JP2008196398A - Oil supply structure of crankshaft - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide oil an supply structure of a crankshaft allowing reduction in size of an oil pump, by reducing leakage of oil from between a bearing and a journal part of a crankshaft. <P>SOLUTION: The journal part 22 of the crankshaft includes: a shaft oil passage 40 leading the oil supplied to a crankpin; and a guide groove 30 having an opening part 31 to which the shaft oil passage 40 is opened and which is opened to an outer peripheral surface A of the journal part 22. The guide groove 30 extends in a rotational direction of the crankshaft 30 from a downstream end part 33 to which the shaft oil passage 40 is opened. A bearing surface 51e of a bearing half body 51 of the bearing 50 is provided with an oil supply groove 53 supplying the oil to the guide groove 30. The oil supply groove 53 is radially faces the guide groove 30, and an axial width W5 of the oil supply groove 53 is smaller than an axial width W3 of the guide groove 30. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an oil supply structure for a crankshaft including a bearing provided with an oil supply groove, and a crankshaft having a journal portion supported by the bearing and supplied with oil in the oil supply groove. The crankshaft oiling structure is provided, for example, in an internal combustion engine.

The oil supply structure of the crankshaft is composed of a bearing to which oil discharged from an oil pump is supplied, and a crankshaft having a journal portion supported by the bearing, and the journal portion has oil supplied to the crankpin. It is known that an in-shaft oil passage for guiding the shaft and a guide groove in which the in-shaft oil passage opens are provided. (For example, see Patent Document 1)
And the oil pressure supplied to the crankpin is increased by the guide groove provided extending in the rotation direction of the crankshaft, so that the discharge pressure of the oil pump can be reduced, and hence the power for driving the oil pump can be reduced. Become.
Japanese Utility Model Publication No. 6-43202

  By the way, in the process in which oil is supplied to the guide groove from the oil supply groove provided in the bearing that supports the journal portion, oil leaks from between the bearing and the journal portion, so that a required oil supply amount to the crank pin is ensured. In order to achieve this, it is necessary to supply an amount of oil that compensates for this amount of leakage, which hinders downsizing of the oil pump.

  The present invention has been made in view of such circumstances, and by reducing the amount of oil leakage between the bearing and the journal portion of the crankshaft, the crankshaft of which the size of the oil pump can be reduced. The object is to provide an oil supply structure.

The invention according to claim 1 is an oil supply structure of a crankshaft comprising a bearing to which oil discharged from an oil pump is supplied and a crankshaft having a journal portion supported by the bearing, wherein the journal The shaft is provided with an in-shaft oil passage that guides oil supplied to the crankpin, and a guide groove that is open to the outer peripheral surface of the journal portion while the in-shaft oil passage is open to the bearing surface of the bearing. Is provided with an oil supply groove for supplying oil to the guide groove, and the guide groove extends in a rotation direction of the crankshaft from a portion where the in-shaft oil passage opens. The groove and the guide groove are arranged to face each other in the radial direction, and the oil supply groove has a crankshaft oil supply structure in which an axial width of the oil supply groove is smaller than an axial width of the guide groove.
According to a second aspect of the present invention, in the crankshaft oil supply structure according to the first aspect, the bearing includes a first bearing member and a second bearing member that are divided in a circumferential direction, and the oil supply groove is the first oil supply groove. It is provided only in the bearing member, and the depth of the oil supply groove gradually decreases as it approaches the circumferential end of the first bearing member.

According to the first aspect of the present invention, the required oil pressure of the oil supplied to the crank pin is secured by the pressurizing action of the guide groove, and the axial width of the oil supply groove for supplying oil to the guide groove is the guide width. Since it is smaller than the axial width of the groove, the seal length in the axial direction between the bearing and the journal portion is increased, and the amount of oil leakage between the bearing surface and the journal portion in the radial direction is reduced. For this reason, the amount of oil supplied to the oil supply groove can be reduced, the oil pump can be reduced in size, and the output loss caused by stirring the oil leaked from the crankshaft is reduced. Furthermore, since the discharge pressure of the oil pump can be reduced by the guide groove, the leakage amount can be further reduced.
According to the second aspect of the present invention, since oil leakage at the abutting portions of the first and second bearing members constituting the bearing can be suppressed, the amount of oil leakage from the journal portion can be further reduced. In addition, since the depth of the oil supply groove gradually decreases as it approaches the circumferential end of the first bearing member, an oil film having a gradually changing thickness is formed between the journal and the journal. It is supported stably over the entire circumference.

Hereinafter, embodiments of the present invention will be described with reference to FIGS.
Referring to FIG. 1, the crankshaft oiling structure to which the present invention is applied is provided in an internal combustion engine E mounted on a vehicle. An internal combustion engine E as a multi-cylinder internal combustion engine is an in-line four-cylinder internal combustion engine, a cylinder block 1 having a plurality of four cylinders 1a, a cylinder head 2 coupled to an upper portion of the cylinder block 1, and a cylinder block 1 The engine body is composed of a lower block 3 and an oil pan 4 which are sequentially coupled to the lower part 1b of the engine and which together with the lower part 1b form a crank chamber 5. Here, the lower part 1 b, the lower block 3, and the oil pan 4 constitute a crankcase that forms the crank chamber 5.

In the specification, the axial direction is the direction of the rotation center line Le of the crankshaft 20, and the radial direction and the circumferential direction are a radial direction and a circumferential direction around the rotation center line Le, respectively.
In the embodiment, as shown in FIG. 1, the direction parallel to the cylinder axis Lc of the cylinder 1a is defined as the up-down direction, and the axial direction is defined as the left-right direction. When one of the left and right is one in the axial direction, the other of the left and right is the other in the axial direction.

  The piston 6 fitted to each cylinder 1a so as to be able to reciprocate is a crankshaft rotatably supported by the lower part 1b of the cylinder block 1 via a connecting rod 7 and a plurality of five bearings 50 as a predetermined number. Linked to 20. The piston 6 driven by the pressure of the combustion gas generated by the combustion of the air-fuel mixture in the combustion chamber 8 provided in the cylinder head 2 rotates the crankshaft 20.

  Each bearing 50 is held by a bearing wall 10 as an upper holding portion provided integrally with the lower portion 1b, and a bearing cap 11 as a lower holding portion coupled to the bearing wall 10 by a bolt. Accordingly, each bearing 50 is held by a bearing holding member constituted by the bearing wall 10 and the bearing cap 11, and the bearing holding member is provided integrally with the lower portion 1 b of the cylinder block 1. Each bearing 50 is supplied with oil discharged from an oil pump 60 driven by the power of the crankshaft 20.

The crankshaft 20 is disposed between the predetermined number of journal portions 21 to 25 supported by the bearings 50 and the journal portions 21, 22; 22, 23; 23, 24; 24, 25 adjacent in the axial direction. And a plurality of crank pins 27 which are connected to a pair of crank webs 26 and rotatably connect the large end of the connecting rod 7 via a bearing 12, and these journal parts 21 to 25, This is an integral crankshaft in which the crank web 26 and the crankpin 27 are integrally formed.
The predetermined number of journal portions 21 to 25 are a pair of end journal portions 21 and 25 disposed at both ends in the axial direction and an intermediate journal disposed between both end journal portions 21.25 in the axial direction. Divided into parts 22-24.

  A shaft end portion 20a extending leftward from the end journal portion 25 and serving as a free end of the crankshaft 20 includes an auxiliary machine group including an AC generator provided in the internal combustion engine E as a member driven by the internal combustion engine E. A crank pulley 13 constituting a transmission mechanism for driving is provided. Further, a shaft end portion 20b extending rightward from the end journal portion 21 and serving as a free end of the crankshaft 20 is used as a member driven by the internal combustion engine E to transmit and block rotation of the crankshaft 20 to the transmission. A transmission clutch (not shown) is provided.

Hereinafter, the oil supply structure of the crankshaft composed of the bearing 50 and the crankshaft 20 will be specifically described.
Referring to FIGS. 1 to 3, all journal portions 21 to 25 are provided with a first journal portion provided with an in-shaft oil passage 40 for supplying oil to each crankpin 27 and a second journal portion without an in-shaft oil passage 40. It is divided into the journal part. A plurality of, in this case, two intermediate journal portions 22 and 24 serving as the first journal portions are respectively provided with a pair of in-shaft oil passages 40 for guiding oil to a pair of crank pins 27 serving as oil receiving portions. In addition, a communication oil passage 43 that allows the both-shaft oil passages 40 to communicate with each other, and a pair of guide grooves 30 in which the in-shaft oil passages 40 open are provided. In addition, the plurality of the second journal parts are divided into two end journal parts 21 and 25 and one intermediate journal part 23.

  Referring also to FIG. 4, the in-shaft oil passage 40 provided in the crankshaft 20 is branched from the upstream in-shaft oil passage 41 opened in the guide groove 30 and the upstream in-shaft oil passage 41. It is composed of a downstream-side in-shaft oil passage 42 opened in the outer peripheral surface of the pin 27. The pair of in-shaft oil passages 40 communicate with each other through a communication oil passage 43 formed of a straight hole passing through the rotation center line Le in the journal portions 22 and 24. Each of the upstream side in-shaft oil passage 41 and the downstream side in-shaft oil passage 42 is configured by a straight hole formed by machining such as drilling, and has a circular passage cross section. The oil is guided to the crankpin 27 and the oil after being guided to the crankpin 27 and lubricating the bearing 50 is jetted into the crank chamber 5 to be used for lubrication of the lubricated portion in the crank chamber 5.

  2 and 3, the guide groove 30 having the opening 31 opened at the central position in the axial direction on the outer peripheral surface A of the journal portions 22 and 24 is a portion where the in-shaft oil passage 41 is opened. It has a downstream end 33 and an upstream end 32 positioned forward in the rotational direction R with respect to the downstream end 33 positioned rearward in the rotational direction R of the crankshaft 20. The guide groove 30 extends in the rotational direction R of the crankshaft 20 from the downstream end 33 that is closed by the wall surface 34 along the radial direction on the counter-rotating direction side. The opening 31 opens over the downstream end 33 and the upstream end 32.

  The depth of the guide groove 30 becomes gradually shallower as it goes in the rotation direction R of the crankshaft 20, and the passage area of the guide groove 30 becomes gradually larger as it goes in the counter-rotation direction. The maximum value of the axial width W3 of the guide groove 30 is substantially equal to the diameter W4 of the inlet of the in-shaft oil passage 41 opened in the guide groove 30. Here, the axial width W <b> 3 is the width in the axial direction at the opening 31.

During the rotation of the crankshaft 20, the oil in the gap C around the outer peripheral surface A flows into the guide groove 30 from the upstream end 32 side of the opening 31, and enters the downstream end 33 within the guide groove 30. It flows toward. At this time, since the passage area of the guide groove 30 gradually increases toward the downstream end 33, the oil speed decreases in the guide groove 30 from the upstream end 32 toward the downstream end 33, and the oil movement The pressure is converted into a static pressure, and the oil at the downstream end 33 has a higher oil pressure than the oil at the gap C and the upstream end 32. Then, the oil having the increased hydraulic pressure is supplied to the crankpin 27 (see FIG. 1) through the in-shaft oil passage 40. Therefore, the oil flowing into the guide groove 30 is converted into a static pressure in the guide groove 30, that is, the hydraulic pressure is increased by the pressurizing action of the guide groove 30, and the oil passage 40 in the shaft is increased. Flow into.
In addition, on the outer peripheral surface A, no groove that forms an oil passage is formed other than the guide groove 30.

  Each bearing 50 arranged in a state in which movement in the axial direction and the circumferential direction is regulated in a bearing hole made of a circular hole formed by the bearing wall 10 and the bearing cap 11 is a cylindrical shape made of plain metal, respectively. A semi-cylindrical first bearing half 51 as a first bearing member divided into two in the circumferential direction, and a semi-cylindrical second bearing half 52 as a second bearing member; It is a half-type bearing composed of

  Each bearing 50 is held by the bearing wall 10 and the bearing cap 11 in a state where the circumferential end portions 51a, 52a; 51b, 52b of both bearing halves 51, 52 are abutted with each other. The end portions 51a, 52a; 51b, 52b are provided with crush reliefs 51c, 52c that increase the radial gap C between the butted portion and the journal portions 21-25. Due to the crush reliefs 51c and 52c, due to an assembly error of the bearing cap 11 with respect to the bearing wall 10 or the like, a part of the abutted end portions 51a and 52a; Contact with 21-25 is prevented.

  Referring also to FIG. 5, among the first and second bearing halves 51 and 52, only the bearing half 51 that forms an oil passage 64 to be described later in cooperation with the bearing wall 10, An arcuate oil supply groove 53 serving as an oil passage for supplying oil to 25 and one or a plurality of, here, three oil holes 54 for guiding the oil to the oil supply groove 53 are provided. On the other hand, the bearing half 52 is not provided with a groove or hole constituting an oil passage for supplying oil to the gap C.

The oil holes 54 are holes that open into the outer peripheral surface of the bearing half 51 and the oil supply groove 53 and penetrate the bearing half 51 in the radial direction, and are arranged at equal intervals in the circumferential direction.
In the bearing half 51, the oil supply groove 53 is provided at a central position in the axial direction on a bearing surface 51e formed of an inner peripheral surface facing the outer peripheral surface A of the journal portions 21 to 25 corresponding in the radial direction. The oil supply groove 53 has an opening 53 a that opens to the bearing surface 51 e and is disposed so as to face the guide groove 30 in the radial direction, and supplies oil in the oil supply groove 53 to the guide groove 30. The oil supply groove 53 is provided in a portion of the bearing half 51 excluding the circumferential end portions 51a and 51b, and the depth of the oil supply groove 53 gradually decreases as it approaches the both end portions 51a and 51b in the circumferential direction.

  The axial width W5 of the oil supply groove 53 is smaller than the axial width W3 of the guide groove 30 (see FIG. 3), and the oil supply groove 53 is disposed in the axial formation range of the guide groove 30 in the axial direction. Is done. Here, the axial width W5 is a width in the axial direction at the opening 53a. For this reason, the seal length S in the axial direction formed by the radially opposing portions of the bearing half 51 and the journal portions 22, 24 (see FIG. 1) is the guide groove 30 and the axial width W5 of the oil supply groove is the guide groove 30. Oil leakage between the bearing half 51 and the journal portions 22 and 24 in a range other than the portion where the guide groove 30 is positioned in the circumferential direction. It is suppressed. Then, as seen from the radial direction, the oil supply groove 53 and the guide groove 30 overlap each other (that is, the oil is directly supplied from the oil supply groove 53 to the guide groove 30, and is shown by the dotted cross hatching in FIG. As for the minimum value of the delivery area which is the area of the part), the axial width W5 of the oil supply groove 53 is set so that the passage area of the in-shaft oil passage 40 is also increased. As a result, a sudden increase in pressure loss due to the reduction in the axial width W5 of the oil supply groove 53 is prevented, and the required amount of oil supplied to the crank pin 27 (see FIG. 1) is ensured.

  Referring to FIGS. 1 and 2, the oil discharged from the oil pump 60 and guided to the main gallery 61 is inserted into the bearing oil passages constituted by the oil supply grooves 53 and the oil holes 54 of the respective bearings 50. It is guided through a bearing wall 10 of the holding member and a bearing outer oil passage provided in the cylinder block 1. Therefore, the predetermined number of the five bearing outer oil passages for guiding the oil discharged from the oil pump 60 to each bearing 50 branches off from the main gallery 61 as an oil passage common to the bearing outer oil passages. ing.

  Each of the bearing outer oil passages is provided with a semicircular groove provided on the bearing wall 10 and opening radially inward toward the outer peripheral surface A, and a bearing cap 11 of the bearing wall 10. The oil passage 63 is composed of a groove provided on the mating surface, and the oil passage 62 is composed of a hole provided in the cylinder block 1.

  Then, for each journal portion 21 to 25, the oil in the main gallery 61 is guided to the oil supply groove 53 through the oil passage 62, the oil passage 63, the oil passage 64, and the oil hole 54 in sequence, and the oil in the oil supply groove 53 further flows. It is supplied to the gap C between the guide groove 30 and both bearing halves 51, 52 and the journal portions 21-25. Therefore, the oil supply for supplying the oil to the journal portions 21 to 25 by the bearing internal oil passage formed of the oil supply groove 53 and the oil hole 54 and the bearing external oil passage formed of the plurality of oil passages 62, 63, 64. Paths 71-75 are configured. Each bearing 50 provided with the oil supply groove 53 and the oil hole 54, and the cylinder block 1 and the bearing wall 10 provided with the oil passages 62, 63, 64 support the crankshaft 20 rotatably and the predetermined number. These oil passage forming members are provided with the five oil supply passages 71 to 75. The five oil supply passages 71 to 75 include oil supply passages 72 and 74 as first oil supply passages for supplying oil to the journal portions 22 and 24 in which the in-shaft oil passage 40 is provided, and journals in which the in-shaft oil passage 40 is not provided. It is divided into oil supply passages 71, 73, 75 as second oil supply passages for supplying oil to the portions 21, 23, 25.

  Unlike the journal portions 22 and 24, the journal portions 21, 23, and 25 in which the in-shaft oil passage 40 is not provided can reduce the required amount of oil compared to the journal portions 22 and 24. Therefore, the oil supply amount in the oil supply passages 71, 73, 75 is made smaller than the oil supply amount in the oil supply passages 72, 74. Therefore, at least one of the oil passages in the bearing and the oil passage outside the bearing constituting the oil supply passages 71, 73, and 75, here, the oil passage 62 of the oil passages 62 and 63 of the oil passage outside the bearing. In addition, orifices 81, 83, 85 are provided as flow restricting means for restricting the amount of oil supplied to the journal portions 21, 23, 25.

In addition, a relatively large bend occurs at both shaft end portions 20a and 20b which are free ends of the crankshaft 20. Therefore, among the journal portions 21 to 25, the end journal portions 21 and 25 are large load journal portions that have a large load, and the intermediate journal portions 22 to 24 have a smaller load than the end journal portions 21 and 25. It is a small-load journal that works. The bearings 50b and 50a, which are the end bearings that support the end journal portions 21 and 25 closest to the shaft end portions 20a and 20b, include bearings 50 that support the journal portions 22 to 24 in order to suppress wear. A larger amount of oil is supplied than For this reason, the orifice diameter of the orifice 83 is set smaller than the orifice diameters of the orifices 81 and 85, and the oil amount restriction amount in the oil supply passage 73 is larger than the oil amount restriction amount in the oil supply passages 71 and 75. To be bigger. As a result, the journal units 21 and 25 are supplied with a larger amount of oil than the journal unit 23.
Here, the amount of oil supplied to both end journal portions 21 and 25 may be the same, or may be set to a different amount of oil depending on the load acting on the shaft end portions 20b and 20a.

Next, operations and effects of the embodiment configured as described above will be described.
In the crankshaft oil supply structure, the journal portions 21 to 25 of the crankshaft 20 are provided with a guide groove 30 in which an in-shaft oil passage 40 that guides oil supplied to the crankpin 27 is opened, and a bearing surface 51e of the bearing 50 is provided. Is provided with an oil supply groove 53 for supplying oil to the guide groove 30. The guide groove 30 extends in the rotational direction R of the crankshaft 20 from the downstream end 33 where the in-shaft oil passage 40 is opened. The groove 53 and the guide groove 30 are arranged to face each other in the radial direction, and the axial width W5 of the oil supply groove 53 is smaller than the axial width W3 of the guide groove 30, so Since the required oil pressure of the oil supplied to 27 is secured and the axial width W5 of the oil supply groove 53 for supplying oil to the guide groove 30 is smaller than the axial width W3 of the guide groove 30, The seal length S in the axial direction between the journal parts 22 and 24 becomes longer, In the radial direction, the amount of oil leakage between the bearing surface 51e and the journal portions 22 and 24 is reduced. For this reason, the amount of oil supplied to the oil supply groove 53 can be reduced, the oil pump 60 can be reduced in size, and the output loss caused by stirring the oil leaked from the crankshaft 20 is reduced. Engine output is improved. Furthermore, since the discharge pressure of the oil pump 60 can be reduced by the guide groove 30, the leakage amount can be further reduced.

  For example, as shown in FIG. 6, the present invention has a medium / high-speed rotation as compared with the first comparative example in which the guide groove 30 is provided and the axial width W5 of the oil supply groove 53 is the same as the axial width W3 of the guide groove 30. The required oil supply amount of the oil pump 60 is decreasing in the region. This reduction effect tends to increase as the rotational speed increases.

  Further, as shown in FIG. 7, in the present invention in which the guide groove 30 is provided and the amount of oil leakage is reduced by reducing the axial width W5 of the oil supply groove 53, the guide groove 30 is provided. Since the minimum hydraulic pressure greater than the minimum hydraulic pressure of Comparative Example 2 is ensured, the required oil supply amount can be reduced while reducing the discharge pressure, and the oil pump 60 can be downsized.

  The bearing 50 is composed of a bearing half 51 and a bearing half 52 that are divided in the circumferential direction. The oil supply groove 53 is provided only in the bearing member 51 of the two bearing halves 51 and 52. Since the depth gradually decreases as it approaches the circumferential ends 51a and 51b of the bearing half 51, oil leakage at the abutting portions of both bearing halves 51 and 52 can be suppressed. The amount of oil leakage from ~ 25 can be further reduced. In addition, since the depth of the oil supply groove 53 gradually decreases as it approaches the circumferential end portions 51a and 51b, an oil film whose thickness gradually changes is formed between the journal portions 21 to 25, and the journal portion 21. ˜25 is stably supported by the bearing 50 over the entire circumference.

  The journal portions 21 to 25 of the crankshaft 20 include journal portions 22 and 24 in which an in-shaft oil passage 40 for supplying oil to each crankpin 27 is provided, and journal portions 21, 23 and 25 in which no in-shaft oil passage 40 is provided. The oil supply passages 71 to 75 for supplying oil to the journal portions 21 to 25 are provided with oil supply passages 72 and 74 for supplying the journal portions 22 and 24 and oil supply passages 71 for supplying the journal portions 21, 23 and 25, In the crankshaft oiling structure divided into 73 and 75, all the oil supply passages 71 to 75 are branched from the main gallery 61. By providing orifices 81, 83, and 85 that reduce the amount of oil supplied at 74, respectively, the orifices 81, 83, and 85 are provided in the oil supply passages 71, 73, and 75. By reducing the oil pressure between the bearing 25 and each bearing 50, an in-shaft oil passage 40 is provided. The amount of oil supplied to the non-journal parts 21, 23, 25 can be made smaller than the amount of oil supplied to the journal parts 22, 24 provided with the in-shaft oil passage 40, so the required amount of oil supplied to the crank pin 27 was secured. In addition, the amount of oil leakage from the journal parts 21, 23, 25 is reduced, and the oil pump 60 can be downsized.

  A plurality of journal portions 21, 23, 25 that are not provided with the in-shaft oil passage 40 are end journal portions 21, 25 that are arranged at the ends in the axial direction among all the journal portions 21-25 of the crankshaft 20. The journal portion is divided into an intermediate journal portion 23 disposed between both end journal portions 21 and 25 in the axial direction, and the amount of oil supplied to the intermediate journal portion 23 is smaller than that of the end journal portions 21 and 25, thereby 21, 23, and 25, more oil is supplied to the end journal portions 21 and 25 to which a large load acts, while the intermediate journal portion 23 to which a smaller load acts than the end journal portions 21 and 25. Since less oil is supplied compared to the end journal parts 21, 25, the journal parts 21, 23, 25 while optimizing the amount of oil supply between the journal parts 21, 23, 25 where the plurality of in-shaft oil passages 40 are not provided. Further reduce oil leakage from 23 and 25 You can.

Hereinafter, an embodiment in which a part of the configuration of the above-described embodiment is changed will be described with respect to the changed configuration. In addition, the same code | symbol is used as needed about the same member etc. as the member of the said embodiment, or a corresponding member.
As the guide grooves 30 ₁ in FIG. 2 indicated by a two-dot chain line, so that the bottom wall surface 35 is located at the rotational axis Le closer than the position of shaft oil passage 40 of the guide groove 30 _1, the guide groove 30 The depth of ₁ may be increased. Thus, the pressure loss in the guide groove 30 ₁ is reduced, the hydraulic pressure is increased at the downstream end of the guide groove 30 _1.
Further, the cost can be reduced by not performing the process of smoothly bending the portion 39 (see FIG. 2) in the vicinity of the communicating portion between the in-shaft passage 40 and the guide groove 30 as shown.
Further, as the guide groove 30 ₂ shown in FIG. 2 by the two-dot chain line, by a shape in the form a convex to the bottom wall 36 radially outward, and is smoothly curved, the guide groove 30 ₂ pressure loss in is reduced, the pressure at the downstream end of the guide groove 30 ₂ is enhanced.

Referring to FIG. 8, as the downstream end portion 33 is covered by the outer peripheral surface A from the outer side in the radial direction, intended to guide grooves 30 ₃ is formed by a hole, the oil at the downstream end portion 33 from the guide groove 30 ₃ because flow out is prevented, and it is possible to use the oil dynamic pressure of the guide groove 30 in ₃ efficiently, further hydraulic enhanced. The bottom wall surface 37 has a shape that protrudes radially outward and is smoothly curved from the outer peripheral surface A of the journal portion 22, so that the oil surrounding the outer peripheral surface A is smoothly guided into the guide groove 30. Therefore, the pressure loss is reduced and the hydraulic pressure at the downstream end 33 is increased.

Referring to FIG. 9, as the downstream end portion 33 is covered by the outer peripheral surface A from the outer side in the radial direction, if the guide grooves 30 ₄ are formed by holes, by pores is straight hole, the cost Can be reduced. Further, the communication oil passage 43 (see FIG. 2) for communicating the pair of in-shaft oil passages 40 can be omitted.

  As an arrangement of the in-shaft oil passage 40, a straight in-shaft oil passage 40 may open on the outer peripheral surface of the crankpin 27 as shown by a two-dot chain line in FIG. 4. Further, as shown in FIG. 10, the upstream-side in-shaft oil passage 41 of the in-shaft oil passage 40 passes through the radial oil passage 41 a orthogonal to the rotation center line Le and the rotation center line Le to the rotation center line Le. The downstream axial oil passage 42 may be branched from the axial oil passage 41b.

The flow rate limiting means includes the following means.
With respect to the bearing 50 that supports the second journal portions 21, 23, 25, the diameter of the oil hole 54 is reduced, or the axial width W5 or the circumferential width of the oil supply groove 53 is reduced.
The passage area of the second oil supply passages 71, 73, 75 is made smaller than the passage area of the first oil supply passages 72, 74 by reducing the diameter of the holes forming the second oil supply passages 71, 73, 75 and the inner diameter of the conduit. Also make it smaller.

The internal combustion engine may be a V type engine such as a V type 6 cylinder or a V type 8 cylinder.
Although the internal combustion engine is used for a vehicle in the embodiment, it may be used for a ship propulsion device such as an outboard motor having a crankshaft oriented in the vertical direction.
The oil supply structure for the crankshaft of the present invention may be provided in a machine other than the internal combustion engine.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a cross-sectional view of a principal part in a plane passing through a rotation center line of a crankshaft and parallel to a cylinder axis of an internal combustion engine having a crankshaft oiling structure to which the present invention is applied. It is principal part sectional drawing in the 2-2 line of FIG. FIG. 3 is a view taken in the direction of the arrow 3a in FIG. 2, and the bearing is a cross-sectional view taken along the line 3b-3b in FIG. It is a schematic diagram which shows arrangement | positioning of the oil path in a shaft when the crankshaft of FIG. 1 is seen from upper direction. It is a figure of the bearing half body which comprises a bearing in 5 arrows of FIG. It is a graph which shows the relationship between an engine speed and the amount of oil supply of an oil pump. It is a graph which shows the relationship between the axial direction width | variety of an oil supply groove | channel, and the minimum hydraulic pressure with respect to a crankpin. (A) is sectional drawing equivalent to FIG. 2 which shows the modification of the guide groove provided in the journal part of the crankshaft of the internal combustion engine of FIG. 1, (b) is the bb sectional view taken on the line bb of (a). FIG. (A) is sectional drawing equivalent to FIG. 2 which shows another modification of the guide groove provided in the journal part of the crankshaft of the internal combustion engine of FIG. 1, (b) is bb of (a). It is line sectional drawing. FIG. 5 is a schematic diagram corresponding to FIG. 4, showing another arrangement of the oil passages in the crankshaft of FIG. 1.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Cylinder block, 10 ... Bearing wall, 11 ... Bearing cap, 20 ... Crankshaft, 21-25 ... Journal part, 27 ... Crankpin, 30 ... Guide groove, 40 ... Oil path in shaft, 50 ... Bearing, 53 ... Lubrication groove, 71-75 ... Oil line,
E: Internal combustion engine, S: Seal length.

Claims (2)

An oil supply structure of a crankshaft comprising a bearing to which oil discharged from an oil pump is supplied and a crankshaft having a journal portion supported by the bearing, wherein the journal portion is supplied to a crankpin And an oil passage in the shaft for guiding the oil to be generated, and a guide groove that is opened in the outer peripheral surface of the journal portion while the oil passage in the shaft is open, and oil is supplied to the guide groove on the bearing surface of the bearing. An oil supply groove is provided, and the guide groove extends in a rotation direction of the crankshaft from a portion where the in-shaft oil passage opens.
The oil supply structure for a crankshaft, wherein the oil supply groove and the guide groove are arranged to face each other in a radial direction, and an axial width of the oil supply groove is smaller than an axial width of the guide groove.   The bearing is composed of a first bearing member and a second bearing member that are divided in the circumferential direction, the oil supply groove is provided only in the first bearing member, and the depth of the oil supply groove is determined by the first bearing member. The oil supply structure for a crankshaft according to claim 1, wherein the oil supply structure gradually decreases as it approaches the circumferential end of the crankshaft.

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