JP2022136652A - Crankshaft bearing structure - Google Patents

Abstract

To provide a crankshaft bearing structure capable of discharging granular foreign matters from between a journal bearing and a crank journal, and of securing an appropriate hydraulic pressure even when using low-viscosity oil.SOLUTION: A crankshaft 1 of a crankshaft bearing structure has a plurality of crank journals 11 extending along an axial center Ax1 and arranged at intervals in a direction of the axial center Ax1. On each crank journal 11, the journal bearing is annularly mounted. The crank journal 11 has an outer peripheral face 11a running along an inner peripheral face of the journal bearing, and a recessed part 11b provided in a peripheral part of the crank journal 11 so as to be more recessed in a radial direction than the outer peripheral face 11a. The recessed part 11b is a site for trapping granular foreign matters entering between the crank journal 11 and the journal bearing.SELECTED DRAWING: Figure 4

Description

The present invention relates to an engine crankshaft bearing structure, and more particularly to a crank journal structure in a crankshaft.

A vehicle engine has a crankshaft for outputting rotational driving force, a cylinder block having a bearing portion that supports the crankshaft, and a cylinder head attached to the upper portion of the cylinder block. A journal bearing is interposed between the bearing portion of the cylinder block and the crank journal of the crankshaft. The journal bearing is configured by a combination of an upper journal bearing and a lower journal bearing each having a semi-annular shape when viewed from the front in the axial direction of the crankshaft. The upper journal bearing is arranged to cover the upper half of the outer peripheral surface of the crank journal, and the lower journal bearing is arranged to cover the lower half of the outer peripheral surface of the crank journal.

An oil hole is opened in the upper journal bearing. An oil gallery is connected to the oil hole of the upper journal bearing. Oil passes through the oil holes and is supplied between the inner peripheral surfaces of the upper and lower journal bearings and the outer peripheral surface of the crank journal. The oil supplied in this manner lubricates the inner peripheral surfaces of the upper and lower journal bearings and the outer peripheral surface of the crank journal.

In the conventional crankshaft bearing structure, grooves are formed in the inner peripheral surface of the upper journal bearing so as to extend in the circumferential direction. This groove functions (i) as a path for guiding part of the oil to the in-shaft oil passage provided to supply the adjacent crank pin, and (ii) between the lower journal bearing and the crank journal. In addition, (iii) particulate foreign matter (for example, metal powder) mixed with oil and entering between the journal bearing and the crank journal is removed from the journal bearing and the crank journal. It has a function as a guideway when discharging to the outside from between.

By the way, in recent years, in some cases, low-viscosity oil is used for the purpose of improving the fuel efficiency of the engine. In this way, when low-viscosity oil is used in the engine, the sliding resistance can be reduced, but when the oil becomes hot due to the engine being driven, etc., the oil pressure will drop, so an appropriate oil pressure is required. To ensure this, it is necessary to increase the load on the oil pump.

In order to deal with the drop in hydraulic pressure caused by using such low-viscosity oil, the grooves in the upper journal bearing, which were conventionally installed, were eliminated, and the flow resistance (pressure loss) was increased to ensure an appropriate hydraulic pressure in the lubrication circuit. can be considered.

However, if the grooves of the upper journal bearing are eliminated, it becomes difficult to discharge to the outside particulate foreign matter mixed with oil and entering between the journal bearing and the crank journal. It is conceivable to employ the structure disclosed in Japanese Patent Laid-Open No. 2002-200018 to address the problem of such particulate foreign matter.

Patent Literature 1 discloses a structure in which a filter for collecting particulate foreign matter is provided before oil is supplied between a crank journal and a journal bearing. In the structure disclosed in Patent Document 1, an oil hole is provided along the outer peripheral surface of the upper journal bearing in the cylinder block from the location where the filter is provided in the oil passage. The oil from which particulate matter has been collected by the filter passes through the oil hole and is supplied from the oil hole of the upper journal bearing to between the journal bearing and the crank journal.

JP 2010-168921 A

However, in the technique disclosed in Patent Document 1, since an oil hole is provided in a portion of the cylinder block along the outer peripheral surface of the upper journal bearing, the amount of oil leakage increases, and in order to secure an appropriate hydraulic pressure, the oil hole is provided. There is concern that the discharge amount of the oil pump must be increased.

The present invention is intended to solve the above problems, and it is possible to discharge particulate foreign matter from between the journal bearing and the crank journal, and even when low-viscosity oil is used. An object of the present invention is to provide a crankshaft bearing structure capable of ensuring an appropriate hydraulic pressure.

A crankshaft bearing structure according to one aspect of the present invention includes a crankshaft, a cylinder block, and a journal bearing. The crankshaft extends along a predetermined direction and has a plurality of crank journals spaced apart from each other in the predetermined direction.

The cylinder block has a plurality of bearing portions that are arranged to surround radially outer sides of the plurality of crank journals and that rotatably support the crankshaft. The journal bearing is annularly mounted on each of the plurality of crank journals between each of the plurality of crank journals and each of the plurality of bearing portions in a state in which the crankshaft is rotatable.

In the crankshaft bearing structure according to this aspect, the cylinder block further has an oil passage. In the crankshaft bearing structure according to this aspect, at least a portion of the crank journals among the plurality of crank journals has a diameter from the outer peripheral surface along the inner peripheral surface of the journal bearing in a portion of the crank journal in the circumferential direction. It is provided so as to be recessed inward in the direction, and has a dot-like or groove-like recess extending in the predetermined direction in plan view from the radially outer side. Further, in the crankshaft bearing structure according to this aspect, the journal bearing that is ring-mounted on the at least part of the crank journal is connected to the oil passage at the top, and the oil from the oil passage is transferred to the journal bearing and the journal bearing. an oil hole for supplying oil between the crankshaft and the crankshaft; an inner peripheral surface, which is a rotating surface generated with a straight line parallel to the rotation axis of the crankshaft as a generatrix; and grooves extending in the predetermined direction on the inner peripheral surface. and

In the crankshaft bearing structure according to the aspect described above, the recess is provided on the outer peripheral surface of at least a portion of the crank journal. Therefore, even if particulate foreign matter enters between the at least one crank journal and the journal bearing, the particulate foreign matter is collected by the recess as the crankshaft rotates. Journal bearings corresponding to at least some of the crank journals are formed with grooves extending in the predetermined direction (direction in which the crankshaft extends). Therefore, the particulate foreign matter collected in the recess of the crank journal is ejected into the groove of the journal bearing by centrifugal force when the recess and the groove of the journal bearing are connected by rotation of the crankshaft. The particulate foreign matter is then expelled to the outside by the flow of oil.

In the crankshaft bearing structure according to the above aspect, the inner peripheral surface of the journal bearing that is ring-mounted on at least one of the crank journals is formed of a surface of rotation generated with the straight line as the generatrix. In other words, in the crankshaft bearing structure according to this aspect, the inner peripheral surface of the journal bearing that is ring-mounted on at least a portion of the crank journal does not have circumferential grooves unlike the prior art. Further, in the crankshaft bearing structure according to this aspect, even if the inner peripheral surface of the journal bearing that is ring-mounted on the at least part of the crank journal does not have a groove in the circumferential direction, the at least one By providing a concave portion on the outer peripheral surface of the crank journal, it is possible to discharge the intruded granular foreign matter to the outside. In addition, since the recessed portion of the crank journal is provided only partially in the circumferential direction, even when low-viscosity oil is used, it is difficult for the oil pressure to drop.

In the crankshaft bearing structure according to the above aspect, the recess in the at least part of the crank journal is a groove-shaped recess extending in the predetermined direction, and both ends of the recess extend in the predetermined direction from the at least one crank journal. It may be arranged inside the both side ends of the crank journal of the part.

In the crankshaft bearing structure according to the aspect described above, both end portions of the recess are arranged inside the both end portions of the crank journal in the predetermined direction. Therefore, in the crankshaft bearing structure according to the aspect described above, it is possible to suppress the oil in the recessed portion of the crank journal from leaking from both ends of the crank journal. Therefore, the crankshaft bearing structure according to the aspect described above does not cause a decrease in hydraulic pressure.

In the crankshaft bearing structure according to the aspect described above, both end portions of the recess may be arranged rearward in the rotational direction of the crankshaft relative to the central portion of the recess.

In the crankshaft bearing structure according to the above aspect, the recess in the crank journal is provided so that both end portions are located rearward in the rotational direction of the crankshaft relative to the central portion. For this reason, the particulate foreign matter that has entered the recess moves to both end portions of the recess due to the flow of oil that accompanies the rotation of the crankshaft. Therefore, the crankshaft bearing structure according to the aspect described above is more advantageous in discharging the particulate foreign matter that has entered between the crank journal and the journal bearing to the outside.

In the crankshaft bearing structure according to the aspect described above, the bottom surface of the recess may be formed such that the radial depth at the both end portions is shallower than that at the central portion.

In the crankshaft bearing structure according to the above aspect, the radial depth of the concave portion is shallower at both end portions than at the central portion. For this reason, the particulate foreign matter collected in the recess moves radially outward toward the journal bearing as it moves toward both ends of the recess due to the flow of oil that accompanies the rotation of the crankshaft. Therefore, in the crankshaft bearing structure according to the above aspect, when the concave portion and the groove of the journal bearing are connected by the rotation of the crankshaft, the particulate foreign matter is easily discharged into the groove of the journal bearing.

In the crankshaft bearing structure according to the aspect described above, the bottom surface of the recess may be formed such that the bottom surface of the recess is shallower at the rear side in the rotational direction than at the front side in the rotational direction.

In the crankshaft bearing structure according to the above aspect, the radial depth of both ends of the recess is shallower on the rear side than on the front side. For this reason, in the crankshaft bearing structure according to the above aspect, the particulate foreign matter collected in the recess moves toward the rear in the rotational direction of both ends due to the flow of oil accompanying the rotation of the crankshaft, and moves toward the journal bearing. Move radially outward to get closer. Therefore, in the crankshaft bearing structure according to the above aspect, when the concave portion and the groove of the journal bearing are connected by the rotation of the crankshaft, the particulate foreign matter is easily discharged into the groove of the journal bearing.

In the crankshaft bearing structure according to the above aspect, the journal bearing may be composed of an upper journal bearing and a lower journal bearing, each of which has a semi-annular shape in a front view from the predetermined direction. Further, in the crankshaft bearing structure according to the above aspect, each of the upper journal bearing and the lower journal bearing has a circumferential end face that is oblique to the circumferential direction of the journal bearing and that extends in the predetermined direction. It may have a sloped portion extending along it. Furthermore, in the crankshaft bearing structure according to the above aspect, the groove in the journal bearing is formed when the circumferential end of the upper journal bearing and the circumferential end of the lower journal bearing are butted against each other. It may be configured by a gap between the slope portions.

In the crankshaft bearing structure according to the above aspect, the journal bearing is constituted by the upper journal bearing and the lower journal bearing, each having a semi-annular shape, and the groove is a gap between the slopes formed at the abutting portions. Therefore, in the crankshaft bearing structure according to the aspect described above, it is possible to easily mount the journal bearing on the crank journal. Further, in the crankshaft bearing structure according to the above aspect, even if the inner peripheral surfaces of the upper journal bearing and the lower journal bearing are not subjected to machining or the like, the particulate foreign matter can be discharged to the outside through the gap between the abutting portions. is possible.

In the crankshaft bearing structure according to the aspect described above, the recesses in the at least one portion of the crank journal may be provided at two locations on the circumference so as to face each other in the radial direction.

In the crankshaft bearing structure according to the above aspect, the recessed portions of the crank journal are provided at two locations on the circumference. Therefore, in the crankshaft bearing structure according to the aspect described above, it is possible to collect particulate foreign matter with high efficiency as compared with the case where the concave portion is provided only at one location on the circumference. It should be noted that if the concave portions are provided at three or more locations on the circumference, it is excellent in terms of collecting particulate foreign matter, but this is not preferable because it leads to a decrease in the rigidity of the crankshaft.

In the crankshaft bearing structure according to each of the above aspects, it is possible to discharge particulate foreign matter from between the journal bearing and the crank journal, and to ensure an appropriate hydraulic pressure even when low-viscosity oil is used. is.

1 is a schematic diagram showing a crankshaft bearing structure according to an embodiment; FIG. (a) is a perspective view showing the structure of journal bearings arranged for #1, 3 and 5 crank journals, and (b) is a perspective view of the journal bearings arranged for #2 and #4 crank journals. It is a perspective view which shows a structure. It is a figure which expands and shows the A section of Fig.2 (a). FIG. 4 is a partial perspective view showing part of the crankshaft; FIG. 5 is a plan view showing a B2 portion of FIG. 4; FIG. 6 is a sectional view showing a section taken along the line VI-VI of FIG. 5; 6 is a cross-sectional view showing a VII-VII cross section of FIG. 5; FIG. FIG. 6 is a sectional view showing the VIII-VIII line section of FIG. 5; (a) to (d) are schematic diagrams sequentially showing an example of movement patterns of a particulate foreign matter that has entered a concave portion. (a) is a cross-sectional view showing a state in which a particulate foreign matter has entered a gap provided at the abutting portion of an upper journal bearing and a lower journal bearing; It is a top view which shows the state which carries out. (a) is a plan view showing the structure of a recess provided in a crank journal according to Modification 1; (b) is a plan view showing the structure of a recess provided in a crank journal according to Modification 2; 8C is a plan view showing the structure of a recess provided in the crank journal according to Modification 3. FIG. FIG. 12 is a cross-sectional view showing the structure of a recess provided in a crank journal according to Modification 4;

EMBODIMENT OF THE INVENTION Below, embodiment of this invention is described, considering drawing into consideration. In addition, the form described below is an example of the present invention, and the present invention is not limited to the following forms except for its essential configuration.

1. Schematic Configuration of Crankshaft Bearing Structure 100 A schematic configuration of a crankshaft bearing structure 100 according to the present embodiment will be described with reference to FIG.

As shown in FIG. 1, the crankshaft bearing structure 100 comprises a crankshaft 1 and a plurality of journal bearings 36-45. The crankshaft bearing structure 100 also includes an oil gallery (oil passage) 46 formed in a cylinder block (not shown) and an oil pump 47 that sends oil to the oil gallery 46 . The cylinder block also has bearings that rotatably support the crankshaft 1 (not shown).

The crankshaft 1 extends along an axis (rotational axis) Ax1. The direction in which the axis Ax1 extends in the present embodiment corresponds to the "predetermined direction", which is the cylinder row direction of the engine. The crankshaft 1 has a plurality of crank journals 11 to 15 spaced apart from each other in the direction along the axis Ax1. The crankshaft 1 also has crank pins 24-27 arranged between adjacent crank journals 11-15 in the direction along the axis Ax1.

In the crankshaft 1, the crank journals 11-15 and the crank pins 24-27, which are adjacent in the direction in which the axis Ax1 extends, are connected by crank webs 16-23 extending in a direction crossing the axis Ax1. The crank pins 24-27 are connected to the distal ends of the crank webs 16-23, and their central axes are eccentric with respect to the axis Ax1. Counterweights 28-35 are integrally formed at the other ends of the crank webs 16-23.

In this specification, the crank journal 11 is the #1 crank journal, the crank journal 12 is the #2 crank journal, the crank journal 13 is the #3 crank journal, the crank journal 14 is the #4 crank journal, and the crank journal 15 is the #5 crank journal. It may be described as a crank journal.

The journal bearings 36 to 45 each have a semi-annular shape when viewed from the front along the axis Ax1. The journal bearings 36-45 are sliding bearings made of metal material. The journal bearings 36, 38, 40, 42, 44 are upper journal bearings arranged on the upper side of the engine, in other words, on the cylinder head side. On the other hand, the journal bearings 37, 39, 41, 43, 45 are lower journal bearings arranged on the lower side of the engine, in other words, on the oil pan side.

An upper journal bearing 36 and a lower journal bearing 37 are attached to the crank journal 11, an upper journal bearing 38 and a lower journal bearing 39 are attached to the crank journal 12, and an upper journal bearing 40 and a lower journal bearing 41 are attached. are mounted around the crank journal 13, an upper journal bearing 42 and a lower journal bearing 43 are mounted around the crank journal 14, and an upper journal bearing 44 and a lower journal bearing 45 are mounted around the crank journal 15. .

The journal bearings 36-45 are inserted between each of the plurality of bearing portions of the cylinder block (not shown) and each of the crank journals 11-15. Further, between the journal bearings 36-45 and the crank journals 11-15, the crankshaft 1 is rotatable around the axis Ax1, and a minute gap is formed in which an oil film is formed.

Furthermore, each of the upper journal bearings 36 , 38 , 40 , 42 , 44 has an oil hole connected to an oil gallery 46 . As a result, the oil from the oil gallery 46 is supplied between the journal bearings 36-45 and the crank journals 11-15 through the oil holes of the upper journal bearings 36, 38, 40, 42, 44.

The oil gallery 46 is an oil passage formed in a cylinder block (not shown). The oil gallery 46 is connected to an oil pump 47 for supplying oil from the oil pan to the oil gallery 46 . It should be noted that so-called low-viscosity oil is employed in the present embodiment. Specifically, in the SAE (Society of Automotive Engineers, Inc.) viscosity, oils with low-temperature viscosities of 0W-8 to 0W30 are employed.

2. Detailed Structure of Journal Bearings 36-45 The detailed structure of the journal bearings 36-45 will be described with reference to FIG.

In the crankshaft bearing structure 100 according to the present embodiment, the journal bearings 36, 37, 40, 41, 44, and 45 are mounted on the #1, #3, and #5 crank journals 11, 13, and 15, and # There are some structural differences between the journal bearings 38, 39, 42 and 43 that are ring-mounted on the crank journals 12 and 14 of #2 and #4. FIG. 2(a) shows journal bearings 36 and 37 as an example of journal bearings that are mounted on crank journals 11, 13 and 15 of #1, #3 and #5. Journal bearings 38 and 39 are shown as examples of the journal bearings that are ring-mounted on the #2 and #4 crank journals 12 and 14, respectively.

As shown in FIG. 2(a), each of the upper journal bearing 36 and the lower journal bearing 37 has a semi-annular shape when viewed from the front. The upper journal bearing 36 and the lower journal bearing 37 are mounted around the #1 crank journal 11 with their circumferential ends facing each other.

As described above, the upper journal bearing 36 is formed with the oil hole 36b in the vicinity of the top. As described with reference to FIG. 1, the oil gallery 46 is connected to the oil hole 36b of the upper journal bearing 36. As shown in FIG.

In the upper journal bearing 36 and the lower journal bearing 37, which are mounted on the #1 crank journal 11, grooves extending in the circumferential direction are not formed on the inner peripheral surfaces 36a and 37a, and the generatrix is a straight line parallel to the axis Ax1. The inner peripheral surfaces 36a and 37a are formed by the surfaces of revolution generated as .

As shown in FIG. 2(b), each of the upper journal bearing 36 and the lower journal bearing 37 mounted on the #2 crank journal 12 also has a semi-annular shape when viewed from the front. The upper journal bearing 38 is also formed with an oil hole 38b near the top. An oil gallery 46 is also connected to the oil hole 38b.

Of the upper journal bearing 38 and the lower journal bearing 39 that are mounted on the #2 crank journal 12, the lower journal bearing 39 does not have a circumferentially extending groove or the like formed on the inner peripheral surface 39a. An inner peripheral surface 39a is formed by a surface of revolution generated with parallel straight lines as generatrices.

On the other hand, a groove 38c extending in the circumferential direction is formed in the inner peripheral surface 38a of the upper journal bearing 38 in which the oil hole 38b is formed. The groove 38c is connected to the oil hole 38b and is formed from one circumferential end to the other circumferential end. The groove 38c formed in the inner peripheral surface 38a of the upper journal bearing 38 functions as a guide path for the oil supplied from the oil hole 38b and allows foreign particles to enter between the crank journal 12 and the journal bearings 38, 39. It also has the function of guiding the particulate foreign matter to the portion where the upper journal bearing 38 and the lower journal bearing 39 abut against each other.

3. Configuration of abutting portions of upper journal bearings 36, 38, 40, 42, 44 and lower journal bearings 37, 39, 41, 43, 45 Upper journal bearings 36, 38, 40, 42, 44 and lower journal bearings 37, 39 , 41, 43 and 45 will be described with reference to FIG. In addition, FIG. 3 shows, as an example, the abutting portion between the circumferential ends of the upper journal bearing 36 and the lower journal bearing 37 .

As shown in FIG. 3, the circumferential end surface of the upper journal bearing 36 is formed with a slope portion 36c. Specifically, the inclined surface portion 36c is formed of a plane oblique to the circumferential direction of the upper journal bearing 36 and extending along the axis Ax1 of the crankshaft 1 (see FIG. 1).

Similarly, the end face in the circumferential direction of the lower journal bearing 37 is also formed with a slope portion 37b. The slope portion 37b is also formed of a flat surface that is oblique to the circumferential direction of the lower journal bearing 37 and extends along the axis Ax1 of the crankshaft 1 (see FIG. 1).

As shown in FIG. 3, when the circumferential end portion of the upper journal bearing 36 and the circumferential end portion of the lower journal bearing 37 are butted against each other, the sloped portion 36c and the sloped portion 37b open toward the crank journal 11 side. Thus, a gap SP having a triangular cross section is formed. A gap SP formed between the slope portions 36c and 37b in this embodiment corresponds to a groove extending in a direction along the axial center Ax1 of the crankshaft 1. As shown in FIG.

4. Structure of Crank Journals 11, 13, 15 Among the crank journals 11 to 15, the structure of the crank journals 11, 13, 15 in which the journal bearings 36, 37, 40, 41, 44, 45 are mounted is shown in FIGS. Description will be made with reference to FIG. 4 and 5, only the crank journal 11 among the crank journals 11, 13 and 15 is shown as an example.

As shown in FIG. 4, the crank journal 11 is a cylindrical body centered on the axis Ax1 of the crankshaft 1. As shown in FIG. The crankshaft 1 rotates about the axis Ax1 in the direction of the arrow B1. Therefore, the crank journal 11 also rotates in the direction of the arrow B1.

On the outer peripheral surface 11a of the crank journal 11, two recesses 11b are formed on the circumference at positions opposed to each other in the radial direction of the crank journal 11 (only one recess 11b is shown in FIG. 4). As shown in FIG. 5, the recess 11b is formed to extend in a direction along the axis Ax1 of the crankshaft 1 when the outer peripheral surface 11a of the crank journal 11 is viewed from the outside in the radial direction. More specifically, the concave portion 11b is formed so that both end portions 11f and 11g are on the rear side in the rotational direction C of the crankshaft 1 with respect to the central portion 11e in the direction along the axis Ax1.

An end portion 11f of the concave portion 11b is arranged inside the side end 11c of the crank journal 11 in the direction along the axial center Ax1 of the crankshaft 1 with a space W1 therebetween. Similarly, the end 11g of the recess 11b is arranged inside the side end 11d of the crank journal 11 with a gap W2 in the direction along the axis Ax1 of the crankshaft 1 .

The outer peripheral surfaces 11a of the crank journals 11, 13, and 15, except for the portions where the recesses 11b are formed, are formed of rotational surfaces generated with a straight line parallel to the axis Ax1 as a generatrix. In other words, the outer peripheral surfaces 11a of the crank journals 11, 13, 15, excluding the portions where the recesses 11b are formed, are opposed to the inner peripheral surfaces 36a, 37a of the journal bearings 36, 37, 40, 41, 44, 45. It is composed of smooth arc curved surfaces (curved surfaces without circumferential grooves) facing each other with a minute gap between them.

5. Cross-sectional Shape of Recess 11b The cross-sectional shape of the recess 11b formed in the crank journals 11, 13, 15 will be described with reference to FIGS. 6 to 8. FIG. 6 to 8 show the concave portion 11b formed in the crank journal 11 as an example.

As shown in FIG. 6, the bottom surface 11h of the concave portion 11b has a substantially arc shape. Therefore, the radial depths D2 and D3 at the end portions 11f and 11g are shallower than the radial depth D1 at the central portion 11e. In addition, the bottom surface 11h is a smooth curved surface without steps.

As shown in FIG. 7, the central portion 11e (see FIG. 5) of the recess 11b has a radial depth D4 at a front portion 11i, which is a portion on the front side in the rotational direction E of the crankshaft 1, and a depth D4 at the rear side. is substantially the same as the radial depth D5 at the rear portion 11j.

On the other hand, as shown in FIG. 8, both ends 11f and 11g (see FIG. 5) of the recess are located at a depth D6 in the radial direction at the front portion 11k, which is the portion on the front side in the rotational direction F of the crankshaft 1. In contrast, the radial depth D7 at the rear portion 11l, which is the portion on the rear side, is shallow.

6. Ejection Mechanism of Granular Foreign Matter 500 Granular foreign matter (such as metal powder) 500 mixed with oil may enter between the crank journals 11, 13, 15 and the journal bearings 36, 37, 40, 41, 44, 45. . 9 and 10 are used to explain the mechanism for discharging the particulate foreign matter 500 that has entered between the crank journals 11, 13, 15 and the journal bearings 36, 37, 40, 41, 44, 45. to explain. 9 and 10 also show the crank journal 11 among the crank journals 11, 13 and 15 as an example.

It is assumed that a particulate foreign matter 500 mixed with oil enters between the crank journal 11 and the journal clamps 36 and 37 . In this case, as shown in FIG. 9(a), the granular foreign matter 500 that has entered with the rotation G1 of the crankshaft 1 is collected in the concave portion 11b. In the example shown in FIG. 9A, the granular foreign matter 500 is stuck in the front portion 11i of the central portion 11e (see FIG. 5) of the concave portion 11b (arrow H1).

As shown in FIG. 9(b), the particulate foreign matter 500 stuck in the concave portion 11b moves from the front portion 11i of the central portion 11e (see FIG. 5) due to the movement of the oil accompanying the rotation G2 of the crankshaft 1. Move to rear 11j (arrow H2). Then, the granular foreign matter 500 moves along the rear end of the recess 11b (the rear side in the rotation directions G3 and G4 of the crankshaft 1) due to the movement of the oil accompanying the rotations G3 and G4 of the crankshaft 1. Move to 11l behind 11g (arrows H3, H4).

As shown in FIG. 10(a), the granular foreign matter 500 moved to the rear portion 11l of the end portion 11g of the recess 11b is moved by the rotation I of the crankshaft 1 to the recess 11b and the gap SP (between the journal bearing 36 and the journal bearing 37). When the gap SP) formed between the sloped portions 36c and 37b at the abutting portion is connected, the oil is discharged into the gap SP together with the oil due to the centrifugal force. Then, as shown in FIG. 10(b), the particulate foreign matter 500 discharged into the clearance SP moves in the direction along the axial center Ax1 of the crankshaft 1 through the clearance SP (arrow J), and moves toward the crank journal. 11 and the journal bearings 36, 37 to the outside.

7. Effects In the crankshaft bearing structure 100 according to the present embodiment, the recesses 11b are provided in the outer peripheral surfaces 11a of the #1, #3, and #5 crank journals 11, 13, and 15. As shown in FIG. Therefore, even if the particulate matter 500 enters between the crank journals 11, 13, 15 and the journal bearings 36, 37, 40, 41, 44, 45, the rotation of the crankshaft 1 causes the particulate matter 500 to move into the recesses. 11b. The journal bearings 36, 37, 40, 41, 44, and 45 corresponding to the #1, #3, and #5 crank journals 11, 13, and 15 are provided with gaps SP at their abutting portions. This gap SP extends in a direction along the axis Ax1 of the crankshaft 1 and functions as a guide groove for discharging the foreign particle 500 to the outside. Therefore, the foreign particles 500 collected in the recessed portions 11b of the #1, #3, and #5 crank journals 11, 13, and 15 are removed from the recessed portions 11b by the gap SP and the gap SP as the oil moves as the crankshaft 1 rotates. discharged to the outside.

Further, in the crankshaft bearing structure 100, the inner peripheral surfaces of the journal bearings 36, 37, 40, 41, 44, and 45 that are ring-mounted on the #1, #3, and #5 crank journals 11, 13, and 15 are aligned with the crankshaft. It is composed of a surface of revolution generated with a straight line parallel to the axis (rotational axis) Ax1 of 1 as a generatrix. In other words, the crankshaft bearing structure 100 does not have circumferential grooves on the inner peripheral surfaces of the upper journal bearings 36, 40, 44 as in the prior art. In the crankshaft bearing structure 100 according to the present embodiment, grooves are formed in the upper journal bearings 36, 40, 44 in the circumferential direction by providing recesses 11b in parts of the outer peripheral surfaces 11a of the crank journals 11, 13, 15. Even if it does not have it, the intruding granular foreign matter 500 can be collected. Therefore, even if the circumferential grooves of the upper journal bearings 36, 40, 44 are eliminated, the foreign particles 500 that have entered can be discharged to the outside.

Further, in the crankshaft bearing structure 100, the concave portions 11b of the #1, #3, and #5 crank journals 11, 13, and 15 are formed in the shape of grooves extending along the axial center Ax1 of the crankshaft 1. As shown in FIG. Therefore, in the crankshaft bearing structure 100, it is possible to collect the intruded granular foreign matter 500 with a high probability in the concave portion 11b. In addition, it is possible to facilitate movement of the particulate foreign matter 500 collected in the recess 11b to the ends 11f and 11g of the recess 11b by the oil flow. Therefore, the particulate foreign matter 500 is more efficiently discharged to the outside through the gap SP formed between the butted portions of the journal bearings 36, 37, 40, 41, 44, and 45. FIG.

In the crankshaft bearing structure 100, both ends 11f and 11g of the concave portions 11b of the #1, #3 and #5 crank journals 11, 13 and 15 in the direction along the axis Ax1 of the crankshaft 1 11, 13 and 15 are arranged with intervals W1 and W2 from both side ends 11c and 11d. In other words, both end portions 11f and 11g of the crank journals 11, 13 and 15 are arranged inside the end portions 11c and 11d. Therefore, in the crankshaft bearing structure 100, the oil in the concave portions 11b of the #1, #3, #5 crank journals 11, 13, 15 is A decrease in hydraulic pressure due to leakage from 11c and 11d can be suppressed.

Further, in the crankshaft bearing structure 100, the concave portions 11b of the #1, #3, and #5 crank journals 11, 13, and 15 are located at both end portions 11f rather than the central portion 11e in the direction along the axis Ax1 of the crankshaft 1. , 11g are provided on the rear side in the direction of rotation of the crankshaft 1. As shown in FIG. Therefore, the particulate foreign matter 500 collected in the recess 11b moves to both ends 11f and 11g of the recess 11b due to the flow of oil accompanying the rotation of the crankshaft 1. As shown in FIG. Therefore, in the crankshaft bearing structure 100, the particulate foreign matter 500 that has entered between the #1, #3, #5 crank journals 11, 13, 15 and the journal bearings 36, 37, 40, 41, 44, 45 is removed to the outside. and can be discharged efficiently.

Further, in the crankshaft bearing structure 100, the bottom surface 11h is formed such that the radial depths D2 and D3 at both ends 11f and 11g of the recess 11b are shallower than the radial depth D1 at the central portion 11e. there is Therefore, the foreign particles 500 collected in the recessed portion 11b move toward the both ends 11f, 11g of the recessed portion 11b due to the flow of oil accompanying the rotation of the crankshaft 1, and move toward the journal bearings 36, 37, 49. , 41, 44, and 45 toward the outside in the radial direction (ends 11f and 11g). Therefore, in the crankshaft bearing structure 100, when the recess 11b and the gap SP between the journal bearings 36, 37, 40, 41, 44, and 45 are connected by the rotation of the crankshaft 1, the particulate foreign matter 500 is discharged into the gap SP. easy to do

Further, in the crankshaft bearing structure 100, the bottom surface 11h is formed such that the depth D7 of the rear portion 11l is shallower than the depth D6 of the front portion 11k at both end portions 11f and 11g of the recess portion 11b. formed. For this reason, in the crankshaft bearing structure 100, the granular foreign matter 500 collected in the concave portion 11b moves toward the rear portion 11l of the both end portions 11f and 11g due to the flow of oil accompanying the rotation of the crankshaft 1, and the journal bearing 11b moves toward the rear portion 11l. Move radially outward to approach 36, 37, 40, 41, 44, 45. Therefore, in the crankshaft bearing structure 100, when the recess 11b and the gap SP between the journal bearings 36, 37, 40, 41, 44, and 45 are connected by the rotation of the crankshaft 1, the particulate foreign matter 500 is discharged into the gap SP. easy to do

Further, in the crankshaft bearing structure 100, the journal bearings are configured by combinations of upper journal bearings 36, 38, 40, 42, 44 and lower journal bearings 37, 39, 41, 43, 45 each having a semi-annular shape. The crank journals 11 to 15 are mounted in a circular manner by , and a gap SP formed at the butted portion constitutes a guide groove for discharging the particulate foreign matter 500 . Therefore, in the crankshaft bearing structure 100, journal bearings (upper journal bearings 36, 38, 40, 42, 44 and lower journal bearings 37, 39, 41, 43, 45) for the crank journals 11 to 15 are combined. journal bearing) can be easily installed. Further, in the crankshaft bearing structure 100, the inner peripheral surfaces 36a, 37a, 38a, 39a of the upper journal bearings 36, 38, 40, 42, 44 and the lower journal bearings 37, 39, 41, 43, 45 are subjected to cutting or the like. It is possible to discharge the particulate foreign matter 500 to the outside through the gap SP of the abutted portion without performing a separate machining.

Further, in the crankshaft bearing structure 100, the concave portions 11b of the #1, #3, and #5 crank journals 11, 13, and 15 are provided at two positions on the circumference. Therefore, in the crankshaft bearing structure 100, it is possible to collect the particulate foreign matter 500 with high efficiency compared to the case where the concave portion 11b is provided only at one place on the circumference. It should be noted that if the concave portions 11b are provided at three or more locations on the circumference, it is excellent from the viewpoint of collecting the particulate foreign matter 500, but this causes a decrease in the rigidity of the crankshaft 1, which is not preferable.

As described above, in the crankshaft bearing structure 100 according to the present embodiment, even if the upper journal bearings 36, 38, 40, 42, 44 are not provided with grooves extending in the circumferential direction ), the foreign particles 500 can be discharged from between the journal bearings 36, 37, 40, 41, 44, 45 and the #1, #3, #5 crank journals 11, 13, 15, Even when low-viscosity oil is used, it is possible to secure an appropriate hydraulic pressure while suppressing an increase in the load on the oil pump 47 .

[Modification 1]
A crankshaft bearing structure according to Modification 1 will be described with reference to FIG. FIG. 11(a) shows only some crank journals 48 among the plurality of crank journals. The crankshaft bearing structure according to this modification has the same configuration as the crankshaft bearing structure 100 according to the above-described embodiment, except for the shape of the recessed portion 48b of the crank journal 48 in plan view, which will be described with reference to FIG. 11(a). .

As shown in FIG. 11(a), in the crank journal 48 according to this modified example, the concave portion 48b formed in the outer peripheral surface 48a has a substantially circular shape in plan view. In other words, the concave portion 48b is formed in a dot shape in plan view. The shape of the concave portion 48a in a plan view does not have to be a perfect circle, and may be a polygonal shape or a shape that expands in a direction intersecting the rotation direction K1 of the crankshaft.

The crankshaft bearing structure according to this modified example can also obtain the same effect as the crankshaft bearing structure 100 according to the above-described embodiment.

[Modification 2]
A crankshaft bearing structure according to Modification 2 will be described with reference to FIG. 11(b). FIG. 11(b) also shows only some of the crank journals 49 among the plurality of crank journals. The crankshaft bearing structure according to this modification has the same configuration as the crankshaft bearing structure 100 according to the above-described embodiment, except for the shape of the concave portion 49b of the crank journal 49 in plan view, which will be described with reference to FIG. 11(b). .

As shown in FIG. 11(b), in the crank journal 49 according to this modification, the recess 49b formed in the outer peripheral surface 49a has a shape in plan view that is larger than the length in the rotation direction K2 of the crankshaft. It has an oval shape with a wide width in the direction perpendicular to the direction K2.

The crankshaft bearing structure according to this modified example can also obtain the same effect as the crankshaft bearing structure 100 according to the above-described embodiment.

[Modification 3]
A crankshaft bearing structure according to Modification 3 will be described with reference to FIG. 11(c). FIG. 11(c) also shows only some of the crank journals 50 among the plurality of crank journals. The crankshaft bearing structure according to this modification has the same configuration as the crankshaft bearing structure 100 according to the above-described embodiment, except for the shape of the recessed portion 50b of the crank journal 50 in plan view, which will be described with reference to FIG. 11(c). .

As shown in FIG. 11(c), in the crank journal 50 according to this modification, the front side 50c in the rotational direction K3 of the crankshaft is arcuate in plan view, and the rear side 50d is V-shaped in plan view. ing. In the crank journal 50 according to the present modification as well, after the particulate foreign matter that has entered is collected in the recessed portion 50b, the particulate foreign matter is moved to the rear portion of both ends of the recessed portion 50b by the flow of oil accompanying the rotation of the crankshaft. .

The crankshaft bearing structure according to this modified example can also obtain the same effect as the crankshaft bearing structure 100 according to the above-described embodiment.

[Modification 4]
A crankshaft bearing structure according to Modification 4 will be described with reference to FIG. 12 . FIG. 12 also shows only some crank journals 51 of the plurality of crank journals. The crankshaft bearing structure according to this modification has the same configuration as the crankshaft bearing structure 100 according to the above-described embodiment, except for the cross-sectional shape of the recessed portion 51b of the crank journal 51, which will be described with reference to FIG.

As shown in FIG. 12, in the recessed portion 51b of the crank journal 51 according to this modification, the depth in the radial direction is gradually greater at both end portions 51f and 51g than at the central portion 51e in the direction along the axial center of the crankshaft. The bottom surface 51h is formed in a V shape so as to be shallow. Even in the crank journal 51 having the recess 51b with the bottom surface 51h formed in a V-shape, the foreign particles collected in the recess 51 are moved to the opposite ends 51f and 51g by the oil flow. By moving toward both end portions 51f and 51g, the particulate foreign matter moves toward the outer peripheral surface 51a of the crank journal 51 and is easily discharged into the groove of the journal bearing.

The crankshaft bearing structure according to this modified example can also obtain the same effect as the crankshaft bearing structure 100 according to the above-described embodiment.

[Other Modifications]
In the above embodiment, a four-cylinder engine is used as an example, and the crankshaft 1 is provided with five crank journals 11 to 15, but the present invention is not limited to this. For example, it is possible to employ a two-cylinder, three-cylinder, or five-cylinder or more engine.

Further, in the above embodiment, among the #1 to #5 crank journals 11 to 15, the #1, #3, and #5 crank journals 11, 13, and 15 are provided with the recesses 11b on the outer peripheral surfaces 11a. The invention is not limited to this. For example, one or two crank journals may be recessed, or all crank journals may be recessed.

Further, in the above embodiment, the recesses 11b are provided at two radially opposed locations in each of the #1, #3, and #5 crank journals 11, 13, and 15, but the present invention is not limited to this. does not receive For example, one recess may be provided on the circumference, or three or more recesses may be provided on the circumference.

Further, in the above embodiment and Modification 4, the bottom surfaces 11h, 51h of the recesses 11b, 51b are curved or slanted, and the center portions 11e, 51e and the ends 11f, 11g, 51f, 51g form the recesses 11b. , 51b and the front and rear portions 11k and 11l of the ends 11f and 11g, respectively, but the present invention is not limited to this. . For example, the depth of the recess can be made uniform.

Further, in the above embodiment, the journal bearings that are ring-mounted to the crank journals 11 to 15 are the upper journal bearings 36, 38, 40, 42, 44 and the lower journal bearings 37, 39, 41, 43, 45. Although configured by a combination, the present invention is not limited to this. For locations where there is no problem in assembling, it is possible to adopt an integrally structured journal bearing having an annular shape, or to combine three or more journal bearings.

In the above embodiment, the journal bearings 36, 37, 40, 41, 44, and 45 that are ring-mounted on the #1, #3, and #5 crank journals 11, 13, and 15 have inner peripheral surfaces 36a and 37a. An upper journal mounted on the #2 and #4 crank journals 12 and 14 using a member composed of a rotating surface having no circumferential groove (a rotating surface generated with a straight line parallel to the axis Ax1 as a generatrix) Although the bearings 38 and 42 have grooves 38c formed in the inner peripheral surface 38a in the circumferential direction, the present invention is not limited to this. For example, the inner peripheral surfaces of the journal bearings that are ring-mounted on all crank journals may be configured with a rotating surface (a rotating surface generated with a straight line parallel to the axis Ax1 as a generatrix) having no grooves in the circumferential direction. is also possible.

Further, in the above-described embodiment, the gaps SP formed at the abutting portions of the upper journal bearings 36, 38, 40, 42, 44 and the lower journal bearings 37, 39, 41, 43, 45 are used as guides for discharging the particulate foreign matter 500. Although grooves are used, the present invention is not limited to this. For example, one or more grooves extending along the axial center of the crankshaft may be formed in a journal bearing that is attached to the crank journal.

In the above embodiment and Modifications 1 to 4, no particular reference was made to the sizes of the recesses 11b, 48b, 49b, 50b, 51b formed in the #1, 3, 5 crank journals 11, 13, 15. It can be set within a range that does not adversely affect the formation of an oil film between the journal and the journal bearing. For example, the outer peripheral surfaces of the #2 and #4 crank journals 12 and 14 are provided with openings for the shaft internal oil passages for supplying oil to the adjacent crank pins 24-27. The lengths of the recesses 11b, 48b, 49b, 50b, and 51b in can be made equal to the diameters of the openings provided on the outer peripheral surfaces of the #2 and #4 crank journals 12 and 14, respectively. This is advantageous in achieving both the discharge of foreign matter and the formation of an oil film.

1 Crankshaft 11-15, 48-51 Crank journal 11a, 48a, 49a, 50a, 51a Outer peripheral surface 11b, 48b, 49b, 50b, 51b Concave portion 36, 38, 40, 42, 44 Upper journal bearing 36a, 38a Inner circumference Surfaces 36b, 38b Oil holes 37, 39, 41, 43, 45 Lower journal bearing 46 Oil gallery (oil passage)
100 Crankshaft bearing structure 500 Particulate foreign matter

Claims (7)

a crankshaft extending along a predetermined direction and having a plurality of crank journals spaced apart from each other in the predetermined direction;
a cylinder block having a plurality of bearings disposed so as to surround radially outer sides of the plurality of crank journals and rotatably supporting the crankshaft;
a journal bearing mounted on each of the plurality of crank journals between each of the plurality of crank journals and each of the plurality of bearing portions in a state in which the crankshaft is rotatable;
with
The cylinder block further has an oil passage,
At least some crank journals among the plurality of crank journals are provided so as to be recessed radially inward from an outer peripheral surface along the inner peripheral surface of the journal bearing in a part of the crank journal in the circumferential direction, Having dot-shaped or groove-shaped recesses extending in the predetermined direction in plan view from the radially outer side,
The journal bearing, which is annularly attached to at least a part of the crank journal, is connected to the oil passage at an upper portion thereof, and supplies oil from the oil passage to a space between the journal bearing and the crank journal. a hole, an inner peripheral surface that is a rotation surface generated with a straight line parallel to the rotation axis of the crankshaft as a generatrix, and a groove extending in the predetermined direction on the inner peripheral surface,
Crankshaft bearing structure. A crankshaft bearing structure according to claim 1, wherein
The concave portion of the at least one portion of the crank journal is a groove-shaped concave portion extending in the predetermined direction, and both ends of the concave portion are located inside the both side ends of the at least the portion of the crank journal in the predetermined direction. is located in the
Crankshaft bearing structure. A crankshaft bearing structure according to claim 2, wherein
Both ends of the recess are arranged to be rearward in the rotational direction of the crankshaft relative to the central portion of the recess.
Crankshaft bearing structure. In the crankshaft bearing structure according to claim 2 or 3,
The bottom surface of the concave portion is formed such that the radial depth at the both ends is shallower than the central portion.
Crankshaft bearing structure. In the crankshaft bearing structure according to any one of claims 2 to 4,
The bottom surface of the recess is formed such that the radial depth on the rear side in the rotational direction is shallower than on the front side at both ends.
Crankshaft bearing structure. In the crankshaft bearing structure according to any one of claims 1 to 5,
The journal bearing comprises an upper journal bearing and a lower journal bearing each having a semi-annular shape in a front view from the predetermined direction,
Each of the upper journal bearing and the lower journal bearing has a circumferential end surface that is oblique to the circumferential direction of the journal bearing and has a slope portion that extends along the predetermined direction,
The groove in the journal bearing is formed by a gap between the inclined surfaces formed when the circumferential end of the upper journal bearing and the circumferential end of the lower journal bearing are butted against each other. ,
Crankshaft bearing structure. A crankshaft bearing structure according to claim 6, wherein
The recessed portions of the at least a portion of the crank journal are provided at two locations on the circumference so as to face each other in the radial direction.
Crankshaft bearing structure.

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