JP2020023995A - Bearing structure of crankshaft - Google Patents

Abstract

To provide a bearing structure of a crankshaft which can lower a temperature of a lower bearing.SOLUTION: A bearing structure 20 of a crankshaft comprises: a lower bearing 31 for pivoting a crank spindle 11 from a lower side; an upper bearing 32 for pivoting the crank spindle from an upper side; a lower housing 41 in which a first recess 45 for accommodating the lower bearing is formed; and an upper housing 42 in which a second recess 46 for accommodating the upper bearing is formed. Oil supplied between and among the lower bearing, the upper bearing and the crank spindle is leaked into a region between a crank web 12 and a web side face 47 of the lower housing. An oil passage 50 for introducing a part of the oil which is leaked into the region between the crank web and the web side face of the lower housing to a portion opposing a back face 34a of the lower bearing in the first recess is formed at the lower housing.SELECTED DRAWING: Figure 5

Description

  The present disclosure relates to a crankshaft bearing structure.

  For example, as shown in Patent Document 1, as a bearing structure of a crankshaft of an engine, a lower bearing that supports the crankshaft of the crankshaft from below, an upper bearing that supports the crankshaft from above, A lower housing provided with a first recess for accommodating a lower bearing (a bearing cap in Patent Document 1) and an upper housing provided with a second recess for accommodating an upper bearing (a cylinder block in Patent Document 1). Things are known. In such a bearing structure, oil is supplied between the lower bearing and the upper bearing and the crankshaft, and the oil lubricates the crankshaft.

  In general, in the above-described bearing structure, oil supplied between the bearings (the lower bearing and the upper bearing) and the crankshaft is supplied from the portion of the mating surface between the lower bearing and the upper bearing in the axial direction of the crankshaft. To the area between the crank web of the crankshaft and the side of the lower housing facing the crank web (web side).

Japanese Utility Model Publication No. 62-68017

  By the way, in the above-described bearing structure, if the temperature of the lower bearing can be reduced, the sliding resistance of the crankshaft can be reduced to improve the fuel efficiency of the engine. Therefore, there is a demand for a technology capable of lowering the temperature of the lower bearing.

  The present disclosure has been made in view of the above, and an object of the present disclosure is to provide a crankshaft bearing structure capable of lowering the temperature of a lower bearing.

  In order to achieve the above object, a crankshaft bearing structure according to an aspect of the present invention includes a lower bearing that supports a crank main shaft of an engine crankshaft from below and an upper bearing that supports the crank main shaft from above. And a lower housing provided with a first recess accommodating the lower bearing, and an upper housing provided with a second recess accommodating the upper bearing, wherein the lower bearing, the upper bearing, the crank main shaft, Wherein the oil supplied between the lower housing and the lower housing leaks into a region between the crank web of the crankshaft and a web side surface of the lower housing facing the crank web. The oil leaking into the area between the crank web and the side of the web of the lower housing. Part, wherein the oil passage for introducing into a portion facing the rear surface of the lower bearing in the first recess is provided in the.

  According to the above-described crankshaft bearing structure, the temperature of the lower bearing can be reduced.

FIG. 2 is a schematic configuration diagram illustrating a configuration around a crankshaft of the engine according to the first embodiment. 1 is a schematic configuration diagram illustrating an overall configuration of a bearing structure according to Embodiment 1. FIG. FIG. 3 is a schematic exploded view of the bearing of FIG. 2. FIG. 3 is a schematic exploded view of the housing of FIG. 2. FIGS. 5A to 5C are schematic diagrams illustrating details of the lower housing according to the first embodiment. FIGS. 6A and 6B are schematic diagrams for explaining the flow of oil in the oil passage and the oil discharge passage according to the first embodiment. FIG. 9 is a schematic top view for explaining a bearing structure according to a second embodiment.

(Embodiment 1)
Hereinafter, a crankshaft bearing structure 20 according to the first embodiment (hereinafter, simply referred to as a bearing structure 20) will be described with reference to the drawings. The drawings are schematically illustrated so that the configuration is easy to understand, and the ratio of the plate thickness, width, length, and the like of each member does not always match the ratio of the actual product. FIG. 1 is a schematic configuration diagram illustrating a peripheral configuration of a crankshaft 10 of an engine 1 having a bearing structure 20 according to the present embodiment. In the X-Y-Z orthogonal coordinates shown in FIG. 1, the Z direction corresponds to the upper side, and the -Z direction corresponds to the lower side (the direction in which gravity acts).

  In the present embodiment, a diesel engine is used as an example of the engine 1. However, the type of the engine 1 is not limited to this, and for example, a gasoline engine or the like can be used. The engine 1 includes a cylinder block having a cylinder, a cylinder head disposed on an upper portion of the cylinder block, a piston disposed on the cylinder, a crankshaft 10 connected to the piston via a connecting rod, and a crankshaft 10. And a bearing structure 20 that supports the shaft. Although the number of cylinders is not particularly limited, the engine 1 according to the present embodiment includes, for example, four cylinders # 1 to # 4 in total. The engine 1 according to the present embodiment includes, as an example, a plurality (specifically, five) of the bearing structures 20.

  The crankshaft 10 includes a crank main shaft 11, a crank web 12, and a crank pin 13. The crank main shaft 11 is supported by a bearing structure 20 and rotates about an axis 14 of the crank main shaft 11 as a center of rotation. As described above, since the engine 1 according to the present embodiment includes the cylinders # 1 to # 4, a total of four crank pins 13 are provided so as to correspond to the cylinders # 1 to # 4. Have been. The # 1 to # 4 crank pins 13 are connected to pistons arranged in the respective cylinders via connecting rods. The crank web 12 is a part that connects the crank spindle 11 and the crank pin 13 and rotates about an axis 14 of the crank spindle 11 as a center of rotation.

  Although not shown, the engine 1 is also provided with an oil supply mechanism for supplying lubricating oil to parts to be lubricated such as the crankshaft 10 and a valve operating mechanism (such as a cam). The oil supply mechanism includes an oil pan disposed below the crankshaft 10, an oil pump that sucks up oil stored in the oil pan and feeds the oil, and an oil pump that feeds the oil pumped by the oil pump. And an oil passage for supplying the oil to the engine.

  Next, the configuration of the bearing structure 20 will be described by taking the bearing structure 20 that supports the crankshaft 11 between the # 1 cylinder and the # 2 cylinder among the plurality of bearing structures 20 as an example. . FIG. 2 is a schematic configuration diagram illustrating the overall configuration of the bearing structure 20, and specifically illustrates a cross section taken along line AA of FIG. The bearing structure 20 according to the present embodiment includes a bearing 30 and a housing 40 that accommodates the bearing 30. FIG. 3 is a schematic exploded view of the bearing 30 of FIG. FIG. 4 is a schematic exploded view of the housing 40 of FIG.

  2 and 3, bearing 30 is a so-called sliding bearing. Specifically, the bearing 30 includes a lower bearing 31 that supports the crank main shaft 11 from below and an upper bearing 32 that supports the crank main shaft 11 from above. The lower bearing 31 and the upper bearing 32 are each formed of a semi-cylindrical bearing metal.

  Referring to FIG. 3, the inner surface of lower bearing 31 (the surface facing the outer peripheral surface of crank main shaft 11) is a bearing surface 33a that supports crank main shaft 11 from below. The surface of the lower bearing 31 opposite to the bearing surface 33a is referred to as a back surface 34a. Similarly, the inner surface of the upper bearing 32 is a shaft support surface 33b that supports the crank main shaft 11 from above. The surface of the upper bearing 32 opposite to the bearing surface 33b is referred to as a back surface 34b.

  Referring to FIGS. 2 and 4, housing 40 includes a lower housing 41 and an upper housing 42. Referring to FIG. 4, a first recess 45 for housing lower bearing 31 is provided on upper surface 43 of lower housing 41. The lower surface 44 of the upper housing 42 is provided with a second concave portion 46 that accommodates the upper bearing 32. Specifically, the first concave portion 45 has a semi-cylindrical shape, and the lower bearing 31 is accommodated in the semi-cylindrical first concave portion 45. Similarly, the second concave portion 46 has a semi-cylindrical shape, and the upper bearing 32 is housed inside the semi-cylindrical second concave portion 46.

  Referring to FIG. 2, housing 40 supports bearing 30 such that upper surface 43 of lower housing 41 and lower surface 44 of upper housing 42 are aligned with each other. When the lower housing 41 and the upper housing 42 are fitted together, a clearance (clearance) is provided between the bearing surfaces 33 a and 33 b of the bearing 30 and the outer peripheral surface of the crankshaft 11. The oil pumped from the oil pump is supplied to a portion (gap) between the bearing surfaces 33a and 33b of the bearing 30 and the outer peripheral surface of the crankshaft 11, and is used for lubrication of the crankshaft 11.

  Oil supplied to a portion between the bearing surfaces 33a and 33b of the bearing 30 and the outer peripheral surface of the crankshaft 11 is supplied to the mating surface of the lower bearing 31 and the upper bearing 32 (the upper bearing 32 and the lower bearing 31 are joined together). Of the crank main shaft 11, and leaks into a region between the crank web 12 and the web side surface 47 (side surface facing the crank web 12) of the lower housing 41. The flow of the oil leaking into the region between the crank web 12 and the web side surface 47 will be described later in detail (FIG. 6).

  Subsequently, details of the lower housing 41 will be described. FIGS. 5A to 5C are schematic diagrams for explaining details of the lower housing 41. Specifically, FIG. 5A is a schematic front view of the lower housing 41, and FIG. 5B is a schematic top view of the lower housing 41. FIG. 5C is a schematic side view of the lower housing 41. Specifically, FIG. 5C schematically illustrates a state where the lower housing 41 is viewed from the direction B in FIG. 5B. With reference to FIGS. 5A to 5C, an oil passage 50 and an oil discharge passage 60 are provided in the lower housing 41.

The oil passage 50 transfers a part of the oil leaked to the region between the crank web 12 and the web side surface 47 (the side surface facing the crank web 12) of the lower housing 41 to the back surface 34a of the lower bearing 31 in the first recess 45. The oil passage is configured to be introduced into a portion facing the oil passage. The specific configuration of the oil passage 50 is not particularly limited as long as it has such a function, but the oil passage 50 according to the present embodiment has the following configuration as an example. .

  Specifically, the oil passage 50 according to the present embodiment includes a first oil passage 51 and a second oil passage 52. One end of the first oil passage portion 51 is open to the web side surface 47 of the lower housing 41, and the other end communicates with the second oil passage portion 52. Specifically, with reference to FIG. 5B, the first oil passage portion 51 according to the present embodiment is located on one side (the portion of the axis 14) of the lower housing 41 relative to the central portion (the portion of the axis 14) when viewed from above. 5 (b). The first oil passage portion 51 penetrates the lower housing 41 so as to extend in a direction along the axis 14, thereby communicating the web side surface 47 of the lower housing 41 with the second oil passage portion 52.

  The second oil passage portion 52 is provided in a groove shape in a portion of the first recess 45 facing the back surface 34 a of the lower bearing 31. Specifically, the second oil passage portion 52 is configured by a semicircular groove provided in a portion of the first recess 45 facing the back surface 34 a of the lower bearing 31.

  The oil discharge passage 60 is a passage for discharging the oil in the second oil passage portion 52 to the outside of the lower housing 41. The specific configuration of the oil discharge passage 60 is not particularly limited as long as it has such a function, but the oil discharge passage 60 according to the present embodiment has the following configuration as an example. ing.

  Specifically, one end of the oil discharge passage 60 communicates with the second oil passage portion 52, and the other end of the outer peripheral side surface of the lower housing 41 is parallel to the axis 14 (the side parallel to the axis line 48). Open). More specifically, the oil discharge passage 60 is opposite to the other side (the side where the first oil passage portion 51 is disposed) than the center portion in the top view of the lower housing 41 (FIG. 5B). Side). The oil discharge passage 60 penetrates the lower housing 41 so as to extend in a direction perpendicular to the axis 14, and communicates the second oil passage 52 with the axis parallel side surface 48.

  FIGS. 6A and 6B are schematic diagrams for explaining the flow of oil in the oil passage 50 and the oil discharge passage 60. FIG. Specifically, FIG. 6 (a) schematically illustrates the flow of oil in the lower housing 41 of FIG. 5 (a), and FIG. 6 (b) illustrates the lower housing 41 of FIG. 5 (b). 3 schematically illustrates the flow state of the oil in FIG. As described above, the oil supplied to the portion between the bearing surfaces 33a and 33b of the bearing 30 and the outer peripheral surface of the crankshaft 11 is then removed from the portion of the mating surface between the upper bearing 32 and the lower bearing 31. A jet is ejected in the axial direction of the crankshaft 11 to form a region between the crank web 12 and the web side surface 47 of the lower housing 41 (this is constituted by a gap provided between the crank web 12 and the web side surface 47). Area).

  Part of the oil that has leaked into the region between the crank web 12 and the web side surface 47 flows into the first oil passage portion 51 of the oil passage 50, and then flows into the second oil passage portion 52. By doing so, the rear surface 34a of the lower bearing 31 is cooled. Then, the oil in the second oil passage portion 52 passes through the oil discharge passage 60 and is discharged to the outside of the lower housing 41. The oil discharged through the oil discharge passage 60 to the outside falls and is collected by the oil pan.

As described above, the bearing structure 20 described with reference to FIGS. 2 to 6 uses the crank main shaft 11 between the # 1 cylinder and the # 2 cylinder among the plurality of bearing structures 20 shown in FIG. The bearing structure 20 is supported. Since the configuration of the other bearing structure 20 among the plurality of bearing structures 20 is the same as the bearing structure 20 described with reference to FIGS. 2 to 6, the description of the configuration of the other bearing structure 20 is omitted.

  In addition, only a part of the bearing structures among the plurality of bearing structures that support the crank main shaft 11 is the bearing structure 20 (the bearing structure including the oil passage 50 and the oil discharge passage 60) as described with reference to FIGS. 20), and the other bearing structure may not include the oil passage 50 and the oil discharge passage 60. That is, at least one bearing structure among the plurality of bearing structures that support the crankshaft 11 only needs to be the bearing structure 20 described with reference to FIGS.

  According to the bearing structure 20 according to the present embodiment as described above, a part of the oil leaked to the region between the crank web 12 and the web side surface 47 of the lower housing 41 is transferred to the oil passage 50 (the first oil passage). The portion 51 and the second oil passage portion 52) can be introduced into the portion of the first recess 45 facing the back surface 34a of the lower bearing 31, and the introduced oil cools the back surface 34a of the lower bearing 31. it can. Thereby, the temperature of the lower bearing 31 can be reduced.

  Further, according to the present embodiment, the temperature of the lower bearing 31 can be reduced, so that the temperature of the oil between the lower bearing 31 and the crankshaft 11 can be reduced. Thus, the minimum oil film thickness between the bearing 30 and the crankshaft 11 can be increased, so that the sliding resistance of the crankshaft 11 during rotation of the crankshaft 10 can be reduced. As a result, the fuel efficiency of the engine 1 can be improved.

  Further, according to the present embodiment, as described above, the minimum oil film thickness between the bearing 30 and the crankshaft 11 can be increased, so that the bearing 30 and the crankshaft 11 can be locally contacted. It can also be suppressed. As a result, abnormal wear and seizure of the bearing 30 and the crankshaft 11 can be suppressed.

  Further, according to the present embodiment, since the lower housing 41 is provided with the oil discharge passage 60, the oil in the second oil passage portion 52 can be effectively discharged to the outside of the lower housing 41. This makes it easier for new oil to flow into the second oil passage portion 52, so that the cooling effect of the oil on the lower bearing 31 can be enhanced.

  However, the lower housing 41 may not include the oil discharge passage 60. Also in this case, it is possible to introduce oil into the portion of the first recess 45 facing the back surface 34a of the lower bearing 31 by the oil passage 50, whereby it is possible to lower the temperature of the lower bearing 31. It is.

(Embodiment 2)
FIG. 7 is a schematic top view for explaining the bearing structure 20a according to the second embodiment. Specifically, FIG. 7 schematically illustrates the same portion of the lower housing 41a of the bearing structure 20a as in FIG. 5B described above. Here, the bearing structure 20 a according to the present embodiment relates to a bearing structure that supports the crank main shaft 11, which is sandwiched between the crank webs 12 on both sides of the crank main shaft 11 of the crank shaft 10. Specifically, referring to FIG. 1 described above, a bearing structure 20a according to the present embodiment includes a portion between cylinders # 1 and # 2, a portion between cylinders # 2 and # 3, or This is a bearing structure arranged at a portion between the cylinders # 3 and # 4.

  As shown in FIG. 7, the bearing structure 20a further includes an oil passage 50a and an oil discharge passage 60a in addition to the oil passage 50 and the oil discharge passage 60. The other configuration of the bearing structure 20a is the same as that of the bearing structure 20, and the description of the other configuration will be omitted.

  The oil passage 50a allows a portion of the oil leaking into the region between the crank web 12 and the web side surface 47a of the lower housing 41a (which is the web side surface opposite to the web side surface 47) to pass through the first recess. 45 is an oil passage configured to be introduced into a portion of the lower bearing 31 facing the back surface 34a of the lower bearing 31. Specifically, the oil passage 50a includes a first oil passage 51a and a second oil passage 52a.

  One end of the first oil passage portion 51a is open to the web side surface 47a of the lower housing 41a, and the other end communicates with the second oil passage portion 52a. The second oil passage portion 52a is provided in a groove shape (specifically, a semicircular groove shape) in a portion of the first recess 45 facing the back surface 34a of the lower bearing 31.

  The oil discharge passage 60a is a passage for discharging the oil in the second oil passage 52a to the outside of the lower housing 41a. Specifically, as an example, the oil discharge passage 60a according to the present embodiment has one end communicating with the second oil passage portion 52a and the other end opening to the axis parallel side surface 48 of the lower housing 41a. .

  Subsequently, the operation and effect of the present embodiment will be described. The oil supplied between the bearing 30 and the crankshaft 11 not only leaks into the region between the crank web 12 arranged on one side of the bearing structure 20a and the web side surface 47 of the lower housing 41a, It also leaks into the area between the crank web 12 located on the other side of the bearing structure 20a and the web side 47a of the lower housing 41a.

  According to the present embodiment, part of the oil that has leaked into the region between the crank web 12 arranged on one side of the bearing structure 20a and the web side surface 47 of the lower housing 41a is controlled by the oil passage 50. Then, the oil is introduced into a portion of the first recess 45 facing the back surface 34a of the lower bearing 31, and the introduced oil can cool the back surface 34a of the lower bearing 31. In addition, a part of the oil leaking into the region between the crank web 12 arranged on the other side of the bearing structure 20a and the web side surface 47a of the lower housing 41a is also reduced by the oil passage 50a in the lower portion of the first recess 45. The oil is introduced into a portion facing the back surface 34a of the bearing 31, and the introduced oil can cool the back surface 34a of the lower bearing 31. Thereby, the temperature of the lower bearing 31 can be effectively reduced.

  As a result, according to the present embodiment, the temperature of the oil between the lower bearing 31 and the crankshaft 11 can be effectively reduced. As a result, the minimum oil film thickness between the bearing 30 and the crankshaft 11 can be effectively increased, so that the sliding resistance of the crankshaft 11 during rotation of the crankshaft 10 can be effectively reduced. it can. As a result, the fuel efficiency of the engine 1 can be effectively improved. In addition, local contact between the bearing 30 and the crankshaft 11 can be effectively suppressed. As a result, abnormal wear and seizure of the bearing 30 and the crankshaft 11 can be effectively prevented. Can be suppressed.

  In the present embodiment (FIG. 7), the first oil passage portion 51 and the first oil passage portion 51a are arranged on the same side (the X direction side in the figure) with respect to the central portion when viewed from above. It is not limited to this. For example, the first oil passage portion 51 and the first oil passage portion 51a may be arranged on different sides with respect to a central portion in a top view. As a specific example, for example, the first oil passage portion 51 may be arranged on the X direction side of the center portion, and the first oil passage portion 51a may be arranged on the −X direction side of the center portion. In this case, the oil discharge passage 60a is disposed on the X direction side of the center.

  Embodiments 1 and 2 described above are presented as examples, and do not limit the scope of the invention. Embodiments 1 and 2 can be further variously modified and changed within the scope of the invention described in the claims.

DESCRIPTION OF SYMBOLS 1 Engine 10 Crankshaft 11 Crank main shaft 12 Crank web 20, 20 a Crankshaft bearing structure 30 Bearing 31 Lower bearing 32 Upper bearing 34 a, 34 b Back surface 40 Housing 41, 41 a Lower housing 42 Upper housing 43 Upper surface 44 Lower surface 45 First recess 46 Second concave portion 47 Web side surface 50, 50a Oil passage 51, 51a First oil passage 52, 52a Second oil passage 60, 60a Oil discharge passage

Claims (3)

A lower bearing that supports a crank main shaft of an engine crankshaft from below, an upper bearing that supports the crank main shaft from above, a lower housing provided with a first recess for housing the lower bearing, An upper housing provided with a second recess for accommodating an upper bearing, wherein oil supplied between the lower bearing and the upper bearing and the crankshaft is provided between the crank web of the crankshaft and the lower housing. In a bearing structure of a crankshaft, which leaks into a region between a web side surface which is a side surface facing the crank web,
The lower housing has an oil that introduces a part of the oil that has leaked into a region between the crank web and the side surface of the web of the lower housing into a portion of the first recess that faces the back surface of the lower bearing. A crankshaft bearing structure, characterized in that a passage is provided. The oil passage includes a first oil passage portion and a second oil passage portion,
One end of the first oil passage is open to the side of the web of the lower housing, the other end of the first oil passage communicates with the second oil passage,
2. The crankshaft bearing structure according to claim 1, wherein the second oil passage portion is provided in a groove shape at a portion of the first recess facing the rear surface of the lower bearing. 3.   3. The crankshaft bearing structure according to claim 2, wherein the lower housing further includes an oil discharge passage for discharging the oil in the second oil passage to the outside of the lower housing.

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