JP2004116705A - Supporting structure of crankshaft - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To stably suppress the occurrence of crank hammering noise while avoiding an increase in cost in a crankshaft support structure in which a crankshaft is rotatably pivoted on the crankcase through ball bearings having outer rings fitted to support holes provided in the crankcase. <P>SOLUTION: Bearing energizing means 20 elastically pressing the outer rings 13 to sides for moving the outer rings 13 from the inner surfaces of the support holes 17 are installed in the support hole 17 and between the outer rings 13 and the crankcase 6 at a plurality of circumferentially spaced positions. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a crankshaft support structure in which a crankshaft is rotatably supported on the crankcase via a ball bearing for fitting an outer ring into a support hole provided in the crankcase.
[0002]
[Prior art]
2. Description of the Related Art Conventionally, a crankshaft is rotatably supported by a crankcase via a ball bearing in which an outer ring is fitted into a support hole provided in the crankcase (for example, see Patent Document 1).
[0003]
[Patent Document 1]
JP 2000-345854 A
[Problems to be solved by the invention]
However, on the crankshaft, a force in the direction along the cylinder axis acts due to a piston reciprocatingly sliding within the cylinder bore and an explosion in a combustion chamber facing the top of the piston. The so-called crank striking noise may occur due to the crankshaft being violated by the gap between the outer surface and the inner surface of the support hole. In particular, when the engine is hot, the gap increases due to the difference in the coefficient of thermal expansion between the outer race of the ball bearing and the crankcase, and crank noise is likely to occur.
[0005]
In order to prevent the occurrence of such a crank hitting noise, it is conceivable to press-fit the outer ring of the ball bearing into the support hole of the crankcase. Time, technology and equipment are required for assembly, resulting in increased costs.
[0006]
The present invention has been made in view of such circumstances, and an object of the present invention is to provide a crankshaft support structure capable of stably suppressing the occurrence of crank striking noise while avoiding an increase in cost.
[0007]
[Means for Solving the Problems]
In order to achieve the above object, an invention according to claim 1 is a crankshaft in which the crankshaft is rotatably supported by the crankcase via a ball bearing for fitting an outer ring into a support hole provided in the crankcase. A bearing that elastically presses the outer ring from the inner surface of the supporting hole between the outer ring and the crankcase of the ball bearing at a plurality of locations spaced apart in the circumferential direction of the supporting hole toward the side that separates the outer ring from the inner surface of the supporting hole. It is characterized in that biasing means are provided respectively.
[0008]
According to such a configuration, the position of the ball bearing in a plane orthogonal to the axis of the support hole is elastically pressed by the plurality of bearing urging means provided between the outer ring of the ball bearing and the crankcase. As a result, the engine can be stably maintained from a cold state to a hot state, and the occurrence of crank tapping can be stably suppressed. Moreover, since it is not necessary to press-fit the outer ring of the ball bearing, it is not necessary to significantly increase the processing accuracy of the support hole, and it is possible to avoid an increase in cost.
[0009]
According to a second aspect of the present invention, in addition to the configuration of the first aspect, the plurality of bearing urging means are arranged closer to the cylinder bore than a plane orthogonal to the cylinder axis and including the axis of the crankshaft. According to such a configuration, the plurality of bearing urging means are arranged at positions where the force associated with the explosion in the combustion chamber does not directly act, so that each of the bearing urging means and the ball bearing are disposed. The force applied to the contact portion of the outer ring can be dispersed, and the durability can be improved.
[0010]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described based on embodiments of the present invention shown in the accompanying drawings.
[0011]
1 and 2 show a first embodiment of the present invention. FIG. 1 is a longitudinal sectional view of a main part of an engine, and FIG. 2 is a sectional view taken along line 2-2 of FIG.
[0012]
First, referring to FIG. 1, an engine block 5 provided in the engine integrally includes a cylinder portion 5a having a cylinder bore 8 and a crankcase half portion 5b connected to the cylinder portion 5a. It comprises a case half 5b and a case half 7 coupled to the crankcase half 5b.
[0013]
A piston (not shown) is slidably fitted in the cylinder bore 8, and a crankshaft 11 connected to the piston via a connecting rod 9 and a crankpin 10 is located at a position where the crankpin 10 is interposed therebetween. Are rotatably supported by the crankcase 6 via ball bearings 12 and 12 disposed at the center.
[0014]
2, the ball bearing 12 includes a plurality of balls 15, 15... Of which the circumferential position is regulated by a retainer 16 between an outer ring 13 and an inner ring 14. is there.
[0015]
The inner races 14, 14 of such ball bearings 12, 12 are press-fitted into the inner races 14, 14, thereby defining a position along the axial direction of the crankshaft 11 and relatively moving to the crankshaft 11. Assembled impossible.
[0016]
The crankcase 6 is provided with support holes 17, 17 into which the outer rings 13, 13 of the ball bearings 12, 12 are fitted. The support holes 17,... Are formed by the case half of the crankcase half 5b. 7 and a semicircular concave portion 19 provided on the surface of the case half 7 that is connected to the crankcase half 5b.
[0017]
According to the present invention, the ball bearings 12, 12 are provided between the outer ring 13, 13 of the ball bearings 12, 12 and the crankcase 6 at a plurality of locations, for example, two locations spaced in the circumferential direction of the support holes 17, 17. Bearing biasing means 20, 20,... For elastically pressing the outer ring 13, 13 on the side of separating the outer ring 13 from the inner surface of the support hole 17, 17 are provided, respectively.
[0018]
The bearing urging means 20 includes a wedge 21 slidably fitted to the crankcase 6 such that a pressing surface 21 a at the tip comes into contact with the outer peripheral edge of the outer ring 13 in the ball bearing 12. And a spring 22 for exerting a spring force for pressing the spring 21 toward the outer ring 13.
[0019]
The wedge 21 is formed in a columnar shape, and a pressing surface 21 a is formed at the tip of the wedge 21 so as to be inclined so as to be located axially outward as it goes outward in the axial direction of the support hole 17. The recess 18 on the side of the crankcase half 5b among the recesses 18 and 19 forming the support hole 17 is provided with a slide groove 23 having a semicircular cross section with an outer end opened in the axial direction. Are slidably fitted in the slide groove 23 such that a part thereof projects from the inner surface of the support hole 17.
[0020]
A spring receiving plate 24 facing the rear end of the wedge 21 is fixed to the crankcase half 5b with, for example, a bolt 25, and a spring 22 is contracted between the spring receiving plate 24 and the wedge 21. You.
[0021]
Further, a plurality of, for example, a pair of bearing urging means 20, 20 are arranged on both sides of the cylinder axis C on the side of the cylinder bore 8 with respect to the plane 26 including the axis of the crankshaft 11 perpendicular to the cylinder axis C. That is, the angle α formed by the cylinder axis C and the bearing urging means 20 on the cylinder bore 8 side with respect to the plane 26 is set to 90 degrees or less.
[0022]
Due to such arrangement of the bearing urging means 20, 20,..., The ball bearings 12, 12 and the crankshaft 11 are urged to be offset from the axis of the support hole 17 on the side opposite to the cylinder bore 8. Will be. 1 and 2, the support hole 17 is exaggerated and drawn larger than the ball bearings 12, 12 and the crankshaft 11 for easy understanding.
[0023]
Next, the operation of the first embodiment will be described. The outer rings 13, 13 of the ball bearings 12, 12, which are interposed between the crankshaft 11 and the crankcase 6, are provided with support holes 17, 17 provided in the crankcase 6. The ball bearings 12, 13 of the ball bearings 12, 12 and the crankcase 6 are provided at a plurality of, for example, two, locations spaced apart in the circumferential direction of the support holes 17, 17. There are provided bearing urging means 20, 20... For elastically pressing the outer rings 13, 12 of the twelve sides on the side away from the inner surfaces of the support holes 17, 17, respectively.
[0024]
Therefore, the position of the ball bearings 12, 12 in a plane perpendicular to the axis of the support holes 17, 17 is adjusted by the bearing urging means 20, 20,. It is possible to stably maintain the temperature from cold to hot, so that it is possible to stably suppress the occurrence of crank tapping noise.
[0025]
Moreover, since it is not necessary to press-fit the outer races 13 of the ball bearings 12, 12, it is not necessary to significantly increase the processing accuracy of the support holes 17, and it is possible to avoid an increase in cost.
[0026]
A plurality of, for example, a pair of bearing urging means 20, 20 are arranged on both sides of the cylinder axis C on the side of the cylinder bore 8 with respect to the plane 26 including the axis of the crankshaft 11 perpendicular to the cylinder axis C.
[0027]
Therefore, by arranging a plurality of, for example, a pair of bearing urging means 20, 20 at positions where the force accompanying the explosion in the combustion chamber does not directly act, the respective bearing urging means 20, 20. The force applied to the contact portions 13 and 13 can be dispersed, and the durability can be improved.
[0028]
FIG. 3 shows a second embodiment of the present invention, and portions corresponding to the first embodiment are denoted by the same reference numerals.
[0029]
A bearing that elastically presses the outer ring 13 toward the side that separates the outer ring 13 from the inner surface of the support hole 17 between the outer ring 13 of the ball bearing 12 and the crankcase 6 at a plurality of locations, for example, two locations spaced apart in the circumferential direction of the support hole 17. Biasing means 28, 28 are provided.
[0030]
The bearing urging means 28 includes a pressing pin 29 slidably fitted to the crankcase 6 such that a tip of the outer ring 13 contacts the outer peripheral surface of the outer ring 13 in the ball bearing 12. And a spring 30 that exerts a spring force that presses toward the side.
[0031]
The pressing pin 29 is formed in a cylindrical shape with a closed bottom. In the crankcase half 5b, a bottomed sliding hole 31 having an inner end opening on the inner surface of the concave portion 18 among the concave portions 18 and 19 constituting the supporting hole 17 is provided with an axis extending along the radial direction of the supporting hole 17. The pressing pin 29 is slidably fitted in the sliding hole 31 so that the tip end of the pressing pin 29 protrudes from the inner surface of the support hole 17. A spring 30 is contracted between the end and the pressing pin 29.
[0032]
Further, a plurality of, for example, a pair of bearing urging means 28, 28 are arranged on both sides of the cylinder axis C on the side of the cylinder bore 8 with respect to the plane 26 including the axis of the crankshaft 11 perpendicular to the cylinder axis C. That is, the angle α formed by the cylinder axis C and the bearing urging means 20 on the cylinder bore 8 side with respect to the plane 26 is set to 90 degrees or less.
[0033]
Due to the arrangement of the bearing urging means 28, 28, the ball bearings 12, 12 and the crankshaft 11 are urged to be biased so as to be offset from the axis of the support hole 17 to the side opposite to the cylinder bore 8. become. In FIG. 3, the support holes 17 are exaggerated and drawn larger than the ball bearings 12 and 12 and the crankshaft 11 for easy understanding.
[0034]
According to the second embodiment, the same effects as in the first embodiment can be obtained.
[0035]
Although the embodiments of the present invention have been described above, the present invention is not limited to the above embodiments, and various design changes can be made without departing from the present invention described in the claims. It is.
[0036]
【The invention's effect】
As described above, according to the first aspect of the present invention, the position of the ball bearing in a plane perpendicular to the axis of the support hole is stably maintained from cold to hot in the engine, and the Generation of noise can be suppressed stably, and furthermore, since it is not necessary to press-fit the outer ring of the ball bearing, it is not necessary to significantly increase the processing accuracy of the support hole, and it is possible to avoid an increase in cost.
[0037]
According to the second aspect of the present invention, the plurality of bearing urging means are arranged at positions where the force accompanying the explosion in the combustion chamber does not directly act, so that the contact between each bearing urging means and the outer ring of the ball bearing is achieved. The force applied to the portion can be dispersed, and the durability can be improved.
[Brief description of the drawings]
FIG. 1 is a longitudinal sectional view of a main part of an engine according to a first embodiment.
FIG. 2 is a sectional view taken along line 2-2 of FIG.
FIG. 3 is a cross-sectional view corresponding to FIG. 2 of a second embodiment.
[Explanation of symbols]
6 Crankcase 11 Crankshaft 12 Ball bearing 13 Outer ring 17 Support holes 20, 28 Bearing biasing means 26 Plane C Cylinder axis

Claims (2)

A crankshaft (11) is rotatably supported on the crankcase (6) via a ball bearing (12) for fitting an outer ring (13) into a support hole (17) provided in the crankcase (6). A support structure for a crankshaft, wherein the outer ring (13) is provided between the outer ring (13) of the ball bearing (12) and the crankcase (6) at a plurality of positions spaced in the circumferential direction of the support hole (17). ) Are provided with bearing urging means (20, 28) for resiliently pressing the support holes (17) toward the side away from the inner surface of the support hole (17). A plurality of the bearing urging means (20, 28) are arranged at a position closer to the cylinder bore (8) than a plane (26) orthogonal to the cylinder axis (C) and including the axis of the crankshaft (11). The crankshaft support structure according to claim 1, wherein:

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