JPH062708A - Oil retaining structure of crankshaft - Google Patents

Abstract

PURPOSE:To previously prevent the break of an oil film by retaining the oil in sliding parts from flowing in the axial direction, so that oil can be sufficiently retained in the sliding parts. CONSTITUTION:A crank journal 2 is rotatably supported by a cylinder block 6 via crankshaft bearings 7, 8, and the large end part 10 of a connecting rod 9 is connected to a crankpin 3 via connecting rod bearings 11, 12. The oil passage 16 that has been provided inside a crankshaft C is opened to the outer circumferential surface of the crank journal 2 and to the outer circumferential surface of the crankpin 3 respectively. Further, pairs of oil-retaining entire circumferential grooves 20, 21 are provided to both the axial end parts of the outer circumferential surface of the crankpin 3 and to both the axial end parts of the outer circumferential surface of the crank journal 2 respectively.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an oil holding structure for holding lubricating oil supplied between an engine crankshaft and a bearing.

[0002]

2. Description of the Related Art Conventionally, for example, Japanese Utility Model Laid-Open No. 62-13222 discloses a technique in which an oil film is held between a crankpin of a crankshaft and a bearing, and foreign substances mixed in the oil film are removed to the outside of the bearing. Is disclosed. This technique focuses on the fact that a vertically divided metal is used as the bearing of the connecting rod. For details, as shown in FIG.
The crank pin 32 of the crank shaft 31 is connected to the connecting rod 3 via a pair of upper and lower metals 33 and 34.
The large ends 36 of 5 are connected. Each metal 33, 34
Has a semicircular shape, and an oil groove 37 extending in the circumferential direction is formed on the inner peripheral surface of the metal 34 having a smaller bearing load (lower side in FIG. 3).
Are formed. The oil groove 37 communicates with an oil passage 38 that opens to the crank pin 32, and also communicates with a gap formed in at least one of the joint portions 39 of the two metals 33 and 34.

According to this technique, both upper and lower metal 33, 3
The increase in pressure applied to 4 is suppressed as much as possible. Further, the oil film is stably held by the oil supplied to the oil groove 37 through the oil passage 38. Further, the oil is discharged to the outside through the gap between the joints 39 between the upper and lower metals 33, 34. Therefore, the foreign matter mixed in the oil film can be removed as the oil flows.

[0004]

In the above-mentioned conventional technique, the oil film can be stably held between the oil groove 37 and the crank pin 32, and the lubrication at the same portion can be guaranteed. However, in the sliding parts between the upper and lower metal parts 33 and 34 and the crank pin 32, the oil in the parts other than the oil groove 37 is absorbed by the axis L3.
It tends to flow in the direction and flow out from both ends of the sliding part. For this reason, the oil film cannot be sufficiently held in the sliding portion, and the oil film may run out.

The present invention has been made in view of the above-mentioned circumstances, and an object thereof is to suppress the oil in the sliding portion from flowing in the axial direction and sufficiently hold the oil in the sliding portion to form an oil film. An object of the present invention is to provide a crankshaft oil holding structure capable of preventing breakage.

[0006]

In order to achieve the above-mentioned object, the present invention supports a crank journal of a crankshaft rotatably on a cylinder block of an engine through a crankshaft bearing, and a crank of the crankshaft. The large end of the connecting rod is connected to the pin via a connecting rod bearing, and the oil passages provided in the crankshaft are opened to the outer peripheral surface of the crank journal and the outer peripheral surface of the crankpin, respectively. A pair of axial outer ends of the journal outer surface and the crankshaft bearing inner circumferential surface, and a pair of axial outer ends of the crankpin and connecting rod bearing inner axial surfaces, respectively. A full-circumferential groove for oil retention is provided.

[0007]

When the crankshaft rotates, the oil passing through the oil passage is supplied to the sliding portion between the crank journal and the crankshaft bearing and the sliding portion between the crankpin and the connecting rod bearing to form an oil film. It The formation of this oil film reduces the frictional resistance in the sliding portion.

When the crankshaft rotates, the oil forming the oil film tends to flow in the axial direction. Due to this flow, there is a possibility that the amount of oil at the axially opposite ends of the sliding portion will decrease. However, a pair of all-round grooves for holding oil are provided at both ends in the axial direction of the outer peripheral surface of the crank journal or the inner peripheral surface of the crankshaft bearing. In addition, a pair of all-round grooves for holding oil are provided at both ends of the outer peripheral surface of the crank pin or the inner peripheral surface of the connecting rod bearing in the axial direction. Oil in these circumferential grooves and in the vicinity thereof serves as a resistance against the oil flow in the axial direction. Therefore, as described above, the flow of oil, which tends to flow in the axial direction, is temporarily weakened in the circumferential groove portion, and is less likely to flow outside than the circumferential groove. As a result, oil is retained in the sliding portion between the two circumferential grooves.

Further, there is no need for a portion for preventing oil outflow on both ends of the sliding portion in the axial direction. Furthermore, since the oil film breakage due to the oil spill is reduced,
The amount of oil supplied to the sliding parts is small.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment embodying the present invention will be described below with reference to FIG. FIG. 1 is an enlarged sectional view showing a part of a crankshaft C assembled in an engine.
The crankshaft C is for converting reciprocating motion of the piston into rotary motion and taking out power. The crankshaft C includes a cylindrical crank journal 2 and
The crank journal 2 is provided with a cylindrical crank pin 3 arranged in parallel to the axis L1 of the crank journal 2, a crank arm 1 connecting the two crankshafts 2 and 3, and a counterweight 4 for balancing rotation.

The crank journal 2 is rotatably attached to a cylinder block 6 of the engine by a bearing cap 5. That is, semicircular crankshaft bearings 7 and 8 are locked to the cylinder block 6 and the bearing cap 5, respectively, and these are fitted onto the crank journal 2.

A large end 10 of a connecting rod 9 is rotatably connected to the crank pin 3.
That is, a pair of upper and lower connecting rod bearings 11 and 12 having a semicircular shape are locked to the large end portion 10, and these are fitted onto the crank pin 3. A step portion 13 is integrally formed on each of the crank arms 1 on both ends of the crank pin 3. Both step parts 13 are crank pins 3
This is for receiving the stress of the connecting rod 9 acting in the direction of the axis L2.

In order to form an oil film between the outer peripheral surface of the crank journal 2 and the inner peripheral surfaces of the upper and lower crankshaft bearings 7 and 8 for lubrication, the cylinder block 6 is provided.
An oil passage 14 is provided in the. Oil passage 14
Communicates with a through hole 15 provided through the upper crankshaft bearing 7. Therefore, the oil pressure-fed to the oil passage 14 by the oil pump (not shown) passes through the through hole 15 and enters the gap between the outer peripheral surface of the crank journal 2 and the inner peripheral surfaces of the upper and lower crankshaft bearings 7, 8. Supplied.

An oil passage 16 is provided inside the crankshaft C in order to form an oil film between the outer peripheral surface of the crankpin 3 and the inner peripheral surfaces of the upper and lower connecting rod bearings 11 and 12 for lubrication. Has been. The oil passage 16 communicates with the first oil hole 17 orthogonal to the axis L1 of the crank journal 2, the second oil hole 18 orthogonal to the axis L2 of the crankpin 3, and the two oil holes 17, 18. And holes 19. Both ends of the first oil hole 17 are open at the center of the outer peripheral surface of the crank journal 2. Further, both ends of the second oil hole 18 are opened at the center of the outer peripheral surface of the crankpin 3. Therefore, a part of the oil supplied between the outer peripheral surface of the crank journal 2 and the inner peripheral surfaces of the upper and lower crankshaft bearings 7, 8 is part of the first oil hole 17, the communicating hole 19, and the second hole.
Through the oil hole 18 of the crank pin 3 and the inner peripheral surfaces of the upper and lower connecting rod bearings 11 and 12.

Further, a pair of full circumferential grooves 20 having a semicircular cross section are provided at both ends of the outer peripheral surface of the crank journal 2 in the direction of the axis L1. Similarly, a pair of full-circumferential grooves 21 having a semicircular cross section are provided at both ends of the outer peripheral surface of the crankpin 3 in the direction of the axis L2.

Next, the operation and effect of this embodiment constructed as described above will be explained. When the crankshaft C is rotated, the oil passage 1 is provided in the sliding portion between the crank journal 2 and the upper and lower crankshaft bearings 7 and 8.
The oil is supplied via 4 and the through hole 15 to form an oil film. Further, the first oil hole 1 is provided in the sliding portion between the crank pin 3 and the upper and lower connecting rod bearings 11 and 12.
The oil that has passed through 7, the communication hole 19 and the second oil hole 18 is guided to form an oil film. The formation of these oil films reduces the frictional resistance in the sliding portion.

When the crankshaft C rotates, the oil forming the oil film tends to flow in the axis L1 direction and the axis L2 direction, respectively. Due to this flow, there is a risk that the oil in the sliding portion at both ends in the axis L1 direction and at the ends in the axis L2 direction will decrease. However, in the present embodiment, a pair of all-round grooves 20 are provided on both ends of the crank journal 2 in the axial direction L1 and a pair of all-round grooves 21 are provided on both ends of the crank pin 3 in the axial direction L2. It is provided. The oil in these circumferential grooves 20, 21 and in the vicinity thereof serves as a resistance to the flow of oil in the direction of the axis L1 and the direction of the axis L2. Therefore, the flow of the oil is temporarily weakened in the circumferential groove portions 20 and 21, and the oil flows in the circumferential groove portions 2 and 2.
It becomes more difficult to flow outside than 0 and 21. As a result, oil is retained in the sliding portion between the two circumferential grooves 20 and 21, and the oil film breakage at the same location is eliminated.

By the way, in the above-mentioned prior art, the oil in the sliding portion between the crank pin 32 and the upper and lower metal parts 33 and 34 is likely to flow out from both ends in the direction of the axis L3 to cause seizure. It is necessary to prevent the oil from flowing out. For example, as shown by the chain double-dashed line in FIG. 1, the wall thickness of the large end portion 10 of the connecting rod 9 is increased. Further, the step portions 13 on both end sides of the crank pin 3 can be brought into contact with both end surfaces of the large end portion 10,
Swell to the piston side (upward in Fig. 1). Then, it is considered that the both ends of the large end portion 10 are always brought into contact with the inner wall surface of the step portion 13 to prevent the oil from flowing out.

On the other hand, in this embodiment, since the oil flow is weakened by the pair of circumferential grooves 20 and 21 as described above, it is not necessary to always bring the large end portion 10 and the step portion 13 into contact with each other. . Therefore, as shown by the solid line in FIG. 1, the large end portion 10 of the connecting rod 9 can be made thin, and the bulging portion of the stepped portion 13 can be removed. Since the balance of the rotation of the crankshaft C is changed due to this meat removal, if an attempt is made to keep the balance ratio constant, a part of the counterweight 4 (A and B in FIG. 1) will be used.
Part) will be removed. Therefore, by removing these thicknesses, the crankshaft C can be made significantly lighter than before,
The rotating mass can be reduced.

Further, in the above-mentioned prior art, as a measure for eliminating the oil film shortage due to the oil outflow, it is conceivable to supply a large amount of oil to compensate for the oil shortage due to the oil outflow. On the other hand, in this embodiment, the oil outflow is reduced by the circumferential grooves 20 and 21, so that the amount of oil supplied to the sliding portion can be reduced accordingly. Accordingly, the oil pump can be downsized.

The present invention is not limited to the configuration of the above-mentioned embodiment, and may be arbitrarily modified within the scope not departing from the spirit of the invention as follows, for example. (1) Instead of the outer peripheral surface of the crank journal 2, as shown in FIG. 2, both upper and lower crankshaft bearings 7, 8
The entire circumferential groove 20 may be provided at both ends of the inner circumferential surface of the. Also,
Although not shown, instead of the outer peripheral surface of the crank pin 3, the entire circumferential grooves 21 may be provided at both ends of the inner peripheral surfaces of the upper and lower connecting rod bearings 11 and 12. Even in this case, the same operation and effect as those of the above-described embodiment can be obtained. (2) The cross-sectional shape of the circumferential grooves 20, 21 may be appropriately changed to a shape other than a semicircle, for example, a quadrangle, a triangle, or a semi-elliptical shape.

[0022]

As described above in detail, according to the present invention, either one of the outer peripheral surface of the crank journal and the inner peripheral surface of the crankshaft bearing in the axial direction, and the outer peripheral surface of the crank pin and the connecting rod bearing. Since a pair of full-circumferential grooves for oil retention are provided on both ends of the inner peripheral surface in the axial direction, the flow of oil in the axial direction at the sliding parts is suppressed, and both full-circumferential grooves are suppressed. Sufficient oil can be retained between them to prevent oil film breakage. Along with this, there is no need for a portion for preventing oil outflow on both sides in the axial direction of the sliding portion, and the weight of the crankshaft can be reduced and the rotational mass of the crankshaft can be reduced accordingly. Furthermore, since the oil film breakage due to the oil outflow is reduced, it is possible to reduce the amount of oil supplied to the sliding portion.

[Brief description of drawings]

FIG. 1 is a partial cross-sectional view showing an oil holding structure for a crankshaft according to an embodiment of the present invention.

FIG. 2 is a cross-sectional view showing another example in which an entire circumferential groove is provided on the inner peripheral surface of a crankshaft bearing.

FIG. 3 is a partial cross-sectional view showing a conventional crankshaft oil holding structure.

[Explanation of symbols]

2 ... crank journal, 3 ... crank pin, 6 ... cylinder block, 7, 8 ... crankshaft bearing,
9 ... Connecting rod, 10 ... Large end, 11, 12
... connecting rod bearing, 16 ... oil passage, 20, 2
1 ... All-round groove, C ... Crank shaft, L1, L2 ... Axis

Claims (1)

[Claims] 1. A cylinder block of an engine rotatably supports a crank journal of a crankshaft through a crankshaft bearing, and a crankpin of the crankshaft is provided with a large end portion of a connecting rod through a connecting rod bearing. Oil passages that are connected to each other and are provided in the crankshaft are opened to the outer peripheral surface of the crank journal and the outer peripheral surface of the crankpin, respectively, and further, one of the outer peripheral surface of the crank journal and the inner peripheral surface of the crankshaft bearing. A pair of full-circumferential grooves for oil retention are provided at both axial end portions and at both axial end portions of one of the outer peripheral surface of the crank pin and the inner peripheral surface of the connecting rod bearing. Crankshaft oil holding structure.