Ｇのクランク軸の回転方向Ｘの前方側の周方向端部へ移動し、油溝１７Ｇと連通する軸線方向溝２４Ａへ流れて軸受外部へ排出される（図７参照）。従来のクランク軸用主軸受では、多量の潤滑油が軸受外部へ排出されるため、第２の半割軸受の内周面への潤滑油の供給量が不足し、したがって第２の半割軸受の内周面がクランク軸のジャーナル部１０と直接接触し、これは損傷を引き起こす原因となっていた。また、第２の半割軸受の内周面への潤滑油の供給量を増やすために、第２の半割軸受の、クランク軸の回転方向Ｘの後方側の周方向端面に開口するように部分溝を内周面に形成して、この部分溝と油溝１７Ｇとを直接連通させた場合、油溝１７Ｇ内の多量の異物が潤滑油とともに部分溝を通して第２の半割軸受の内周面に侵入するようになり、これは第２の半割軸受の内周面に損傷を引き起こす原因となっていた。
しかし本発明の実施例によれば、油溝１７Ｇと部分溝１８Ｇの間に分離内周部１８Ｓ’が存在するので、油溝１７Ｇ内の異物２８が部分溝１８Ｇに流れ込むことが妨げられる。さらに、油溝１７Ｇと部分溝１８Ｇとが第１の周方向距離Ｌ１だけ離間し、且つ第１の周方向距離Ｌ１が入口開口２６の周方向長さＬ２よりも小さいので、ジャーナル部１０の回転に伴って入口開口２６が分離内周面１８Ｓ’上に位置したとき、図１１に示すように油溝１７Ｇが潤滑油路１０ａを介して部分溝１８Ｇと連通し、それにより油溝１７内の潤滑油が部分溝１８Ｇへ流入することができる。 If the foreign matter 28 is mixed with the lubricating oil supplied to the oil groove 17G, the foreign matter 28 accompanies the lubricating oil flowing in the oil groove 17G forward in the rotation direction X of the crankshaft. To the circumferential end on the front side in the rotation direction X, flows into the axial groove 24A communicating with the oil groove 17G, and is discharged outside the bearing (see FIG. 7). In the conventional main bearing for a crankshaft, a large amount of lubricating oil is discharged to the outside of the bearing, so that the supply amount of the lubricating oil to the inner peripheral surface of the second half bearing is insufficient. Has come into direct contact with the journal portion 10 of the crankshaft, which has caused damage. Further, in order to increase the supply amount of the lubricating oil to the inner peripheral surface of the second half bearing, the second half bearing is opened at the circumferential end face on the rear side in the rotation direction X of the crankshaft. When a partial groove is formed on the inner peripheral surface and the partial groove and the oil groove 17G are directly communicated with each other, a large amount of foreign matter in the oil groove 17G passes through the partial groove together with the lubricating oil and the inner peripheral surface of the second half bearing. The bearing surface, which causes damage to the inner peripheral surface of the second half bearing.
However, according to the embodiment of the present invention, since the separation inner peripheral portion 18S 'exists between the oil groove 17G and the partial groove 18G, foreign matter 28 in the oil groove 17G is prevented from flowing into the partial groove 18G. Further, since the oil groove 17G and the partial groove 18G are separated by the first circumferential distance L1 and the first circumferential distance L1 is smaller than the circumferential length L2 of the inlet opening 26, the rotation of the journal 10 is When the inlet opening 26 is located on the separation inner peripheral surface 18S ′, the oil groove 17G communicates with the partial groove 18G via the lubricating oil passage 10a as shown in FIG. Lubricating oil can flow into the partial groove 18G.

より詳細には、油溝１７Ｇが潤滑油路１０ａを介して部分溝１８Ｇと連通したとき、（１）ジャーナル部１０の回転による遠心力Ｆ１、（２）油溝１７Ｇ内と潤滑油路１０ａ内の潤滑油の圧力勾配による流れ力Ｆ２、および（３）潤滑油路１０ａ内と部分溝１８Ｇ内の潤滑油の圧力勾配による流れ力Ｆ３が、入口開口２６付近の潤滑油に同時に作用し、油溝１７Ｇから潤滑油路１０ａ内に進入した潤滑油を部分溝１８Ｇ内へ移動させるのに十分な潤滑油の流れが瞬間的に形成される。 More specifically, when the oil groove 17G communicates with the partial groove 18G via the lubricating oil passage 10a, (1) the centrifugal force F1 due to the rotation of the journal portion 10, (2) the oil groove 17G and the lubricating oil passage 10a. Flow force F2 due to the pressure gradient of the lubricating oil, and (3) the flow force F3 due to the pressure gradient of the lubricating oil in the lubricating oil passage 10a and the partial groove 18G simultaneously act on the lubricating oil near the inlet opening 26, A flow of lubricating oil sufficient to move the lubricating oil that has entered the lubricating oil passage 10a from the groove 17G into the partial groove 18G is instantaneously formed.

本発明によれば、油溝１７Ｇの、クランク軸１０の回転方向Ｘの前方側の周方向端部と、部分溝１８Ｇの、クランク軸１０の回転方向Ｘの後方側の周方向端部１８ＧＲとの間の第１の周方向距離Ｌ１が入口開口２６の周方向長さＬ２よりも小さいことが要求される。その理由は、Ｌ１≧Ｌ２の場合、入口開口２６が部分溝１８Ｇと連通を開始したときに入口開口２６は油溝１７Ｇと既に連通しておらず、それゆえ図１１に示す油溝１７Ｇからの流れ力Ｆ２が生じないので、潤滑油路１０ａに進入した潤滑油を部分溝１８Ｇに押し流すことができなくなるからである。 According to the present invention, the circumferential end of the oil groove 17G on the front side in the rotation direction X of the crankshaft 10 and the circumferential end 18GR of the partial groove 18G on the rear side in the rotation direction X of the crankshaft 10 are formed. Is required to be smaller than the circumferential length L2 of the inlet opening 26. The reason is that when L1 ≧ L2, when the inlet opening 26 starts to communicate with the partial groove 18G, the inlet opening 26 is not already in communication with the oil groove 17G, and therefore, the oil opening 17G shown in FIG. This is because the flow force F2 is not generated, so that the lubricating oil that has entered the lubricating oil passage 10a cannot be flushed into the partial groove 18G.

潤滑油路１０ａに進入した潤滑油を部分溝１８Ｇに押し出すのに十分な潤滑油の流れのために、油溝１７Ｇと部分溝１８Ｇの間の第１の周方向距離Ｌ１と、入口開口２６の周方向長さＬ２とが、Ｌ２−Ｌ１≧０．５ｍｍの関係を満たすことが好ましい。また油溝１７Ｇが部分溝１８Ｇと流体連通している際に過剰に潤滑油が流出することを防止するため、第１の周方向距離Ｌ１と入口開口２６の周方向長さＬ２とが、Ｌ１≧Ｌ２×０．３の関係を満たしていることが好ましく、またＬ１≧Ｌ２×０．６の関係を満たしていることがより好ましい。これは、第１の周方向距離Ｌ１が短すぎると、油溝１７Ｇと部分溝１８Ｇとが流体連通する時間が長くなり、油溝１７Ｇの周方向端部から部分溝１８Ｇに流れ込む油量が増加して油溝１７Ｇ内の潤滑油の圧力が低下し、したがってコンロッド軸受２２へ送られる油量が減少するためである。 The first circumferential distance L1 between the oil groove 17G and the partial groove 18G and the opening of the inlet opening 26 are set so that the lubricating oil that has entered the lubricating oil passage 10a flows enough to push the lubricating oil into the partial groove 18G. It is preferable that the circumferential length L2 satisfies the relationship of L2−L1 ≧ 0.5 mm. In order to prevent the lubricating oil from flowing out excessively when the oil groove 17G is in fluid communication with the partial groove 18G, the first circumferential distance L1 and the circumferential length L2 of the inlet opening 26 are equal to L1. It is preferable that the relationship of ≧ L2 × 0.3 is satisfied, and it is more preferable that the relationship of L1 ≧ L2 × 0.6 is satisfied. This is because if the first circumferential distance L1 is too short, the time for fluid communication between the oil groove 17G and the partial groove 18G increases, and the amount of oil flowing from the circumferential end of the oil groove 17G into the partial groove 18G increases. As a result, the pressure of the lubricating oil in the oil groove 17G decreases, and the amount of oil sent to the connecting rod bearing 22 decreases.

第２の半割軸受１８の内周面１８Ｓにおける、部分溝１８Ｇの、クランク軸の回転方向Ｘの後方側の周方向端部１８ＧＲは、軸線方向溝２４Ａから第２の半割軸受１８の周方向中央部Ｃ側へ向かって円周角度θ１で１°以上離間した内周面上に位置するので、油溝１７Ｇの前方側の周方向端部から軸線方向溝２４Ａに流れ込んだ異物が、この軸線方向溝２４Ａを越えて部分溝１８Ｇへ流入することが防がれる。また部分溝１８Ｇの、クランク軸の回転方向Ｘの前方側の周方向端部１８ＧＦは、第２の半割軸受１８の後方側周方向端面１８Ａから第２の半割軸受１８の周方向中央部Ｃ側へ向かって円周角度θ２で５°〜４５°の範囲内の内周面上に位置する。部分溝１８Ｇの、クランク軸の回転方向Ｘの前方側の周方向端部１８ＧＦの位置が第２の半割軸受１８の後方側周方向端面１８Ａから第２の半割軸受１８の周方向中央部Ｃ側へ向かって円周角度θ２で５°未満であると、第２の半割軸受１８の周方向中央部Ｃ付近へ潤滑油が送られ難く、またこの円周角度θ２が４５°を超えると、第２の半割軸受１８の内周面１８Ｓの面積が少なくなるため好ましくない。また内周面１８Ｓに沿った部分溝１８Ｇの周方向長さは、円周角度で１０°〜３０°に相当する長さであることが好ましい。 A circumferential end 18GR of the partial groove 18G on the inner peripheral surface 18S of the second half bearing 18 on the rear side in the crankshaft rotation direction X is formed from the axial groove 24A to the periphery of the second half bearing 18. Foreign matter that has flowed into the axial groove 24A from the front circumferential end of the oil groove 17G is located on the inner circumferential surface separated by 1 ° or more at the circumferential angle θ1 toward the direction center portion C side. The flow into the partial groove 18G beyond the axial groove 24A is prevented. The circumferential end 18GF on the front side of the partial groove 18G on the front side in the rotation direction X of the crankshaft extends from the rear circumferential end face 18A of the second half bearing 18 to the center in the circumferential direction of the second half bearing 18. It is located on the inner peripheral surface within the range of 5 ° to 45 ° at the circumferential angle θ2 toward the C side. The position of the circumferential end 18GF on the front side in the crankshaft rotation direction X of the partial groove 18G is from the rear circumferential end face 18A of the second half bearing 18 to the center in the circumferential direction of the second half bearing 18. If the circumferential angle θ2 is less than 5 ° toward the C side, it is difficult for the lubricating oil to be sent to the vicinity of the circumferential central portion C of the second half bearing 18, and the circumferential angle θ2 exceeds 45 °. This is not preferable because the area of the inner peripheral surface 18S of the second half bearing 18 is reduced. The circumferential length of the partial groove 18G along the inner peripheral surface 18S is preferably a length corresponding to a circumferential angle of 10 ° to 30 °.

主軸受１９の内周面上における軸線方向溝２４Ａの周方向長さ（直線距離）Ｌ４は０．２〜２ｍｍとすることができ、また主軸受１９の内周面からの軸線方向溝２４Ａの最大深さＤ１は０．１〜１ｍｍ、好ましくは０．１〜０．５ｍｍとすることができる（図８参照）。軸線方向溝２４Ａの周方向長さＬ４および深さＤ１は、潤滑油に混入する異物のサイズ（一般には最大０．１ｍｍ程度）に鑑みて、異物を排出可能な最小寸法としてもよい。 The circumferential length (linear distance) L4 of the axial groove 24A on the inner peripheral surface of the main bearing 19 can be 0.2 to 2 mm, and the axial groove 24A from the inner peripheral surface of the main bearing 19 can be formed. The maximum depth D1 can be 0.1 to 1 mm, preferably 0.1 to 0.5 mm (see FIG. 8). The circumferential length L4 and the depth D1 of the axial groove 24A may be set to the minimum size capable of discharging the foreign matter in consideration of the size of the foreign matter mixed into the lubricating oil (generally, about 0.1 mm at the maximum).

上述したように入口開口２６の断面積が潤滑油路１０ａの断面積より大きく、したがって流路遷移部分２９が少なくとも入口開口２６の周方向両側に形成されている場合、油溝１７Ｇと部分溝１８Ｇが流体連通したときに油溝１７Ｇ内の潤滑油が流路遷移部分２９の傾斜面によって誘導され潤滑油路１０ａ内へ流れ易くなり、さらに部分溝１８Ｇへ流れ易くなるので、潤滑油を部分溝１８Ｇに向けて押し流す周方向の流れＦ３（図１１）を強めることができる。 As described above, when the cross-sectional area of the inlet opening 26 is larger than the cross-sectional area of the lubricating oil passage 10a, and therefore the flow path transition portion 29 is formed at least on both circumferential sides of the inlet opening 26, the oil groove 17G and the partial groove 18G are formed. When the fluid is in fluid communication, the lubricating oil in the oil groove 17G is guided by the inclined surface of the flow path transition portion 29 and easily flows into the lubricating oil passage 10a, and further flows into the partial groove 18G. The circumferential flow F3 (FIG. 11) to be pushed toward 18G can be strengthened.

本実施例によるクランク軸用主軸受１９は、第１および第２の半割軸受１７、１８の軸受壁厚が周方向に亘って一定に形成されているが、これら半割軸受１７、１８の軸受壁厚は、半割軸受１７、１８の周方向中央部Ｃで最大で、周方向両端部側へ向かって小さくなるように形成することもできる。またこれら半割軸受１７、１８の内周面１７Ｓ、１８Ｓは、複数の円弧面により構成されていてもよい。 In the crankshaft main bearing 19 according to the present embodiment, the bearing wall thickness of the first and second half bearings 17 and 18 is formed constant in the circumferential direction. The bearing wall thickness can be formed so as to be maximum at the central portion C in the circumferential direction of the half bearings 17 and 18 and to decrease toward both ends in the circumferential direction. Also, the inner peripheral surfaces 17S, 18S of these half bearings 17, 18 may be constituted by a plurality of arc surfaces.

本発明によるクランク軸用主軸受１９は、第１および第２の半割軸受１７、１８の接合部に隣接する軸受内周面にクラッシュリリーフ４２、４４を有していてもよい。クラッシュリリーフは、図２１に示すように、各半割軸受１７、１８の周方向端部領域において壁部の厚さを回転中心と同心である本来の内周面４０（主要円弧）から半径方向に減じることによって形成される逃し空間４２、４４のことであり、これは、例えば一対の半割軸受１７、１８をクランク軸１０のジャーナル部１９に組み付けた時に生じ得る半割軸受の周方向端面の位置ずれや変形を吸収するために形成される。したがって、例えばクラッシュリリーフ４２が形成された領域Ｒでの軸受内周面１７Ｓの曲率中心位置は、その他の領域における軸受内周面（主要円弧）の曲率中心位置と異なる（ＳＡＥＪ５０６（項目３．２６および項目６．４）、ＤＩＮ１４９７、セクション３．２、ＪＩＳＤ３１０２参照）。なお、この場合であっても、第２の半割軸受１８の内周面１８Ｓ上に分離内周部１８Ｓ’が形成されることが理解されよう。一般に、乗用車用の小型の内燃機関用軸受の場合、半割軸受の周方向端面におけるクラッシュリリーフの深さ（本来の内周面から実際の内周面までの距離）は０．０１〜０．０５ｍｍ程度である。 The crankshaft main bearing 19 according to the present invention may have crush reliefs 42, 44 on the bearing inner peripheral surface adjacent to the joint between the first and second half bearings 17, 18. As shown in FIG. 21, the crush relief changes the thickness of the wall in the circumferential end regions of the half bearings 17 and 18 from the original inner peripheral surface 40 (main arc) concentric with the rotation center in the radial direction. The clearance spaces 42 and 44 formed by reducing the diameter of the crankshaft 10 are, for example, circumferential end faces of the half bearings that can be generated when the pair of half bearings 17 and 18 are assembled to the journal portion 19 of the crankshaft 10. It is formed in order to absorb the displacement and deformation of the. Therefore, for example, the center of curvature of the bearing inner peripheral surface 17S in the region R where the crush relief 42 is formed is different from the center of curvature of the bearing inner peripheral surface (main arc) in other regions (SAE J506 (item 3.)). 26 and item 6.4), DIN 1497, section 3.2, JIS D3102). It should be understood that, even in this case, the separated inner peripheral portion 18S 'is formed on the inner peripheral surface 18S of the second half bearing 18. Generally, in the case of a small internal-combustion engine bearing for a passenger car, the depth of the crush relief (distance from the original inner peripheral surface to the actual inner peripheral surface) at the circumferential end surface of the half bearing is 0.01 to 0.5 mm. It is about 05 mm.

図１２は、本発明の実施例２によるクランク軸用主軸受１９を示す。実施例２によるクランク軸用主軸受１９の、実施例１と共通する構成については説明を省略する。
この主軸受１９は、一対の半割軸受１７、１８から構成される。図１３〜図１４に、主軸受１９を構成する一対の半割軸受１７、１８の詳細を示す。
図１３から理解されるように、第１の半割軸受１７の内周面１７Ｓに形成された油溝１７Ｇは、第１の半割軸受１７の周方向に延び、且つ油溝１７Ｇの周方向両端部１７ＧＦ、１７ＧＲは、第１の半割軸受１７の内周面１７Ｓ上に位置する。なお、油溝１７Ｇは、油溝１７Ｇの、クランク軸１０の回転方向Ｘの前方側の周方向端部１７ＧＦが第１の半割軸受１７の内周面１７Ｓに位置し、且つ油溝１７Ｇの、クランク軸１０の回転方向Ｘの後方側の周方向端部１７ＧＲが第１の半割軸受１７の後方側周方向端面１７Ｂに開口するように構成されてもよい。 FIG. 12 shows a main bearing 19 for a crankshaft according to a second embodiment of the present invention. The description of the configuration of the crankshaft main bearing 19 according to the second embodiment that is common to the first embodiment will be omitted.
The main bearing 19 includes a pair of half bearings 17 and 18. 13 and 14 show details of a pair of half bearings 17 and 18 constituting the main bearing 19.
As understood from FIG. 13, the oil groove 17 G formed on the inner peripheral surface 17 S of the first half bearing 17 extends in the circumferential direction of the first half bearing 17 and extends in the circumferential direction of the oil groove 17 G. Both ends 17GF and 17GR are located on the inner peripheral surface 17S of the first half bearing 17. The oil groove 17 G has a circumferential end 17 GF on the front side in the rotation direction X of the crankshaft 10 of the oil groove 17 G located on the inner circumferential surface 17 S of the first half bearing 17. The circumferential end portion 17GR on the rear side in the rotation direction X of the crankshaft 10 may be configured to open to the rear circumferential end surface 17B of the first half bearing 17.

図１４から理解されるように、第２の半割軸受１８の内周面１８Ｓに形成された部分溝１８Ｇは、部分溝１８Ｇの周方向両端部１８ＧＦ、１８ＧＲが第２の半割軸受１８の内周面１８Ｓ上に位置するように形成されている。なお、本実施例では、第２の半割軸受１８の部分溝１８Ｇの軸線方向幅Ｗ２は、第１の半割軸受１７の油溝１７Ｇの軸線方向幅Ｗ１よりも大きくなされている。
ここで、第２の半割軸受１８の部分溝１８Ｇの軸線方向幅Ｗ２と、第２の半割軸受１８の軸線方向長さ（軸受幅）Ｌ３とが以下の関係式：
Ｗ２≧Ｌ３×０．５
を満たしていることが好ましい。また、部分溝１８Ｇの軸線方向幅Ｗ２は、第２の半割軸受１８の軸線方向長さＬ３よりも２ｍｍ小さくし、部分溝１８Ｇの軸線方向の両側に内周面１８Ｓが各１ｍｍ残るようにする必要がある。 As can be understood from FIG. 14, the partial groove 18G formed on the inner peripheral surface 18S of the second half bearing 18 is configured such that both circumferential end portions 18GF and 18GR of the partial groove 18G are the same as those of the second half bearing 18. It is formed so as to be located on the inner peripheral surface 18S. In this embodiment, the axial width W2 of the partial groove 18G of the second half bearing 18 is larger than the axial width W1 of the oil groove 17G of the first half bearing 17.
Here, the axial width W2 of the partial groove 18G of the second half bearing 18 and the axial length (bearing width) L3 of the second half bearing 18 are represented by the following relational expressions:
W2 ≧ L3 × 0.5
Is preferably satisfied. Further, the axial width W2 of the partial groove 18G is set to be smaller than the axial length L3 of the second half bearing 18 by 2 mm, and the inner peripheral surfaces 18S are left by 1 mm on both axial sides of the partial groove 18G. There is a need to.

第１の半割軸受１７の油溝１７Ｇの、クランク軸の回転方向Ｘの前方側の周方向端部１７ＧＦと、第２の半割軸受１８の部分溝１８Ｇの、クランク軸の回転方向Ｘの後方側の周方向端部１８ＧＲとは、第１の周方向距離Ｌ１だけ離間しており、またそれらの間には、第２の半割軸受１８側の分離内周面１８Ｓ’に加え、第１の半割軸受１７側に分離内周面１７Ｓ’が形成されている（図１５および図１６参照）。第１の周方向距離Ｌ１は、ジャーナル部１０の潤滑油路１０ａの入口開口２６の周方向長さＬ２より小さく、したがって油溝１７Ｇは、潤滑油路１０ａを介して軸線方向溝２４Ａおよび部分溝１８Ｇと流体連通可能である。 The circumferential end 17GF of the oil groove 17G of the first half bearing 17 on the front side in the crankshaft rotation direction X and the partial groove 18G of the second half bearing 18 in the rotation direction X of the crankshaft. The rear circumferential end portion 18GR is separated from the rear circumferential end portion 18GR by a first circumferential distance L1. In addition to the separation inner circumferential surface 18S 'on the second half bearing 18 side, A separated inner peripheral surface 17S 'is formed on the half bearing 17 side (see FIGS. 15 and 16). The first circumferential distance L1 is smaller than the circumferential length L2 of the inlet opening 26 of the lubricating oil passage 10a of the journal portion 10, so that the oil groove 17G is formed via the lubricating oil passage 10a with the axial groove 24A and the partial groove. It can be in fluid communication with 18G.

（作用）
油溝１７Ｇに供給される潤滑油に異物２８が混入していると、異物２８は油溝１７Ｇ内をクランク軸の回転方向Ｘの前方側に流れる潤滑油に付随して、油溝１７Ｇの、クランク軸の回転方向Ｘの前方側の周方向端部１７ＧＦへ移動するが、油溝１７Ｇと軸線方向溝２４Ａとが直接流体連通していないと、異物２８が油溝１７Ｇの周方向端部１７ＧＦ付近に滞留したり、潤滑油路１０ａに進入しやすい（図１７）。しかし本実施例によれば、油溝１７Ｇと部分溝１８Ｇの間の第１の周方向距離Ｌ１が入口開口２６の周方向長さＬ２よりも小さく形成されているので、ジャーナル部１０の回転に伴って入口開口２６が油溝１７Ｇの周方向端部１７ＧＦ上を通過した後、入口開口２６が第１の半割軸受１７側の分離内周面１７Ｓ’上に位置し、したがって油溝１７Ｇが潤滑油路１０ａを介して先ず軸線方向溝２４Ａのみと流体連通したとき、潤滑油路１０ａに進入した異物２８は軸線方向溝２４Ａへ排出される（図１８）。 (Action)
If the foreign matter 28 is mixed in the lubricating oil supplied to the oil groove 17G, the foreign matter 28 is attached to the lubricating oil flowing forward in the rotation direction X of the crankshaft in the oil groove 17G, When the oil groove 17G and the axial groove 24A are not in direct fluid communication with each other, the foreign matter 28 may move to the circumferential end 17GF of the oil groove 17G. It easily stays in the vicinity or enters the lubricating oil passage 10a (FIG. 17). However, according to the present embodiment, the first circumferential distance L1 between the oil groove 17G and the partial groove 18G is formed to be smaller than the circumferential length L2 of the inlet opening 26. Accordingly, after the inlet opening 26 has passed over the circumferential end 17GF of the oil groove 17G, the inlet opening 26 is located on the separation inner peripheral surface 17S 'on the first half bearing 17 side, and therefore the oil groove 17G is When the fluid is first communicated only with the axial groove 24A via the lubricating oil passage 10a, the foreign matter 28 having entered the lubricating oil passage 10a is discharged to the axial groove 24A (FIG. 18).

より詳細には、油溝１７Ｇが潤滑油路１０ａを介して先ず軸線方向溝２４Ａのみと流体連通したとき、図１８に示すように、（１）ジャーナル部１０の回転による遠心力Ｆ１、（２）油溝１７Ｇ内と潤滑油路１０ａ内の潤滑油の圧力勾配による流れ力Ｆ２、および（３）潤滑油路１０ａ内と軸線方向溝２４Ａ内の潤滑油の圧力勾配による流れ力Ｆ３が、入口開口２６付近にある潤滑油路１０ａ内部の異物２８および潤滑油に同時に作用し、潤滑油路１０ａ内に進入した異物２８を軸線方向溝２４Ａへ移動させるのに十分な潤滑油の流れが瞬間的に形成される。またこの瞬間、軸線方向溝２４Ａ内には主軸受１９の軸線方向への流れも形成され、異物２８の軸受外への排出を助ける（図１９参照）。 More specifically, when the oil groove 17G is first in fluid communication only with the axial groove 24A via the lubricating oil passage 10a, as shown in FIG. 18, (1) the centrifugal force F1, (2) The flow force F2 due to the pressure gradient of the lubricating oil in the oil groove 17G and the lubricating oil passage 10a, and the flow force F3 due to the pressure gradient of the lubricating oil in the lubricating oil passage 10a and the axial groove 24A are increased at the inlet. The lubricating oil acts simultaneously on the foreign matter 28 and the lubricating oil inside the lubricating oil passage 10a near the opening 26, and the flow of the lubricating oil sufficient to move the foreign matter 28 having entered the lubricating oil passage 10a to the axial groove 24A is instantaneous. Formed. At this moment, a flow in the axial direction of the main bearing 19 is also formed in the axial groove 24 A, which helps discharge the foreign matter 28 out of the bearing (see FIG. 19).

その後、ジャーナル部１０の回転により、油溝１７ａが潤滑油路１０ａを介して部分溝１８Ｇとも連通すると、図２０に示すように、（１）ジャーナル部１０の回転による遠心力Ｆ１、（２）油溝１７ａ内と潤滑油路１０ａ内の潤滑油の圧力勾配による流れ力Ｆ２、および（３）潤滑油路１０ａ内と部分溝１８Ｇ内の潤滑油の圧力勾配による流れ力Ｆ３が、入口開口２６付近にある潤滑油路１０ａ内部の異物２８を含まない潤滑油に同時に作用し、潤滑油路１０ａ内に進入した潤滑油を部分溝１８Ｇ内へ移動させるのに十分な潤滑油の流れが瞬間的に形成される。 Thereafter, when the oil groove 17a communicates with the partial groove 18G via the lubricating oil passage 10a by the rotation of the journal portion 10, as shown in FIG. 20, (1) the centrifugal force F1 due to the rotation of the journal portion 10, (2) The flow force F2 due to the pressure gradient of the lubricating oil in the oil groove 17a and the lubricating oil passage 10a, and (3) the flow force F3 due to the pressure gradient of the lubricating oil in the lubricating oil passage 10a and the partial groove 18G are increased by the inlet opening 26. The lubricating oil that does not contain the foreign matter 28 in the nearby lubricating oil passage 10a simultaneously acts on the lubricating oil, and the flow of the lubricating oil sufficient to move the lubricating oil that has entered the lubricating oil passage 10a into the partial groove 18G is instantaneously generated. Formed.

なお、実施例１および２において、下側の第２の半割軸受１８は、クランク軸の回転方向Ｘの後方側の所定の内周面１８Ｓ上に部分溝１８Ｇを有しているが、回転方向Ｘの前方側の内周面１８Ｓ上に周方向中央部Ｃに関して対称な部分溝をさらに有していてもよい。このような対称形状を採用することにより、シリンダブロック下部の軸受キャップへの第２の半割軸受１８の誤った組み付けが防止される。 In the first and second embodiments, the lower second half bearing 18 has a partial groove 18G on a predetermined inner peripheral surface 18S on the rear side in the rotation direction X of the crankshaft. A partial groove symmetrical with respect to the circumferential central portion C may be further provided on the inner circumferential surface 18S on the front side in the direction X. By employing such a symmetrical shape, erroneous assembly of the second half bearing 18 on the bearing cap under the cylinder block is prevented.

１０ジャーナル部１０
１０ａ貫通孔（潤滑油路）
１２クランクピン１２
１４コンロッド１４
１６大端部ハウジング１６
１６Ａコンロッド側大端部ハウジング
１６Ｂキャップ側大端部ハウジング
１７第１の半割軸受
１７Ｇ油溝
１７ＧＦ（油溝の）回転方向前方側の周方向端部
１７Ａ（第１の半割軸受の）前方側周方向端面
１７Ｂ（第１の半割軸受の）後方側周方向端面
１７Ｃ、１７Ｄ傾斜面
１７Ｓ内周面
１７Ｓ’ 分離内周部
１８第２の半割軸受
１８Ａ（第２の半割軸受の）後方側周方向端面
１８Ｂ（第２の半割軸受の）前方側周方向端面
１８Ｄ、１８Ｃ傾斜面
１８Ｇ部分溝
１８ＧＦ（部分溝の）回転方向前方側の周方向端部
１８ＦＲ（部分溝の）回転方向後方側の周方向端部
１８Ｓ内周面
１８Ｓ’ 分離内周部
１９主軸受
２０内部潤滑油路
２２コンロッド軸受
２４Ａ、２４Ｂ軸線方向溝
２６入口開口
２８異物
２９流路遷移部分
４２、４４クラッシュリリーフまたは逃し空間 10 Journal part 10
10a Through hole (lubricating oil passage)
12 crank pin 12
14 Connecting rod 14
16 Large end housing 16
16A Connecting rod-side large-end housing 16B Cap-side large-end housing 17 First half bearing 17G Oil groove 17GF Circumferential end 17A (in the oil groove) rotation direction front side 17A Forward (of first half bearing) Side circumferential end face 17B Rear circumferential end face (of first half bearing) 17C, 17D Inclined surface 17S Inner circumferential surface 17S 'Separated inner circumferential portion 18 Second half bearing 18A (of second half bearing) ) Rear circumferential end face 18B Front circumferential end face (of the second half bearing) 18D, 18C Inclined face 18G Partial groove 18GF Rotational front circumferential end 18FR (of partial groove) 18FR (of partial groove) Circumferential end on the rear side in the rotation direction 18S Inner peripheral surface 18S 'Separated inner peripheral portion 19 Main bearing 20 Internal lubricating oil passage 22 Connecting rod bearing 24A, 24B Axial groove 26 Inlet opening 28 Foreign matter 29 Flow passage transition portion 4 , 44 crash relief or missed space

Claims

A main bearing for rotatably supporting a journal portion of a crankshaft of an internal combustion engine, wherein the journal portion has a cylindrical body, a lubricating oil passage extending through the cylindrical body, and the cylindrical body. A main bearing having at least one inlet opening of the lubricating oil passage formed on the outer peripheral surface of the main bearing,
The main bearing has first and second half bearings, and the first and second half bearings each have a circumferential end face of the first half bearing that is a second half bearing. Combined into a cylindrical shape by abutting against each circumferential end face of
When the first and second half bearings are combined with each other, an axial groove extending over the entire axial length of the main bearing is formed together on the inner peripheral surface side of each butted portion. And
The first half bearing has an oil groove extending in the circumferential direction on an inner peripheral surface thereof, and a circumferential end of the oil groove on a front side in the rotation direction of the crankshaft is provided on the inner peripheral surface. Located at the circumferential end face of the first half bearing on the rotation direction front side of the crankshaft,
The second half bearing has a partial groove extending in the circumferential direction on an inner peripheral surface thereof, and a circumferential end of the partial groove on the rear side in the rotation direction of the crankshaft is formed from the axial groove. A circumferential direction of the second half bearing that is located on the inner circumferential surface at a circumferential angle of 1 ° or more toward the center in the circumferential direction of the second half bearing. An end portion has a circumferential angle of 5 ° to 45 ° from a circumferential end face of the second half bearing on the rear side in the rotational direction of the crankshaft toward a circumferential center portion of the second half bearing. Located on the inner peripheral surface within the range of
The circumferential end of the oil groove on the front side in the rotation direction of the crankshaft and the circumferential end of the partial groove on the rear side in the rotation direction of the crankshaft are therefore separated by a first circumferential distance. And
The center of the axial width of the oil groove, and the center of the axial width of the partial groove are arranged so as to match the center of the inlet opening of the journal portion,
The first circumferential distance is smaller than the circumferential length of the inlet opening of the journal portion, so that the oil groove is in fluid communication with the partial groove via the lubricating oil passage of the journal portion. Main bearing.

The main bearing according to claim 1, wherein the first circumferential distance L1 and the circumferential length L2 of the inlet opening of the journal portion satisfy a relational expression: L2-L1 ≥ 0.5 mm.

The main bearing according to claim 1, wherein the first circumferential distance L1 and the circumferential length L2 of the inlet opening of the journal portion satisfy a relational expression: L1 ≧ L2 × 0.3.

The main bearing according to claim 3, wherein the first circumferential distance L1 and the circumferential length L2 of the inlet opening of the journal portion satisfy a relational expression: L1 ≥ L2 x 0.6.

5. The main bearing according to claim 1, wherein the axial width W1 of the oil groove and the axial width W2 of the partial groove satisfy a relational expression: W1 ≦ W2. 6.

The axial width W2 of the partial groove and the axial length L3 of the second half bearing satisfy a relational expression: W2 ≧ L3 × 0.5. Main bearing described in the item.

The main bearing according to any one of claims 1 to 6, wherein a maximum depth of the partial groove from an inner peripheral surface of the second half bearing is 0.01 to 0.1 mm.

The main bearing according to any one of claims 1 to 7, wherein a maximum depth of the axial groove from an inner peripheral surface of the main bearing is 0.1 to 1 mm.

The main bearing according to claim 8, wherein the maximum depth of the axial groove from the inner peripheral surface of the main bearing is 0.1 to 0.5 mm.

The main bearing according to any one of claims 1 to 9, wherein a circumferential width of the axial groove on the inner circumferential surface of the main bearing is 0.2 to 2 mm.

The said 1st and 2nd half bearing each has two crush reliefs formed in the inner peripheral surface side adjacent to the both ends in the circumferential direction, The crush relief in any one of Claims 1-10. Main bearing.

The area of the inlet opening on the outer peripheral surface of the cylindrical body of the journal portion is larger than the cross-sectional area of the lubricating oil passage in the journal portion. The main bearing according to any one of claims 1 to 11, wherein a gradually changing flow path transition portion is formed.

The main bearing according to claim 12, wherein a depth of the flow path transition portion from an outer peripheral surface of the cylindrical body of the journal portion is 1 to 2 mm.

A bearing device comprising: the main bearing according to any one of claims 1 to 13; and the journal portion supported by the main bearing.