JP2023038980A - Crank shaft bearing structure - Google Patents

Abstract

To provide a crank shaft bearing structure capable of reducing an amount of oil leakage from a part between a crank journal and a journal bearing at both ends of a shaft, even in being applied to an engine with an odd number of cylinders.SOLUTION: A crank shaft bearing structure 100 is applied to a five-cylinder engine. A crank shaft 1 extends in a direction along a shaft center Ax1 and has six crank journals 11-16 and five crank pins 27-31. The crank journals 12, 13, 15 are connected to in-shaft oil passages 56-62 for supplying oil to the crank pins 27-31 respectively adjacent thereto. A journal bearing having a peripheral groove extending in a circumferential direction and connected to an oil hole on an inner peripheral surface is annularly mounted on the crank journals 12, 13, 15, and a journal bearing not having a peripheral groove on an inner peripheral surface is annularly mounted on the crank journals 11, 14, 16.SELECTED DRAWING: Figure 2

Description

TECHNICAL FIELD The present invention relates to a crankshaft bearing structure, and more particularly to a crankshaft bearing structure applied to an odd-numbered cylinder engine.

A vehicle engine includes a crankshaft that outputs rotational driving force. The crankshaft is supported by bearings in the cylinder block. A journal bearing is interposed between the bearing portion of the cylinder block and the crank journal of the crankshaft.

In Patent Document 1, when viewed from the front in the axial direction of the crankshaft, a journal bearing is configured by combining with a journal bearing, each of which has a semi-annular shape. A circumferential groove extending in the circumferential direction is formed in the inner peripheral surface so as to be continuous with the oil hole serving as an oil supply port from the oil inlet. In the structure disclosed in Patent Document 1, oil supplied from an oil gallery is guided to a lower journal bearing using a circumferential groove as a guide path. In addition, the circumferential groove provided on the inner peripheral surface of the upper journal bearing also functions as a guide path for discharging particulate foreign matter such as metal powder from between the crank journal and the journal bearing to the outside.

Also, the crankshaft has a crank pin formed between crank journals. The crankpin is a part that is rotatably connected to a connecting rod that is connected to the piston. A connecting rod bearing is interposed between the connecting rod and the crankpin, and as a supply path for lubricating the connecting rod bearing, an in-shaft oil passage is provided that connects the adjacent crank journal to the crankpin. A part of the oil supplied between the crank journal and the journal bearing is supplied to the crankpin through the in-shaft oil passage.

JP 2015-34572 A

A vehicle may be equipped with an in-line, odd-numbered cylinder engine. In an engine with an odd number of cylinders in series, a couple of forces is generated at both ends of the crankshaft as the engine is driven. For example, a crankshaft 9 of an in-line five-cylinder engine shown in FIG. 8 has six crank journals 901 to 906 and five crank pins 907 to 911, and rotates around an axis Ax9 when driven by the engine. When the engine is driven, forces act on the crankpins 907 to 911 in a predetermined order along with combustion in the combustion chamber. In this case, in an odd-numbered cylinder engine, the load applied to the crankshaft due to the combustion pressure is unbalanced. , F2 are generated.

Therefore, when applying the conventional crankshaft bearing structure to an odd-numbered cylinder engine, there is room for improvement in terms of the amount of oil leaked from between the journal bearings and the crank journals located at both ends of the crankshaft. rice field. That is, as shown in FIG. 8, when the couple of forces F1 and F2 is generated at both ends of the crankshaft, the runout at both ends of the crankshaft increases. more oil leaks from As a result, the lubrication between the crank journal and the journal bearing at both ends of the shaft becomes insufficient, which poses a problem in terms of reliability of the engine. In addition, the amount of oil leaking from between the crank journal and the journal bearing at both ends of the shaft increases, increasing the load on the oil pump. As a result, there is concern about deterioration in fuel consumption. Thus, in an odd-numbered cylinder engine, it is necessary to reduce the amount of oil leakage at both ends of the shaft as described above, improve engine reliability, and improve fuel efficiency by reducing the load on the oil pump. Become.

In recent years, in particular, low-viscosity oil has been used for the purpose of improving engine fuel efficiency. When force is generated, the amount of oil leaking from between the crank journals at both ends of the shaft and the journal bearings increases.

The present invention is intended to solve the above-mentioned problems, and even when applied to an odd-numbered cylinder engine, the amount of oil leaked from between the crank journal and the journal bearing at both ends of the shaft is It is an object of the present invention to provide a crankshaft bearing structure capable of reducing the

A crankshaft bearing structure according to one aspect of the present invention is applied to an odd-numbered cylinder engine. A crankshaft bearing structure according to this aspect includes a crankshaft, a cylinder block, and a plurality of journal bearings. The crankshaft extends in a predetermined direction and has a plurality of crank journals. The plurality of crank journals are spaced apart from each other in the predetermined direction.

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

In the crankshaft bearing structure according to this aspect, the cylinder block has an oil passage. Also, the plurality of journal bearings includes a first journal bearing and a second journal bearing. A said 1st journal bearing is ring-mounted by some crank journals of these journal bearings. The second journal bearing is mounted around other crank journals of the plurality of journal bearings except for the part of the crank journals.

The first journal bearing has an oil hole and a circumferential groove. The oil hole is connected to the oil passage at an upper portion, and supplies oil from the oil passage between the journal bearing and the crank journal. The circumferential groove is a circumferentially extending groove connected to the oil hole on the inner circumferential surface of the journal bearing.

The second journal bearing has an inner peripheral surface and an oil hole. The inner peripheral surface is configured by a surface of revolution generated with a straight line parallel to the predetermined direction as a generatrix. The oil hole is connected to the oil passage at an upper portion, and supplies oil from the oil passage to a space between the inner peripheral surface and the crankshaft.

In the crankshaft bearing structure according to this aspect, the second journal bearing is attached to at least one of the plurality of crank journals located at both ends in the predetermined direction.

In the crankshaft bearing structure according to the above aspect, the inner peripheral surfaces of the crank journals located at both ends of the crankshaft in the predetermined direction are formed of the rotating surfaces (the inner peripheral surfaces do not have circumferential grooves). ) The second journal bearing is encircled. Therefore, in an odd-numbered cylinder engine, it is possible to reduce the amount of oil leaking from between the crank journal and the inner peripheral surface of the second journal bearing at both ends even when a couple of forces is generated in the crankshaft. . Even if low-viscosity oil is used and the temperature of the low-viscosity oil is high, the amount of oil leaked from between the crank journals at both ends of the crankshaft and the second journal bearing can be reduced. can. Therefore, in the crankshaft bearing structure according to the above aspect, even if a couple of forces is generated at both ends of the crankshaft, the amount of oil leakage due to vibration of the both ends is reduced, so that the crank journals at both ends and the second journal It is possible to maintain high reliability of the engine by maintaining lubrication between the bearings, and to improve fuel efficiency by suppressing an increase in the load on the oil pump.

On the other hand, in the crankshaft bearing structure according to the aspect described above, the first journal bearing having the circumferential groove on the inner peripheral surface is mounted on some of the plurality of crank journals. , a relatively large amount of oil is supplied between the part of the crank journal and the first journal bearing. Also, since the first journal bearing has a circumferential groove, even if particulate foreign matter such as metal powder enters between the crank journal and the first journal bearing, the particulate foreign matter is discharged to the outside together with the oil through the circumferential groove. is superior to

In the crankshaft bearing structure according to the aspect described above, each of the plurality of journal bearings may be composed of an upper journal bearing and a lower journal bearing each having a semi-annular shape in a front view from the predetermined direction. , The circumferential groove in the first journal bearing may be provided only in the upper journal bearing.

In the crankshaft bearing structure according to the above aspect, since the inner peripheral surface of the upper journal bearing is provided with the circumferential groove, the oil supplied through the oil hole of the upper journal bearing is guided toward the lower journal bearing.

On the other hand, since the lower journal bearing does not have a circumferential groove, it is superior in ensuring proper oil pressure between the lower journal bearing and the crank journal.

In the crankshaft bearing structure according to the aspect described above, the crankshaft includes a crankpin disposed between the adjacent crank journals in the predetermined direction, and the partial crank journal on which the first journal bearing is mounted. It may further have an in-shaft oil passage that extends from the chisel and guides oil to the crank pin adjacent to the crank journal.

In the crankshaft bearing structure according to the above aspect, the shaft internal oil passage is formed in the part of the crank journal, and a part of the oil supplied between the first journal bearing and the crank journal flows into the crank pin. supplied to Even in this case, since the first journal bearing is provided with a circumferential groove and a relatively large amount of oil is supplied between the first journal bearing and the crank journal, a portion of the oil flows to the crank pin. , it is possible to ensure an appropriate hydraulic pressure between the first journal bearing and the crank journal.

In the crankshaft bearing structure according to each aspect described above, even when applied to an odd-numbered cylinder engine, it is possible to reduce the amount of oil leaked from between the crank journal and the journal bearing at both ends of the shaft.

1 is a schematic diagram showing a crankshaft bearing structure according to a first embodiment; FIG. FIG. 4 is a cross-sectional view showing the structure of an in-shaft oil passage in a crankshaft; (a) is a perspective view showing the structure of an upper and lower journal bearing mounted on a #1 crank journal, and (b) is a perspective view showing the structure of an upper journal bearing therein. (a) is a perspective view showing the structure of an upper and lower journal bearing mounted on a #2 crank journal, and (b) is a perspective view showing the structure of an upper journal bearing therein. (a) is a sectional view showing a #1 crank journal and an upper journal bearing, and (b) is a sectional view showing a #2 crank journal and an upper journal bearing. It is a schematic diagram which shows the crankshaft bearing structure which concerns on 2nd Embodiment. FIG. 4 is a cross-sectional view showing the structure of an in-shaft oil passage in a crankshaft; FIG. 4 is a schematic diagram for explaining a couple of forces generated on a crankshaft in an odd-numbered cylinder engine;

EMBODIMENT OF THE INVENTION Below, embodiment of this invention is described, considering drawing into consideration. It should be noted that the embodiments described below are intended to exemplify the present invention, and the present invention is not limited to the following embodiments except for its essential configuration.

[First embodiment]
1. Schematic Configuration of Crankshaft Bearing Structure 100 A schematic configuration of a crankshaft bearing structure 100 according to a first embodiment of the present invention will be described with reference to FIG. Note that illustration of a cylinder block and the like is omitted in the figure. Therefore, the illustration of the shaft support formed on the cylinder block is also omitted. 1 also omits illustration of a connecting rod, a connecting rod bearing, and the like, which are connected to the crankshaft 1. As shown in FIG.

The crankshaft bearing structure 100 is applied to a 5-cylinder (odd-numbered) engine. As shown in FIG. 1, the crankshaft bearing structure 100 includes a crankshaft 1, a cylinder block (not shown), and a plurality of journal bearings 42-53. The crankshaft bearing structure 100 also includes an oil gallery (oil passage) 54 formed in a cylinder block (not shown) and an oil pump 55 for sending oil to the oil gallery 54 .

Crankshaft 1 extends along axis Ax1. In the present embodiment, the direction in which the axis Ax1 extends 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 16 spaced apart from each other in the direction along the axis Ax1. The crankshaft 1 also has crank pins 27-31 arranged between adjacent crank journals 11-16 in the direction along the axis Ax1.

In the crankshaft 1, the crank journals 11-16 and the crank pins 27-31 adjacent in the direction along the axis Ax1 are connected by crank webs 17-26 extending in the direction intersecting the axis Ax1. The crankpins 27-31 are connected to the distal ends of the crank webs 17-26, and their central axes are eccentric with respect to the axis Ax1. Counterweights 32-41 are integrally formed with the crank webs 17-26 at the other ends of the crank webs 17-26.

In this embodiment, 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. The journal and crank journal 16 may be referred to as #6 crank journal.

The journal bearings 42-53 are interposed between the bearings (not shown) of the cylinder block and the crank journals 11-16. Each of the journal bearings 42 to 53 has a semi-annular shape when viewed from the front along the axis Ax1 of the crankshaft 1 . The journal bearings 42-53 are sliding bearings made of metal material. Incidentally, the journal bearings 42, 44, 46, 48, 50, 52 are arranged on the upper side (fourth adjacent head side) with respect to the crank journals 11-16, and cover the upper half circumference of the crank journals 11-16. journal bearing". On the other hand, the journal bearings 43, 45, 47, 49, 51, 53 are arranged on the lower side (oil pan side) of the crank journals 11-16 and cover the lower half of the crank journals 11-16. lower journal bearing".

An upper journal bearing 42 and a lower journal bearing 43 are attached to the #1 crank journal 11. An upper journal bearing 44 and a lower journal bearing 45 are attached to the #2 crank journal 12. An upper journal bearing 46 and a lower journal bearing 45 are attached to the #2 crank journal 12. The journal bearing 47 is attached to the #3 crank journal 13, the upper journal bearing 48 and the lower journal bearing 49 are attached to the #4 crank journal 14, and the upper journal bearing 50 and the lower journal bearing 51 are attached to the #4 crank journal 14. The #5 crank journal 15 is ring-mounted, and the #6 crank journal 16 is ring-mounted with the upper journal bearing 52 and the lower journal bearing 53 . Although the details will be described later, the crank journals 12, 13 and 15 correspond to "partial crank journals" and the journal bearings 44 to 47, 50 and 51 correspond to "first journal bearings". Further, the crank journals 11, 14, 16 correspond to "other crank journals", and the journal bearings 42, 43, 48, 49, 52, 53 correspond to "second journal bearings".

Between the journal bearings 42-53 and the crank journals 11-16, the crankshaft 1 is rotatable around the axis Ax1, and a fine gap is formed in which an oil film is formed. Each of the upper journal bearings 42 , 44 , 46 , 48 , 50 , 52 has an oil hole connected to an oil gallery 54 as an oil supply port for forming this oil film. That is, in the crankshaft bearing structure 100 according to this embodiment, the oil flows between the journal bearings 42-53 and the crank journals 11-16 through the oil holes of all the upper journal bearings 42, 44, 46, 48, 50, 52. is supplied.

The oil gallery 54 is an oil passage formed in a cylinder block (not shown). An oil pump 55 is connected to the oil gallery 54 to supply the oil stored in the oil pan to the oil gallery 54 . In this embodiment, so-called low-viscosity oil is used as the oil. Specifically, oils with SAE (Society of Automotive Engineers, Inc.) viscosities of 0W-8 to 0W-30 are employed.

2. Shaft internal oil passages 56 to 62 of crankshaft 1
The crankshaft 1 of the crankshaft bearing structure 100 according to the present embodiment has in-shaft oil passages 56 to 62 that are formed in the shaft and serve as flow passages for oil. The in-shaft oil passages 56 to 62 provided in the crankshaft 1 will be described with reference to FIG.

As shown in FIG. 2, in the crankshaft 1, the outer peripheral surfaces 11a, 14a and 16a of the #1, #4 and #6 crank journals 11, 14 and 16 are not provided with openings. On the other hand, openings 12b, 13b and 15b are provided in the outer peripheral surfaces 12a, 13a and 15a of the #2, #3 and #5 crank journals 12, 13 and 15, respectively. The opening 12b is an inlet through which oil enters the in-shaft oil passage 56 . The opening 13 b is an inlet through which oil enters the in-shaft oil passage 59 . The opening 15 b is an inlet through which oil enters the in-shaft oil passage 60 .

The in-shaft oil passage 56 is formed to extend from the outer peripheral surface 12 a of the crank journal 12 in a direction perpendicular to the axial center Ax 1 of the crankshaft 1 . Inside the crankshaft 1 , two in-shaft oil passages 57 and 58 are connected to the in-shaft oil passage 56 . The two in-shaft oil passages 57 and 58 are formed to extend obliquely with respect to the axial center Ax<b>1 of the crankshaft 1 .

The in-shaft oil passage 57 is formed with an opening 27b provided in the outer peripheral surface 27a of the crankpin 27 as a terminal. The in-shaft oil passage 58 is formed terminating at an opening 28b provided in the outer peripheral surface 28a of the crankpin 28 . In the crankshaft bearing structure 100 according to the present embodiment, no shaft internal oil passage is formed from the outer peripheral surface 27a of the crankpin 27 in the crankshaft 1 toward the crank journal 11. No shaft internal oil passage is formed from the surface 28a toward the crank journal 13. As shown in FIG.

The in-shaft oil passage 59 extends from the outer peripheral surface 13a of the crank journal 13 in a direction perpendicular to the axial center Ax1 of the crankshaft 1, changes course in an oblique direction inside the crankshaft 1, and terminates at an opening 29b of the crankpin 29. is formed as In addition, in the crankshaft bearing structure 100 according to the present embodiment, an in-shaft oil passage from the outer peripheral surface 29a of the crankpin 29 of the crankshaft 1 toward the crank journal 14 is not formed.

The in-shaft oil passage 60 is formed to extend from the outer peripheral surface 15 a of the crank journal 15 in a direction orthogonal to the axial center Ax 1 of the crankshaft 1 . Inside the crankshaft 1 , two in-shaft oil passages 61 and 62 are connected to the in-shaft oil passage 60 . The two in-shaft oil passages 61 and 62 are also formed to extend obliquely with respect to the axis Ax1 of the crankshaft 1 .

The in-shaft oil passage 61 is formed terminating at an opening 30b provided in the outer peripheral surface 30a of the crankpin 30 . The in-shaft oil passage 61 is formed with an opening 31b provided in the outer peripheral surface 31a of the crankpin 31 as a terminal. In the crankshaft bearing structure 100 according to the present embodiment, no shaft internal oil passage is formed from the outer peripheral surface 30a of the crankpin 30 in the crankshaft 1 toward the crank journal 14, and the outer circumference of the crankpin 31 is not formed. An internal shaft oil passage from the surface 31a toward the crank journal 16 is not formed.

A portion of the oil supplied from the oil gallery 54 to between the journal bearings 44, 45 and the #2 crank journal 12 is introduced into the in-shaft oil passage 56 as indicated by arrow B1. The oil introduced into the shaft internal oil passage 56 is distributed to the shaft internal oil passage 57 and the shaft internal oil passage 58 connected to the shaft internal oil passage 56 inside the crankshaft 1 . As indicated by arrows B2 and B3, oil flows from the shaft internal oil passages 57 and 58 through the openings 27b and 28b of the crankpins 27 and 28 and between the crankpins 27 and 28 and connecting rod bearings (not shown). supplied.

In the crankshaft bearing structure 100 according to the present embodiment, no shaft internal oil passage is formed between the outer peripheral surface 27a of the crankpin 27 and the outer peripheral surface 11a of the #1 crank journal 11. 1 rotates as indicated by arrow A, the oil supplied between the journal bearings 42, 43 and the #1 crank journal 11 is not drawn to the crank pin 27.

A part of the oil supplied between the journal bearings 46, 47 and the #3 crank journal 13 from the oil gallery 54 is introduced into the in-shaft oil passage 59 as indicated by an arrow B4. The oil introduced into the in-shaft oil passage 59 passes through the opening 29b of the crankpin 29 and is supplied between the crankpin 29 and a connecting rod bearing (not shown), as indicated by an arrow B5.

In the crankshaft bearing structure 100 according to the present embodiment, similarly to the above, no shaft internal oil passage is formed between the outer peripheral surface 29a of the crankpin 29 and the outer peripheral surface 14a of the #4 crank journal 14. Therefore, even if the crankshaft 1 rotates as indicated by the arrow A, the oil supplied between the journal bearings 48, 49 and the #4 crank journal 14 will not be drawn to the crank pin 29. .

A part of the oil supplied from the oil gallery 54 to between the journal bearings 50, 51 and the #5 crank journal 15 is introduced into the in-shaft oil passage 60 as indicated by arrow B6. The oil introduced into the in-shaft oil passage 60 is distributed to the in-shaft oil passage 61 and the in-shaft oil passage 62 connected to the in-shaft oil passage 60 inside the crankshaft 1 . As indicated by arrows B7 and B8, oil flows from the shaft internal oil passages 61 and 62 through the openings 30b and 31b of the crankpins 30 and 31 and between the crankpins 30 and 31 and connecting rod bearings (not shown). supplied.

In addition, in the crankshaft bearing structure 100 according to the present embodiment, similarly to the above, there is a gap between the outer peripheral surface 31a of the crankpin 31 and the outer peripheral surface 16a of the #6 crank journal 16, and between the outer peripheral surface 30a of the crankpin 30 and the #4 crankpin 30. Since no shaft internal oil passage is formed between the crank journal 14 and the outer peripheral surface 14a, even if the crankshaft 1 rotates as indicated by the arrow A, the journal bearings 48, 49, 51, Oil supplied between 53 and #4, #6 crank journals 14, 16 is not drawn to crank pins 30, 31.

3. Detailed Structure of Journal Bearings 42-53 The detailed structure of the journal bearings 42-53 will be described with reference to FIGS. 3 and 4. FIG.

In the crankshaft bearing structure 100 according to this embodiment, journal bearings 44, 45, 46, 47, 50, 51 are mounted on #2, #3, #5 crank journals 12, 13, 15, and #1, There are some structural differences between the journal bearings 42, 43, 48, 49, 52, and 53 that are ring-mounted on the #4 and #6 crank journals 11, 14, and 16, respectively. 3(a) and 3(b) show examples of journal bearings 44, 45, 46, 47, 50, 51 mounted on the #2, #3, #5 crank journals 12, 13, 15. 42, 43 are illustrated, and FIGS. 4(a) and 4(b) show journal bearings 42, 43, 48, 49, 52 which are mounted on #1, #4, #6 crank journals 11, 14, 16. , 53 are illustrated as journal bearings 44 and 45 .

As shown in FIG. 3A, each of the upper journal bearing 42 and the lower journal bearing 43 mounted on the #1 crank journal 11 is viewed from the front along the axis Ax1 of the crankshaft 1. It has a semi-circular shape. The upper journal bearing 42 and the lower journal bearing 43 are mounted around the #1 crank journal 11 with their circumferential ends facing each other.

As shown in FIGS. 3A and 3B, the upper journal bearing 42 is formed with an oil hole 42b near the top. As described with reference to FIG. 1, the oil gallery 54 is connected to the oil hole 42b of the upper journal bearing 42, and the oil from the oil gallery 54 flows through the oil hole 42b to the journal bearings 42, 437 and the #1 crank journal 11. supplied between

In the upper journal bearing 42 and the lower journal bearing 43, inner peripheral surfaces 42a and 43a are formed by rotational surfaces generated with a straight line parallel to the axis Ax1 (see FIGS. 1 and 2) of the crankshaft 1 as a generatrix. there is That is, in the upper journal bearing 42 and the lower journal bearing 43, grooves (circumferential grooves) extending in the circumferential direction are not formed in the inner peripheral surfaces 42a and 43a, and smooth inner peripheral surfaces 42a and 43a are formed. .

The journal bearings 48 , 49 , 52 and 53 also have the same structure as the journal bearings 42 and 43 .

As shown in FIG. 4(a), each of the upper journal bearing 44 and the lower journal bearing 45 that are ring-mounted on the #2 crank journal 12 is also viewed from the front along the axis Ax1 of the crankshaft 1. It has a semi-circular shape. The upper journal bearing 44 and the lower journal bearing 45 are attached to the #2 crank journal 12 with their circumferential ends butted against each other.

As shown in FIGS. 4A and 4B, the upper journal bearing 44 also has an oil hole 44b near the top. As described with reference to FIG. 1, the oil gallery 54 is connected to the oil hole 44b of the upper journal bearing 44, and the oil from the oil gallery 54 flows through the oil hole 44b to the journal bearings 44, 45 and the #2 crank journal 12. supplied between

Among the upper journal bearing 44 and the lower journal bearing 45, the lower journal bearing 45 is a rotation surface generated with a straight line parallel to the axis Ax1 (see FIGS. 1 and 2) of the crankshaft 1 as a generatrix. 45a is formed. That is, the inner peripheral surface 45a of the lower journal bearing 45 is not formed with a groove extending in the circumferential direction (circumferential groove), but is formed with a smooth inner peripheral surface 45a.

On the other hand, as shown in FIGS. 4(a) and 4(b), the upper journal bearing 44 in which the oil hole 44b is formed is formed with a circumferential groove 44c extending in the circumferential direction in the inner peripheral surface 44a. The circumferential groove 44c is connected to the oil hole 44b, and is formed from one end side to the other end side in the circumferential direction. A circumferential groove 44c formed in the upper journal bearing 44 functions as a guide path for oil supplied from the oil hole 44b. The circumferential groove 44c also discharges foreign particles such as metal powder from the oil hole 44b of the upper journal bearing 44 to the outside when foreign particles such as metal powder enter between the journal bearings 44, 45 and the #2 crank journal 12. It also functions as a guideway to

The journal bearings 46, 47, 50, 51 also have the same structure as the journal bearings 44, 45.

4. Ensuring oil film between journal bearings 42-53 and crank journals 11-16 As described above, in the crankshaft bearing structure 100 according to the present embodiment, the #1, #4, #6 crank journals 11, 14 16, journal bearings 42, 43, 48, 49, 52, 53 without circumferential grooves are mounted on the upper and lower sides, and #2, #3, #5 crank journals 12, 13, 15 , and upper journal cranks 44, 46, 50 are provided with journal bearings 44-47, 50, 51 having circumferential grooves 44c. Securing oil films between the crank journals 11, 14, 16 and the journal bearings 42, 43, 48, 49, 52, 53 will be described with reference to FIG. Securing an oil film between the journal bearings 44 to 47, 50 and 51 will be described with reference to FIG. 5(b).

5A shows the crank journal 11 and the journal bearing 42 as an example, and FIG. 5B shows the crank journal 12 and the journal bearing 44 as an example.

As shown in FIG. 5A, since the journal bearing 42 has no circumferential groove, the gap between the inner peripheral surface 42a of the journal bearing 42 and the outer peripheral surface 11a of the crank journal 11 is is substantially the same in the entire AR1 in the width direction (direction along the axis Ax1 of the crankshaft 1). Therefore, between the inner peripheral surface 42a of the journal bearing 42 and the outer peripheral surface 11a of the crank journal 11, the resistance of the oil supplied from the oil hole 42b to the outside in the width direction (arrow C1) is relatively high. to big. Therefore, when the oil is discharged to the outside from between the inner peripheral surface 42a of the journal bearing 42 and the outer peripheral surface 11a of the crank journal 11, the pressure difference between the oil and the outside is relatively small, and the amount of oil discharged is reduced. relatively small. Therefore, an appropriate oil film is ensured between the crank journal 11 and the journal bearings 42 and 43 .

The same applies to ensuring oil films between the crank journals 14, 16 and the journal bearings 48, 49, 52, 53.

As shown in FIG. 5(b), the journal bearing 44 is formed with a circumferential groove 44c. Therefore, the gap between the inner peripheral surface 44a of the journal bearing 44 and the outer peripheral surface 12a of the crank journal 12 is wide in the area AR2 where the circumferential groove 44c is provided and narrow in the other area AR3. In the case where the areas AR2 and AR3 have wide and narrow gaps, the oil flows relatively in the area AR2 in the width direction of the journal bearing 44 (the direction along the axis Ax1 of the crankshaft 1). is small, and the resistance is relatively large in the region AR3. Therefore, when the oil is discharged from between the inner peripheral surfaces 42a, 43a of the journal bearings 44, 45 and the outer peripheral surface 12a of the crank journal 12 toward the outside in the width direction (arrow C2), the oil and the outside The pressure difference is relatively large, and the amount of oil discharged is relatively large. Although not shown, part of the oil supplied between the journal bearings 44 and 45 and the crank journal 12 is also led out to the in-shaft oil passage 56 .

However, the upper journal bearing 44 is formed with a circumferential groove 44c, and the amount of oil supplied between the journal bearings 44, 45 and the crank journal 12 is relatively large. 12 is also ensured.

The same applies to ensuring oil films between the crank journals 13, 15 and the journal bearings 46, 47, 50, 51.

5. Effects In the crankshaft bearing structure 100 according to the present embodiment, the journal bearings 42, 43, 43, 43, 43, 43, 43, 43, 43, 43, 43, 43, 43, 43, 43, 43, 43, 43, 43, 43, 43, 43, 43, 43, 43, 43, 43, 43, 43, 43, 43, 43, 43, and 43, can each having no circumferential grooves on the inner peripheral surfaces 42a, 43a. 52, 53 are selectively looped. Therefore, in a five-cylinder (odd-numbered) engine, even if a force couple occurs at both ends of the crankshaft 1, the inner circumferences of the crank journals 11, 16 and the journal bearings 42, 43, 52, 53 at both ends are The amount of oil leaking from between the surfaces 42a and 43a can be reduced. Therefore, even if a low-viscosity oil is used and the temperature of the low-viscosity oil becomes high, the oil from between the crank journals 11, 16 at both ends of the crankshaft 1 and the journal bearings 42, 43, 52, 53 The amount of oil leakage can be reduced. Therefore, even if a couple of forces occurs at both ends of the crankshaft 1, by reducing the amount of oil leaked from the both ends, the amount of oil between the crank journals 11, 16 and the journal bearings 42, 43, 52, 53 can be reduced. The lubrication of the oil pump 55 can be maintained to ensure high reliability of the engine, and an increase in the load on the oil pump 55 can be suppressed to improve fuel efficiency.

In the crankshaft bearing structure 100 according to the present embodiment, journal bearings 42, 43, 52 having no circumferential grooves on the inner peripheral surfaces 42a, 43a of the #1, #6 crank journals 11, 16 of the crankshaft 1 are provided. , 53 are selectively ringed. Therefore, in a five-cylinder (odd-numbered) engine, even if a force couple occurs at both ends of the crankshaft 1, the inner circumferences of the crank journals 11, 16 and the journal bearings 42, 43, 52, 53 at both ends are Appropriate hydraulic pressure can be secured between the surfaces 42a and 43a. In the crankshaft bearing structure 100, low-viscosity oil is used, and even when the low-viscosity oil reaches a high temperature, the journal bearings 42, 43, 52, 53 are kept in the crank journals 11, 16 at both ends of the crankshaft 1. By adopting a configuration that selectively mounts the oil from between the crank journals 11, 16 at both ends of the crankshaft 1 and the journal bearings 42, 43, 52, 53 even if a couple of forces is generated can reduce the amount of leakage.

On the other hand, in the crankshaft bearing structure 100, the #2, #3, and #5 crank journals 12, 13, and 15 among the plurality of crank journals 11 to 16 have circumferential grooves 44c on their inner circumferential surfaces 44a. Since the journal bearings 44, 46, 50 and the lower journal bearings 45, 47, 51 having no circumferential groove are mounted in the ring, the crank journals 12, 13, 15 and the journal bearings 44-47, 50, 51 A relatively large amount of oil is supplied during Further, since the upper journal bearings 44, 46, 50 have a circumferential groove 44c, if particulate foreign matter such as metal powder enters between the crank journals 12, 13, 15 and the journal bearings 44-47, 50, 51, It is also advantageous in discharging the particulate foreign matter to the outside together with the oil through the circumferential groove 44c.

Further, in the crankshaft bearing structure 100 according to the present embodiment, since the circumferential groove 44c is provided in the inner peripheral surface 44a of the upper journal bearings 44, 46, 50, the oil holes 44b of the upper journal bearings 44, 46, 50 Oil fed through is directed towards the lower journal bearings 45,47,51.

On the other hand, since the lower journal bearings 45, 47, 51 do not have circumferential grooves, they are advantageous in securing appropriate oil pressure between the lower journal bearings 45, 47, 51 and the crank journals 12, 13, 15. be.

Further, in the crankshaft bearing structure 100 according to the present embodiment, from #2, #3, and #5, shaft internal oil passages 56 to 62 connected to the adjacent crankpins 27 to 31 are formed. 47, 50, 51 and the crank journals 12, 13, 15 are partially supplied to the crank pins 27-31. In this case also, the upper journal bearings 44, 46, 50 are provided with circumferential grooves 44c, and a relatively large amount of oil flows between the journal bearings 44-47, 50, 51 and the crank journals 12, 13, 15. Therefore, even if part of the oil is supplied to the crankpins 27-31, it is possible to ensure the hydraulic pressure between the journal bearings 44-47, 50, 51 and the crank journals 12, 13, 15. can.

As described above, in the crankshaft bearing structure 100 according to the present embodiment, even when applied to a five-cylinder (odd-numbered) engine in which a couple of forces is generated at both ends of the crankshaft 1 during driving, The oil pressure between the #1, #6 crank journals 11, 16 and the journal bearings 42, 43, 52, 53 can be ensured.

[Second embodiment]
1. Schematic Configuration of Crankshaft Bearing Structure 100 A schematic configuration of a crankshaft bearing structure 200 according to a second embodiment of the present invention will be described with reference to FIG. 6 also omits illustration of a cylinder block, a connecting rod, a connecting rod bearing, and the like.

The crankshaft bearing structure 200 is applied to a 3-cylinder (odd number of cylinders) engine. As shown in FIG. 6, the crankshaft bearing structure 200 includes the crankshaft 2, a cylinder block (not shown), and a plurality of journal bearings 142-149. The crankshaft bearing structure 200 also includes an oil gallery (oil passage) 154 formed in a cylinder block (not shown) and an oil pump 155 that sends oil to the oil gallery 154 .

Crankshaft 2 extends along axis Ax2. Also in the present embodiment, the direction in which the axis Ax2 extends is the direction of the row of cylinders of the engine and corresponds to the "predetermined direction". The crankshaft 2 has a plurality of crank journals 111 to 114 spaced apart from each other in the direction along the axis Ax2. The crankshaft 2 also has crankpins 127-129 arranged between adjacent crank journals 111-114 in the direction along the axis Ax2.

In the crankshaft 2, the crank webs 117-122 connect the crank journals 111-114 and the crank pins 127-129 adjacent to each other along the axis Ax2. A counterweight is integrally formed at the other end of each of the crank webs 117 to 122 in the direction perpendicular to the axis Ax2 of the crankshaft 2 .

In this embodiment, the crank journal 111 may be referred to as the #1 crank journal, the crank journal 112 as the #2 crank journal, and the crank journal 113 as the #3 crank journal.

The journal bearings 142-149 are interposed between the cylinder block bearings (not shown) and the crank journals 111-114. Each of the journal bearings 142 to 149 has a semi-annular shape when viewed from the front along the axis Ax2 of the crankshaft 2 . The journal bearings 142-149 are sliding bearings made of metal material. In this embodiment, the journal bearings 142, 144, 146 correspond to "upper journal bearings", and the journal bearings 143, 145, 147 correspond to "lower journal bearings".

An upper journal bearing 142 and a lower journal bearing 143 are attached to the #1 crank journal 111, an upper journal bearing 144 and a lower journal bearing 145 are attached to the #2 crank journal 112, and an upper journal bearing 146 and a lower journal bearing 146 are attached to the #2 crank journal 112. The journal bearing 147 is mounted around the #3 crank journal 113 .

In this embodiment, the crank journals 112 and 113 correspond to "part of the crank journals", and the journal bearings 144 to 147 correspond to "first journal bearings". Further, the crank journals 11, 114 correspond to "another crank journal", and the journal bearings 142, 43, 148, 149 correspond to a "second journal bearing".

Between the journal bearings 142-149 and the crank journals 11-14, the crankshaft 2 is rotatable around the axis Ax2, and a fine gap is formed in which an oil film is formed. Each of the upper journal bearings 142 , 144 , 146 , 148 has an oil hole connected to an oil gallery 154 as an oil supply port for forming this oil film.

The configuration 5 of the oil gallery 154 and the oil pump 15 is the same as the oil gallery 54 and the oil pump 55 in the first embodiment. Also in the present embodiment, so-called low-viscosity oil is used as the oil.

2. Shaft internal oil passages 156 to 159 of crankshaft 2
The crankshaft 2 of the crankshaft bearing structure 200 according to the present embodiment is also formed inside the shaft and has in-shaft oil passages 156 to 159 that are flow passages for oil. The in-shaft oil passages 56 to 62 provided in the crankshaft 1 will be described with reference to FIG.

As shown in FIG. 7, in the crankshaft 1, openings are not provided in the outer peripheral surfaces 111a and 114a of the #1 and #4 crank journals 111 and 114, respectively. On the other hand, openings 112b and 113b are provided in the outer peripheral surfaces 112a and 113a of the #2 and #3 crank journals 112 and 113, respectively.

Openings 127b to 129b are also provided on the outer peripheral surfaces 127a to 129a of the crankpins 127 to 129, respectively. Inside the crankshaft 2, shaft internal oil passages 156 to 158 connecting the opening 112b of the crank journal 112 and the openings 127b and 128b of the crankpins 127 and 128 are formed. Further, an in-shaft oil passage 159 connecting the opening 113b of the crank journal 113 and the opening 129b of the crank pin 129 is provided.

In the crankshaft bearing structure 200 according to the present embodiment, no shaft internal oil passage is formed from the outer peripheral surface 127a of the crankpin 127 toward the crank journal 111. An internal shaft oil passage toward the journal 114 is not formed.

A part of the oil supplied from the oil gallery 154 between the journal bearings 144, 145 and the #2 crank journal 112 is introduced into the in-shaft oil passage 156 as indicated by the arrow E1, and flows inside the crankshaft 2. It is distributed to an in-shaft oil passage 157 and an in-shaft oil passage 158 . As indicated by arrows E2 and E3, oil flows from the shaft internal oil passages 157 and 158 through the openings 127b and 128b of the crankpins 127 and 128 and between the crankpins 127 and 128 and connecting rod bearings (not shown). supplied.

Also, part of the oil supplied from the oil gallery 154 between the journal bearings 146, 147 and the #3 crank journal 113 is introduced into the shaft internal oil passage 159 as indicated by arrow E4 and is indicated by arrow E5. , through the opening 129b of the crankpin 129 and supplied between the crankpin 129 and the connecting rod bearing (not shown).

In the crankshaft bearing structure 200 according to this embodiment, similar to the journal bearings 42 and 43 described with reference to FIGS. No circumferential groove is provided.

On the other hand, the upper journal bearings 144 and 146 of the journal bearings 144 to 147 that are dried on the #2 and #3 crank journals 112 and 113 have the upper journal bearings described with reference to FIGS. Similar to 44, a circumferential groove is provided on the inner peripheral surface.

That is, in the crankshaft bearing structure 200 according to the present embodiment as well, the inner peripheral surfaces of the #1 and #4 crank journals 111 and 114 located at both ends in the direction along the axis Ax2 of the crankshaft 2 are Upper journal bearings 144, 148 with circumferential grooves and lower journal bearings 145, 149 without circumferential grooves are selectively mounted.

In the crankshaft bearing structure 200 having the above configuration, as in the crankshaft bearing structure 100 according to the first embodiment, even when a couple of forces are generated at both ends of the crankshaft 2 during driving, The amount of oil leakage from between the #1, #4 crank journals 111, 114 and the journal bearings 142, 143, 148, 149 can be kept low. Therefore, in the crankshaft bearing structure 200 according to the present embodiment as well, even if a force couple occurs at both ends of the crankshaft 2, the #1 and #4 crank journals 111 and 114 and the journal bearing 142 at both ends of the crankshaft 2 are , 143, 148, and 149 can be reduced to ensure high engine reliability and improve fuel efficiency.

[Modification]
In the first embodiment, the crankshaft bearing structure 100 applied to a 5-cylinder engine is taken as an example, and in the second embodiment, the crankshaft bearing structure 200 applied to a 3-cylinder engine is taken as an example. The present invention can be widely applied to engines with odd-numbered cylinders of 7 or more cylinders.

In the first embodiment, the #4 crank journal 14 of the crankshaft 1 is also provided with the journal bearings 48 and 49 having no circumferential groove on the inner peripheral surface. It is also possible to mount journal bearings having circumferential grooves on the inner peripheral surfaces of the four crank journals. That is, in the present invention, it is sufficient to mount journal bearings having no circumferential grooves on the inner peripheral surfaces of at least the crank journals located at both ends in the axial direction of the crankshaft.

In the first embodiment and the second embodiment, the shaft internal oil passages 56 to 62 and 156 to 159 are formed in the crankshafts 1 and 2, but in the present invention, the shaft internal oil passages are not provided. Not required.

In the first embodiment, the inner peripheral surfaces 44a of the upper journal bearings 44, 46, 50 are provided with the peripheral grooves 44c, and the inner peripheral surfaces 45a of the lower journal bearings 45, 49, 51 are not provided with peripheral grooves. However, in the present invention, a circumferential groove may be provided in the lower journal bearing that is mounted around the crank journal together with the upper journal bearing in which the circumferential groove is formed.

In the second embodiment as well, the inner peripheral surfaces of the upper journal bearings 144 and 146 are provided with circumferential grooves, and the inner peripheral surfaces of the lower journal bearings 145 and 147 are not provided with circumferential grooves. A circumferential groove may also be provided for the lower journal bearing, which is mounted on the crank journal together with the upper journal bearing having the groove.

1, 2 Crankshaft 11-16, 111-114 Crank journal 12b, 13b, 15b, 112b, 113b Opening 27-31, 127-129 Crank pin 27b, 28b, 29b, 30b, 31b, 127b, 128b, 129b Opening 42 , 44, 46, 48, 50, 52, 142, 144, 146, 148 Upper journal bearing 42b, 44b Oil hole 44c Circumferential groove 43, 45, 47, 49, 51, 53, 143, 145, 147, 149 Lower journal Bearing 54, 154 Oil gallery (oil passage)
56-62, 156-159 Shaft internal oil passages 100, 200 Crankshaft bearing structure

Claims (3)

A crankshaft bearing structure applied to an odd-numbered cylinder engine,
a crankshaft extending in 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 shaft support portions arranged to surround the radial outer sides of the plurality of crank journals, the plurality of shaft support portions rotatably supporting the crankshaft;
a plurality of journal bearings mounted on each of the plurality of crank journals between each of the plurality of crank journals and each of the plurality of shaft supports in a state in which the crankshaft is rotatable;
with
The cylinder block has an oil passage,
The plurality of journal bearings include a first journal bearing mounted on a portion of the crank journal among the plurality of crank journals and another crank excluding the portion of the crank journal among the plurality of journal bearings. a second journal bearing encircled by the journal;
The first journal bearing has an oil hole that is connected to the oil passage at an upper portion and supplies oil from the oil passage between the journal bearing and the crank journal, and the oil hole on the inner peripheral surface of the journal bearing. a circumferentially extending circumferential groove connected to the
The second journal bearing has an inner peripheral surface formed by a rotating surface generated with a straight line parallel to the predetermined direction as a generatrix, and an upper part connected to the oil passage, and the oil from the oil passage is transferred to the inner peripheral surface. and an oil hole for supplying between the crankshaft,
The second journal bearing is attached to at least one of the plurality of crank journals located at both ends in the predetermined direction.
Crankshaft bearing structure. A crankshaft bearing structure according to claim 1, wherein
each of the plurality of journal bearings is composed of an upper journal bearing and a lower journal bearing each having a semi-annular shape in a front view from the predetermined direction;
The circumferential groove in the first journal bearing is provided only in the upper journal bearing,
Crankshaft bearing structure. In the crankshaft bearing structure according to claim 1 or claim 2,
The crankshaft is an oil passage extending only from a crank pin arranged between the crank journals adjacent to each other in the predetermined direction and from the part of the crank journal to which the first journal bearing is mounted, an in-shaft oil passage for guiding oil to the crank pin adjacent to the crank journal;
Crankshaft bearing structure.

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