JP2013019517A - Sliding bearing - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enhance durability by reducing local contact strees in a metal sliding surface in a thrust direction.SOLUTION: A thrust metal part 12c in a crank arm 5c side of the respective thrust metal parts 12b, 12c of a bisected sliding bearing 12 is formed into a flange-shape of a usual flat surface, a crowning surface 12f is formed to in the metal sliding surface in the thrust metal part 12b in a large diameter part 5 side. The crowning surface 12f into a curved surface shape convexed toward the large diameter part 5a, it becomes possible to reduce the contact stress between the large diameter part 5a and the thrust metal part 12b when flexion or inclination is generated in the large diameter part 5a by the crowning surface 12f, thereby seizure and fatigue breakage can be prevented by absorbing biased contact of the thrust metal part 12b periphery and the large diameter part 5a.

Description

  The present invention relates to a sliding bearing in which a thrust bearing portion is formed by a metal sliding surface.

  Conventionally, a plain bearing that forms a bearing with a metal sliding surface has been used in various industrial fields. For example, in a vehicle such as an automobile, many journals provided on a rotating shaft such as a crankshaft or a camshaft of an engine are supported on an engine body such as a cylinder block or a cylinder head by a sliding bearing.

  In such a sliding bearing, for example, in the case of a sliding bearing that supports a crankshaft, the axial load due to the explosion pressure in the cylinder during engine operation acts as a bending load, so a local contact occurs on the metal sliding surface. This can easily cause damage to the bearing or seizure.

  For this reason, Patent Document 1 discloses a relief having curved crowned surfaces that are cut at a constant depth from the inner surface of the bearing end surface at both ends of the bearing inner surface of the flat bearing and are smoothly connected to the inner surface from the cut portion. By forming the part, even if the rotating shaft such as the crankshaft is bent and deformed by the axial load such as the explosion pressure and tilted in the bearing, the inner surface of the bearing is aligned with the deformation of the rotating shaft by the relief portion having the crowning surface Further, there is disclosed a technique for reducing the bearing pressure by preventing the occurrence of local contact at the end of the bearing as a bearing surface and distributing the bearing load due to the axial load evenly on the bearing surface.

JP-A-9-177758

  However, as a plain bearing for supporting a rotating shaft such as a crankshaft, not only a plain bearing as disclosed in Patent Document 1, but also a radial metal and a thrust metal are integrally provided, and a thrust is received while receiving a radial load. There are sliding bearings that restrict the movement of directions. In such a sliding bearing, local contact of the metal sliding surface due to the deflection of the rotating shaft becomes noticeable in the thrust direction, and seizure / fatigue damage due to an increase in local contact stress is likely to occur.

  This invention is made | formed in view of the said situation, and it aims at providing the sliding bearing which can reduce the local contact stress in the metal sliding surface of a thrust direction, and can improve durability.

  A sliding bearing according to the present invention includes a radial bearing portion that rotatably supports a rotating shaft, and a thrust bearing portion that is provided at an end of the radial bearing portion and restricts movement of the rotating shaft in the axial direction. A crowning surface in which at least the outer peripheral side is formed in a curved shape is provided on the metal sliding surface of the thrust bearing portion.

  According to the present invention, the local contact stress can be reduced by the crowning surface provided on the metal sliding surface of the thrust bearing portion, and the durability can be improved.

Schematic configuration diagram showing a power train of a vehicle to which the slide bearing of the present invention is applied Section A enlarged sectional view of FIG. B-B 'line sectional view of FIG. Perspective view of half sliding bearing Enlarged view of main parts of thrust bearing Explanatory drawing showing the wear state of thrust metal

Embodiments of the present invention will be described below with reference to the drawings.
In FIG. 1, reference numeral 1 denotes a power train of a vehicle, which is connected to an engine 2 that is a drive source, a torque converter 3 that is connected to the output side of the engine 2, and an output side of the torque converter 3. And an automatic transmission 4. The torque converter 3 includes a pump impeller 3b fixed to the converter case 3a, a turbine runner 3c facing the pump impeller 3b, and a stator 3d.

  A converter case 3 a is connected to the output shaft 2 a of the engine 2, while a turbine runner 3 c is connected to the transmission input shaft 4 a of the automatic transmission 4. When the pump impeller 3b rotates in response to the output from the output shaft 2a of the engine 2, the stored hydraulic fluid (ATF) circulates, and the power is amplified and transmitted to the turbine runner 3c via this hydraulic fluid, This power is transmitted to the transmission input shaft 4a of the automatic transmission 4.

  The automatic transmission 4 is a continuously variable transmission in FIG. In the automatic transmission 4, a primary pulley 4b is mounted on a transmission input shaft 4a, a secondary pulley 4d is mounted on a transmission output shaft 4c, and winding transmission means such as a belt or a chain is provided on both pulleys 4b and 4d. 4e is wound, and a desired gear ratio is set by relatively changing the groove width (pulley width) of both pulleys 4b and 4d by hydraulic control or the like.

  The output shaft 2 a of the engine 2 is integrally formed at the rear end of the crankshaft 5 as a rotation shaft and protrudes rearward from the rear end of the engine 2. As shown in FIG. 2, the crankshaft 5 has a large-diameter portion 5 a as a flange portion formed on the inner shaft side of the output shaft 2 a, and a tip side from the large-diameter portion 5 a is provided in a cylinder block of the engine 2. The crank chamber 6 is disposed.

  The crankshaft 5 has crank journals 5b and crankpins (not shown) alternately formed on the inner shaft side of the large-diameter portion 5a via crank arms 5c as flange portions, so that the front portion of the engine 2 Extended in the direction. The crankshaft 5 disposed on the front side of the engine 2 and its peripheral structure are the same as those in the prior art, and a description thereof is omitted here.

  The large-diameter portion 5a of the crankshaft 5 is rotatably inserted into an oil seal retainer 7 fixed to the rear end outer wall of the engine 2 via an oil seal 8 while maintaining oil tightness. A crank journal 5b adjacent to the large-diameter portion 5a is bolted to the bearing housing 6b formed in the crank chamber 6 and formed at the lower end of a partition wall 6a separating each cylinder. The bearing cap 9 is formed in a ring-shaped bearing hole 10 and is slidably supported via a sliding bearing 11.

  As shown in FIG. 3, the bearing hole 10 is formed by butting bearing surfaces 10 a and 10 b having a semicircular cross section formed in the bearing housing 6 b and the bearing cap 9. On the other hand, the sliding bearing 11 is formed in an annular shape by abutting two half-sliding bearings 12 of the same shape mounted on the bearing surfaces 10a and 10b. In FIG. 3, a part of the thrust metal portion 12b is broken.

  The half-slide bearing 12 is formed by lining an alloy such as a copper alloy or an aluminum alloy on a back metal such as a steel plate, and as shown in FIG. 4, a thrust bearing portion mounted on the bearing surfaces 10a and 10b. As a radial metal portion 12a and thrust metal portions 12b and 12c as thrust bearing portions formed in a flange shape on both axial sides thereof. An oil groove 12d is formed along the circumferential direction at the center in the width direction of the inner peripheral surface of the radial metal portion 12a where the crank journal 5b is slidably contacted, and an oil hole 12e is formed in the middle. The partition wall 6a is formed with a lubricating oil passage 6c that communicates with the oil hole 12e and supplies lubricating oil to the oil groove 12d through the oil hole 12e.

  The radial metal portion 12a and the thrust metal portions 12b and 12c may be integrally formed in advance by bending, welding, or the like. Alternatively, the radial metal portion 12a and the thrust metal portions 12b and 12c are individually produced and attached at the time of mounting. It may be a thing to be made.

  The thrust metal portions 12b and 12c of the half sliding bearing 12 are mounted on stepped portions 10c and 10d formed on both sides of the bearing housing 6b and the bearing surfaces 10a and 10b of the bearing cap 9, respectively. FIG. 5 (and FIG. 2) shows a state in which the radial metal portion 12a of the half sliding bearing 12 is attached to the bearing surfaces 10a and 10b and the thrust metal portions 12b and 12c on both sides thereof are attached to the step portions 10c and 10d. In this manner, one thrust metal portion 12b is provided on the front end surface of the large diameter portion 5a, and the other thrust metal portion 12b is provided on the crank arm 5c.

  In the present embodiment, the thrust metal portion 12c on the crank arm 5c side is formed in a normal flat flange shape, and the metal sliding on the large diameter portion 5a side is placed on the thrust metal portion 12b on the large diameter portion 5a side. A crowning surface 12f is formed on the surface. In the present embodiment, as shown in FIG. 5, the crowning surface 12f is formed in a curved surface that is convex toward the large-diameter portion 5a, and a moment is applied to the large-diameter portion 5a by the crowning surface 12f. Even when the large-diameter portion 5a is bent or inclined, the contact stress between the large-diameter portion 5a and the thrust metal portion 12b can be reduced, and the peripheral portion of the thrust metal portion 12b and the large-diameter portion 5a. It is possible to prevent seizure and fatigue damage by absorbing the contact with each other.

  Note that the crowning surface 12f only needs to be provided at least on the outer peripheral side of the thrust metal portion 12c, and a crowning surface having a tapered or curved axial section may be formed on the outer peripheral side of the thrust metal portion 12c. .

  Hereinafter, the operation of the sliding bearing 12 accompanying the operation of the power train 1 in the present embodiment will be described.

  When the engine 2 is operated, the crankshaft 5 rotates, and the output is transmitted from the output shaft 2a to the pump impeller 3b via the converter case 3a of the torque converter 3, and the pump impeller 3b rotates. The pump impeller 3b rotates to cause a flow in the hydraulic oil, and the turbine runner 3c rotates due to the inertial force of the hydraulic oil flow. At this time, the stator 3d rectifies the hydraulic oil and reduces it to the pump impeller 3b, thereby generating a torque amplifying action. Then, a predetermined torque-amplified output is input to the transmission input shaft 4a of the automatic transmission 4, and the driving force shifted by the automatic transmission 4 is transmitted from the transmission output shaft 4c to the driving wheels. The vehicle travels.

  On the other hand, between the crank journal 5b of the crankshaft 5 and the sliding bearing 11 that supports the crank journal 5b, the lubricating oil is supplied from the lubricating oil passage 6c formed in the partition wall 6a. The lubricating oil supplied from the lubricating oil passage 6c passes through the oil hole 12e of each half sliding bearing 12 constituting the sliding bearing 11, and is discharged into the oil groove 12d formed on the inner periphery of the radial metal portion 12a. From this oil groove 12d, it flows between the radial metal part 12a and the crank journal 5b, and lubricates between them. The lubricating oil lubricated between the radial metal portion 12a and the crank journal 5b is between one thrust metal portion 12b formed on both sides of the radial metal portion 12a and the front end face of the large diameter portion 5a, and The space between the other thrust metal portion 12c and the crank arm 5c is lubricated and scattered in the crank chamber 6.

  Here, when the engine 2 is rotated and the gear of the automatic transmission 4 is engaged, the pump impeller 3b rotates at the same speed as the crankshaft 5 when the vehicle is stopped (so-called stalled state). become. On the other hand, since the vehicle is stopped, the transmission input shaft 4a does not rotate and the turbine runner 3c does not rotate, and the hydraulic oil flows out from the pump impeller 3b by centrifugal force along the rotation direction.

  At this time, since the rotation of the turbine runner 3c is stopped, the hydraulic oil generates frictional heat with a large number of turbine blades formed in the turbine runner 3c, and the hydraulic oil itself is generated by this frictional heat. In addition to thermal expansion, the components of the torque converter 3 also thermally expand. As a result, a thrust load that presses the crankshaft 5 in the distal direction acts on the output shaft 2a via the converter case 3a. Further, a thrust load that presses the crankshaft 5 in the rear end direction (transmission direction) acts from the front side of the engine 2 via a camshaft drive mechanism (not shown).

  Even if the transmission is a manual transmission, a thrust load that presses the crankshaft 5 in the distal direction is generated similarly. That is, when the friction clutch of the manual transmission is fastened, the pressing force from the friction clutch generates a force that presses the crankshaft 5 in the distal direction, and a similar thrust load is generated.

  In this way, when a thrust load from the front-rear direction or a moment due to the vertical movement of the piston acts on the crankshaft 5, the crankshaft 5 is deflected, and the side surface of the large-diameter portion 5a and the rear end of the half-slide bearing 12 The gap with the thrust metal part 12b on the side becomes non-uniform. At this time, in the conventional conventional half-sliding bearing, the thrust metal portion is formed in a flat flange shape, so that one-side contact occurs between the thrust metal portion 12b and the large-diameter portion 5a, and a local contact occurs. Contact stress increases and seizure / fatigue damage is likely to occur.

  On the other hand, in the half sliding bearing 12 according to the present embodiment, the crowning surface 12f is provided on the thrust metal portion 12c on the rear end side, so that even when the crankshaft is bent and deformed locally Contact stress can be reduced. FIG. 6 shows measurement data of the surface wear amount of the thrust metal portion 12b when the engine 2 is continuously operated under predetermined test conditions. The wear amount δ shown in FIGS. 6B and 6C on the metal surface in the radial direction L1 and the metal surface in the circumferential direction L2 shown in FIG. It can be seen that the amount of wear in the thrust metal is significantly reduced.

  Thus, by providing a crowning surface on the thrust metal portion 12b, it is possible to prevent damage such as metal wear and seizure, improve durability, and realize a thrust bearing with a low friction coefficient and low sliding loss. be able to. In addition, since it is possible to increase the surface pressure resistance of the thrust metal, it is possible to reduce the diameter of the thrust metal portion 12b and use a relatively inexpensive metal material, which can contribute to a reduction in product cost.

DESCRIPTION OF SYMBOLS 5 Crankshaft 5a Large diameter part 5b Crank journal 10 Bearing hole 10a, 10b Bearing surface 11 Sliding bearing 12 Half sliding bearing 12a Radial metal part 12b, 12c Thrust metal part 12f Crowning surface

Claims (2)

A radial bearing that rotatably supports the rotating shaft, and a thrust bearing that is provided at an end of the radial bearing and restricts movement of the rotating shaft in the axial direction.
A sliding bearing comprising a metal sliding surface of the thrust bearing portion provided with a crowning surface having a curved surface at least on the outer peripheral side.   A sliding bearing characterized in that the radial bearing portion and the thrust bearing portion are halved bearings having a semicircular cross section.

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