JPH0527329U - Oil return device for internal combustion engine - Google Patents

Abstract

(57) [Summary] [Purpose] In an oil return device for an internal combustion engine, effectively suppresses oil splashes that diffuse from around the counterweight. [Structure] A front peripheral end portion 5A located on the front side of rotation of the counterweight 5 is formed by being curved with a larger curvature than a rear peripheral end portion 5B located on the rear side of rotation, and the counterweight outer peripheral end portion is formed on the crankcase inner wall 10A. The drop groove 15 is formed so as to face the rotation trajectory S of 5D and be depressed.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to an improvement of an oil return device for an internal combustion engine.

[0002]

[Prior Art]

 After lubricating the crank journal of the crankshaft, the oil scatters from the high-speed rotating crankshaft into the crank chamber, interferes with the crankshaft, and is delayed in returning to the oil pan.

In order to reduce oil splashes in the crank chamber, there is a conventional one shown in, for example, FIG. 3 (see JP-A-62-220710).

Explaining this, the crankshaft 1 has a shape in which the outer peripheral end portion 21 of the counterweight 5 is thin and has little air resistance. As the crankshaft 1 rotates, the counterweight 5 causes air in the crank chamber and It is designed to prevent stirring of oil droplets. In the figure, 6 is a main bearing, 3 is a crank journal of the crankshaft 1, and 2 is a crankpin.

[0005]

[Problems to be solved by the device]

 However, in such a conventional device, since the tip end portion 21 of the counterweight 5 is tapered in the rotation direction, the oil that collides with the counterweight tip end portion 21 as the crankshaft 1 rotates. The splash was repelled in the direction of the rotation axis and diffused, and the amount of oil splash in the crank chamber could not be sufficiently suppressed.

The present invention focuses on the above points, and an object thereof is to effectively suppress oil splashes that diffuse from around the counterweight of the crankshaft.

[0007]

[Means for Solving the Problems]

 The present invention includes an internal combustion engine that includes a crank journal rotatably supported by a main bearing of an engine body on a crank shaft, a crank pin that connects a connecting rod, and a counter weight that projects from an end of the crank journal in a direction opposite to the crank pin. In the engine, the front peripheral end portion of the counterweight, which is located in front of the rotation, is formed to have a curvature larger than that of the rear peripheral end portion located in the rear of the rotation, and the rotation trajectory of the counterweight outer peripheral end portion is formed on the inner wall of the crankcase. A drop groove is formed facing the surface.

[0008]

[Action]

 Since the front peripheral edge of the counterweight is desired to be curved with a large curved surface, oil droplets that collide with the front peripheral edge as the crankshaft rotates are directed toward the crankcase inner wall located in the outer peripheral direction of the counterweight. It bounces off and the rotational energy lost due to the collision with this oil splash can be kept small.

As a result, the oil splashes that are splashed back in the outer peripheral direction of the counterweight spread along the locus of the outer peripheral edge of the counterweight, and are collected in the drop groove that is located on this extension on the crankcase inner wall, It is quickly returned to the oil pan through the. As a result, the oil splash that diffuses into the crankcase is reduced, and friction is reduced.

[0010]

【Example】

 Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings.

As shown in FIGS. 1 and 2, the crankshaft 1 includes a crank pin 2 that supports a connecting rod, a crank journal 3 that is supported by a main bearing 6 provided on the engine body side, and a crank pin 2. It has a crank web 4 that connects the crank journal 3 to each other, and a counter weight 5 that adds a predetermined mass to a position facing the crank web 4 with the center of rotation of the crank shaft 1 interposed therebetween.

In FIG. 1, the crankshaft 1 rotates in the clockwise direction as shown by the arrow, but the peripheral end portion of the counterweight 5 is located at the front side of the rotation, and is curved forward with a relatively large curvature. It has an end portion 5A and a rear peripheral end portion 5B located at the rear of the rotation and curved with a relatively small curvature. In FIG. 1, the center line C is a line segment passing through the center of the crank journal 3 and the center of the crank pin 2, but the center line C intersects with the middle of the front peripheral end portion 5A. Therefore, the crank web 4 is formed symmetrically with respect to the center line C, while the counterweight 5 is formed asymmetrically.

The front peripheral end portion 5A of the counterweight 5 is a curved surface that continuously extends from the planar peripheral end portion 4A of the crank web 4 and its cross section is formed parallel to the rotation axis.

The counterweight 5 has a flat peripheral edge 5C continuously extending from the flat peripheral edge 4A of the crank web 4, and the rear peripheral edge 5B has a flat peripheral edge 5C and a front peripheral edge. The portion 5A is connected by a curved surface. In FIG. 1, 5D is an outer peripheral end where the front peripheral end 5A and the rear peripheral end 5B intersect, and this outer peripheral end 5D is the part farthest from the rotation center of the counterweight 5 of the crank journal 3.

On the other hand, the crankcase 10 is composed of a skirt portion 12 that extends to a lower portion of the cylinder block 11, and a side wall portion 14 of an oil pan 13 that is coupled to a lower end of the skirt portion 12 and stores oil. The inner wall 10A of the crankcase 10 is formed in an arc-shaped cross section with a predetermined gap with respect to the arc S which is the locus of the outer peripheral end 5D of the counterweight 5. A drop groove 15 is formed which is located at. The drop groove 15 is formed so as to face an arc S which is a locus of the outer peripheral end portion 5D of the counterweight 5, and extends in an arc shape across the skirt portion 12 of the cylinder block 11 and the side wall portion 14 of the oil pan 13. ing. The drop groove 15 is recessed in an arcuate cross section, and its opening width is formed larger than the width of the counterweight 5 (thickness in the rotation axis direction).

Next, the operation will be described.

During engine operation, the crankshaft 1 converts the reciprocating motion of the piston into the continuous rotary motion of the crankshaft 1 via the connecting rod.

Since the front peripheral end portion 5A of the counterweight 5 is curved and formed with a large curved surface, oil splashes that collide with the front peripheral end portion 5A as the crankshaft 1 rotates are directed in the outer peripheral direction of the counterweight 5. It bounces back (in the radial direction relative to the axis of rotation), and the rotational energy lost due to the collision with this oil droplet can be suppressed to a small level.

As a result, the oil splashes that are splashed back in the outer peripheral direction of the counterweight 5 spread along the trajectory S of the counterweight outer peripheral end 5D, and the drop groove 15 that is recessed on the crankcase inner wall 10A is located on this extension. Collected in. Since the drop groove 15 is recessed with an arcuate section, the oil that collides with the drop groove 15 is collected without returning to the crank chamber and is quickly returned to the oil pan 13 through each drop groove 15. As a result, oil splashes that diffuse into the crankcase are reduced, and friction is reduced.

Further, as the crankshaft 1 rotates, the lubricated oil flowing out from the sliding contact portion between the crank journal 3 and the main bearing 6 runs along the front and rear end faces 5E and 5F of the crank web 4 and the counter weight 5. The scattered oil is scattered in the outer peripheral direction of the counterweight 5, and the discharged oil is also collected in the drop groove 15 which is located on the extension of the counterweight 5 and is quickly returned to the oil pan.

[0021]

[Effect of the device]

 As described above, in the present invention, in the oil return device for an internal combustion engine, the front peripheral end portion of the counterweight located in front of rotation is formed with a larger curvature than the rear peripheral end portion located in rear of rotation. In addition, since the drop groove is formed on the inner wall of the crankcase so as to face the rotation track of the outer peripheral end of the counterweight, oil droplets in the crankcase are prevented from interfering with the counterweight and spreading. It has the effect of reducing friction during rotation.

[Brief description of drawings]

FIG. 1 is a front view of an apparatus showing an embodiment of the present invention.

FIG. 2 is a plan view of the same device.

FIG. 3 is a plan view of a crankshaft showing a conventional example.

[Explanation of symbols]

 1 Crank Shaft 2 Crank Pin 3 Crank Journal 4 Crank Web 5 Counterweight 5A Front Edge 5B Rear Edge 5D Outer Edge 10 Crank Case 15 Drop Groove

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Kenshi Ushijima 2 Takara-cho, Kanagawa-ku, Yokohama-shi, Kanagawa Nissan Motor Co., Ltd.

Claims (1)

[Scope of utility model registration request] 1. An internal combustion engine comprising a crank journal rotatably supported by a main bearing of an engine main body on a crank shaft, a crank pin connecting a connecting rod, and a counterweight projecting from an end of the crank journal in a direction opposite to the crank pin. In the engine, the front peripheral end portion of the counterweight which is located in front of the rotation is formed to have a curvature larger than that of the rear peripheral end portion which is located in the rear of rotation, and is formed on the inner wall of the crankcase. An oil return device for an internal combustion engine, characterized in that a drop groove which is recessed facing the above is formed.