The present invention relates to a bearing for use in an internal combustion engine of an automobile or the like.
A bearing that employs bimetal, which has a lining layer made of a copper-based or an aluminum-based bearing alloy on a metal backing made of steel or the like, is known as a so-called main bearing or connecting rod bearing used in an internal combustion engine (engine) of an automobile or the like (e.g., see JP 2013-167280). Also, although not for use in an internal combustion engine, a bearing made of resin is known as a bearing for use in office equipment or the like (e.g., see JP 2008-19880 and JP 2000-87954).
One characteristic that is desired for an internal combustion engine in an automobile is an increase in the speed of rise in lubricant temperature during cold starting, or in other words an improvement in the so-called warm-up characteristic. However, when using a bearing made of metal as described in JP 2013-167280, heat escapes from the lubricant via the bearing due to the relatively high thermal conductivity thereof, and there has been a problem in that the temperature of the lubricant does not rise easily. The bearings described in JP 2008-19880 and JP 2000-87954 are used in a non-lubricated environment such as in office equipment, and have had the problem of not being able to be used as bearings for an internal combustion engine that are used along with a lubricant.
In view of this, the present invention relates to technology for improving mainly the warm-up characteristic with a bearing for an internal combustion engine.
The present invention provides an internal combustion engine bearing including: a bearing main body that is formed from a resin, has a semicircular tube shape, and has an inner circumferential surface that is to slide over an opposing shaft and an outer circumferential surface that is to come into contact with a housing.
The bearing main body may include a layer formed from a thermosetting resin.
The bearing main body may include a layer formed from a thermoplastic resin.
The bearing main body may include a layer formed from a fiber reinforced resin.
This internal combustion engine bearing may have a first layer that is formed from a thermosetting resin and includes the outer circumferential surface; and a second layer that is formed from a thermoplastic resin and includes the inner circumferential surface.
A thickness of the first layer may be greater than or equal to 80% of a thickness of the bearing main body.
The bearing main body may have an oil passage between the first layer and the second layer.
The present invention also provides a method of manufacturing an internal combustion engine bearing, including: producing a slurry by stirring a material that contains a resin in water; dehydrating the produced slurry; and molding the dehydrated slurry by applying pressure and heat in a mold.
The present invention also provides a method of manufacturing an internal combustion engine bearing, including: forming a first layer from a thermosetting resin; and forming a second layer by coating the first layer with a thermoplastic resin.
The present invention also provides a method of manufacturing an internal combustion engine bearing, including: forming a first layer by injecting a thermosetting resin into a first mold; arranging the formed first layer into a second mold; and forming a second layer by injecting a thermoplastic resin into the second mold in which the first layer is arranged.
The present invention also provides a method of manufacturing an internal combustion engine bearing, including: forming a first layer by injecting a thermosetting resin into a portion of an interior space of a mold; and forming a second layer by injecting a thermoplastic resin between the mold and the first layer.
The present invention also provides a method of manufacturing an internal combustion engine bearing, including: forming a first layer by using a first male mold to press a thermosetting resin powder or granules arranged in a female mold; and forming a second layer by using a second male mold to press a thermoplastic resin powder or granules arranged so as to be overlaid on the first layer formed in the female mold.
According to the present invention, it is possible to improve the warm-up characteristic with a bearing for an internal combustion engine. Also, it is possible to improve the mechanical strength compared to the case where the internal combustion engine bearing is entirely made of a thermoplastic resin, and it is possible to improve the sliding characteristic of the sliding surface that slides over the shaft in comparison with the case where the bearing is entirely made of a thermosetting resin.
Examples of the thermosetting resin include thermosetting polyimide resin (PI), phenol resin (PF), urea resin (UF), melamine resin (MF), epoxy resin (EP), furan resin (FF), xylene resin (XF), alkyd resin (UP), silicone resin (SI), allyl resin (PDAP), and a material obtained by mixing fibers (glass fibers or carbon fibers) in these types of resin (so-called fiber-reinforced plastic (fiber reinforced resin), FRP).
Examples of the thermoplastic resin include polyvinyl chloride resin (PVC), polyvinylidene chloride resin (PVdC), polyvinyl alcohol resin (PVA), polystyrene resin (PS), acrylonitrile styrene resin (AS), acrylonitrile-butadiene-styrene resin (ABS), polyethylene resin (PE), ethylene vinyl acetate copolymer resin (EVA), polypropylene resin (PP), polyacetal resin (POM), polymethylmethacrylate resin (PMMA), modified acrylic resin (MS), cellulose acetate resin (CA), polycarbonate resin (PC), polyester resin (PET, PTT, PBT, PEN, PBN), polyamide resin (PA), polyurethane resin (PU), fluoric resin (PTFE, FEP, PFA, etc.), polyamide-imide resin (PAD, polyphenylene sulfide (PPS), polyetheretherketone (PEEK), thermoplastic polyimide (TPI), polybenzimidazole (PBI), polyetherimide resin (PEI), polysulfone resin (PSF), polyethersulfone resin (PES), and polyarylate resin (PAR).
Due to being used in an internal combustion engine, the heat resistant temperature (e.g., continuous use temperature) of the resin is preferable greater than or equal to 180° C., and more preferably greater than or equal to 200° C. Also, from the viewpoint of improving the warm-up characteristic, the thermal conductivity of the resin is preferably less than or equal to 1 W/mK, and more preferably less than or equal to 0.5 W/mK. Also, in order to avoid adverse effects caused by moisture absorption, such as change in dimensions, the moisture absorption of the resin is preferably less than or equal to 0.2%. In the case of thermoplastic resin in particular, there is a problem that the glass transition point decreases due to moisture absorption, and therefore the moisture absorption is preferably less than or equal to 0.2%. Furthermore, from the viewpoint of suppressing expansion in the cylinder block, the coefficient of linear expansion of the resin is preferably less than or equal to 70×10−6.
Bearing main body 111 is entirely made of a resin, and therefore compared to the case where the bearing main body is made of a metal, heat less easily escapes from the lubricant to the housing via the bearing, and it is possible to improve the speed of rise in the lubricant temperature when the engine is cold started.
Bearing main body 111 is molded with a semicircular tube shape, and has inner circumferential surface 112 (sliding surface) that slides over crankshaft 1, and outer circumferential surface 113 that is in contact with the housing (not shown). The diameter φ of crankshaft 1 is 30 to 150 mm for example, and bearing main body 111 has an inner diameter that conforms to the diameter of crankshaft 1. Furthermore, bearing main body 111 has mating surface 114 and mating surface 115 that are in contact with semicircular tube-shaped bearing 12.
In this example, semicircular tube-shaped bearing 11 has oil groove 116 in inner circumferential surface 112. Oil groove 116 is a groove for supplying lubricant to the sliding surface and also holding supplied lubricant. Also, oil groove 116 is provided with at least one oil hole 117 that penetrates from outer circumferential surface 113 to inner circumferential surface 112. A portion of crankshaft 1 that is supported by semicircular tube-shaped bearing 11 is provided with an oil hole (not shown) at a position opposing oil groove 116. This oil hole penetrates to a portion of crankshaft 1 that is supported by connecting rod bearing 20. Lubricant is supplied to outer circumferential surface 113 of semicircular tube-shaped bearing 11 via an oil passage (not shown) that is provided in the cylinder block. Lubricant that has been supplied to outer circumferential surface 113 is supplied to inner circumferential surface 112 (sliding surface) via oil hole 117, and lubricates the main bearing. The lubricant on the sliding surface is supplied to the sliding surface of connecting rod bearing 20 via the oil hole of crankshaft 1.
Also, in this example, oil groove 116 is formed so as to extend the entire length in the sliding direction, from mating surface 114 to mating surface 115.
The depth of the oil groove is also not uniform, but rather increases in depth toward the central portion of bearing main body 111, and decreases in depth from the central portion toward the mating surfaces.
Furthermore, bearing main body 111 is provided with a crush relief. Crush relief refers to a “relief” provided over the entire width of bearing main body 111 in portions of inner circumferential surface 112 that are adjacent to mating surface 114 and mating surface 115.
In this example, fine grooves (microgrooves) that are finer than oil groove 116 are formed in a portion of inner circumferential surface 112 other than oil groove 116.
Also, bearing main body 111 has interference (so-called crush). In other words, bearing main body 111 has a longer diameter than a semicircle.
The description will now return to
Also, semicircular tube-shaped bearing 11 has so-called bulge. Bulge refers to setting the outer diameter dimension larger than the inner diameter of the housing in the free state (not attached to the housing) in a view from the axial direction. This bulge is 0.8 to 1.3 mm for example. Bulge has an effect of allowing the outer circumference of semicircular tube-shaped bearing 11 to conform to the inner circumference of the housing during attaching, and has an effect of preventing semicircular tube-shaped bearing 11 from moving away from or falling out of the housing during attachment.
A detailed description will not be given for semicircular tube-shaped bearing 12, which is the same as semicircular tube-shaped bearing 11 with the exception of not having an oil groove or an oil hole. A detailed description will not be given for connecting rod bearing 20 either, which is the same as main bearing 10 in that two semicircular tube-shaped bearings are used in a combined state. It should be noted that in connecting rod bearing 20, neither of the semicircular tube-shaped bearings has an oil groove or an oil hole. The two semicircular tube-shaped bearings of connecting rod bearing 20 are other examples of an internal combustion engine bearing according to the present invention.
Also, semicircular tube-shaped bearing 11 and semicircular tube-shaped bearing 12 may have a structure in which multiple resin layers are laminated in a direction of radiation from the axial center.
As shown in
Note that thickness t1 of first layer 1111 is desirably greater than or equal to 80% of thickness t of bearing main body 111. Accordingly, there is an improved possibility that bearing main body 111 withstands load received from crankshaft 1 or the like. Also, instead of a two-layer structure including first layer 1111 and second layer 1112, bearing main body 111 may include three or more resin layers that are laminated.
Also, bearing main body 111 may have oil passage 116a between layers.
As shown in
Accordingly, lubricant supplied from an oil passage (not shown) provided in the cylinder block passes through oil holes 117b from outer circumferential surface 113 side, fills oil passage 116a, and then passes through oil holes 117a and reaches inner circumferential surface 112. Accordingly, sliding surfaces of crankshaft 1 and bearing main body 111 (inner circumferential surface 112) slide over each other.
Note that the positions of oil holes 117a and oil holes 117b may match, but are not required to match, as shown in
Several methods can be applied as methods for manufacturing main bearing 10 and connecting rod bearing 20.
In this example, bearings are molded one at a time by injection molding, compression molding, or the like. The oil groove, oil holes, and fine grooves may be molded by forming an oil groove, oil holes, and fine grooves in the mold in advance, or may be formed by performing cutting or the like after molding into the semicircular tube shape.
In step S11 shown in
In step S12 in
In step S13 shown in
Note that if resin is molded into a semicircular tube shape with the width of the completed bearing in step S11, step S12 shown in
Also, besides injection molding and compression molding, the molding in step S11 may be sheet forming. Here, “sheet forming” is a solid member manufacturing method that has a step in which a material containing resin is stirred in water to produce a slurry, a step in which the produced slurry is dehydrated, and a step in which the dehydrated slurry is molded by being pressed and heated in a mold.
In step S102, the above-described material is introduced into water and stirred or mixed to produce a slurry.
In step S103, the above-described slurry is supplied to a filter and dehydrated. Suction filtration, pressure filtration, or the like is applied as dehydration.
In step S104, the above-described dehydrated slurry is supplied to a mold and then pressed and heated, thus being molded into a predetermined shape, such as a semicircular tube shape.
When the resin molded body is molded by the sheet forming steps of step S101 to step S104 shown in
Also, in the case where the bearing has a laminated structure as shown in
A bearing having a laminated structure may be molded by performing coating as shown in
Also, a bearing that has a laminated structure may be molded by injection molding multiple resin pieces at different times as shown in
Also, a bearing having a laminated structure may be molded by so-called multicolor molding as shown in
In step S401 in
This multicolor molding is applicable to compression molding as well. In this case, step S402 described above can be omitted.
For example, in step S401 of
The first male mold is removed, and then in step S403, a thermoplastic resin powder or granules are introduced through the opening of the above-described female mold. The introduced thermoplastic resin is arranged so as to be overlaid on the first layer in the interior space of the female mold. A second male mold is then inserted into the opening of the female mold, and the resin is pressed. Accordingly, the thermoplastic resin hardens in the space between the first layer and the second male mold, and a second layer is formed. This second layer includes inner circumferential surface 112. The second male mold constitutes a second mold along with the female mold.
Note that the second male mold may be different from or the same as the first male mold. Also, the order in which the thermosetting resin and the thermoplastic resin are introduced may be reversed. Moreover, the resin that is molded in the latter stage may be introduced before the resin molded in the earlier stage has completely hardened.
In step S21, resin is molded into a circular tube shape.
In step S22, the circular tube-shaped resin molded body is bisected by performing cutting in the axial direction. Two semicircular tube-shaped resin molded bodies are obtained.
Note that similarly to the second example described above, if resin is molded into a circular tube shape having the width of the completed bearing in step S21 in
Also, the molding in step S21 of
Also, in the case where the bearing is to have a laminated structure, similarly to the second example, various methods can be applied to the molding in step S21 of
The present invention is not limited to the embodiment described above, and various modifications can be carried out. The following describes several variations. Two or more of the following variations may be used in combination.
The specific shape of the bearing is not limited to the shape illustrated in the embodiment. For example, at least one of the oil groove, the oil holes, the fine grooves, the oil relief, the crush relief, and the claw may be omitted. Alternatively, at least one of an oil groove and oil holes may be provided in semicircular tube-shaped bearing 12 and connecting rod bearing 20. Also, the specific sizes of these elements are not limited to the sizes illustrated in the embodiment. Moreover, the specific shapes, number of, and positions of the oil groove and the oil holes are not limited to those illustrated in the embodiment. Furthermore, the semicircular tube-shaped bearing is not required to have a bulge.
In the embodiment, an example is described in which oil groove 116 extends from mating surface 114 to mating surface 115. However, the oil groove may be formed in only a portion in the circumferential direction. Also, the oil groove is not limited to being formed in the sliding surface (inner circumferential surface), and may be formed in the outer circumferential surface. In other words, it is sufficient that the oil groove is formed in at least one of the inner circumferential surface and the outer circumferential surface of the bearing main body.
Number | Date | Country | Kind |
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2015-110790 | May 2015 | JP | national |
This application is a U.S. National Stage Application of International Application No. PCT/JP2016/065705, filed on May 27, 2016, which claims priority to Japanese Application No. 2015-110790, filed on May 29, 2015. The entire disclosures of the above applications are incorporated herein by reference.
Filing Document | Filing Date | Country | Kind |
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PCT/JP2016/065705 | 5/27/2016 | WO | 00 |