Title of Invention

"BEARING STRUCTURE FOR CRANKSHAFT IN INTERNAL COMBUSTION ENGINE"

Abstract

A bearing structure for crankshaft in internal combustion engine, comprising a crankshaft (6) rotatably supported on a crankcase (10) through rolling bearing (BB), a backlash generated in the radial direction between an outer race (23) of said rolling bearing (BB), and a bearing hole (18) in said crankcase (10) being absorbed by a backlash absorb mechanism (A) provided between said outer race (23) of said rolling bearing (BB) and said crankcase (10), wherein said backlash absorbing mechanism (A) is provided with a push plug (30) which has an slant surface (30s) and pushes an outer circumferential surface of the outer race (23) to an inward direction of the crankshaft (6) by a pushing force (F), the backlash absorbing mechanism (A) absorbs said backlash according to a radial direction of the crankshaft (6) by a component force (Fr) of the pushing force (F), a movement restraining member (40) for restraining said outer race (23) moving to the inward direction of the crankshaft (6) by the pushing force (F) of the push plug (30) is engaged with the outer race (23), the movement restraining member (40) is fixed by a bolt (43) to an outside surface of a crankcase (10), the movement restraining member (40) and a bolt (43) are shifted to a circumferential direction of a crankshaft (6) from said backlash absorbing mechanism (A), and the movement restraining member (A) is arranged the inward direction of the crankshaft (10) rather than an outer surface of the backlash absorbing mechanism (A). Fig. 9

Full Text

[Name of Document] Specification [Title of the Invention] Bearing Structure for Crankshaft in Internal Combustion Engine [Technical Field] [0001] The present invention relates to a bearing structure for rotatably supporting a crankshaft on a crankcase in an internal combustion engine. [Background Art] [0002] Generally, in a single-cylinder internal combustion engine for a motorcycle or the like, a crankshaft is rotatably shaft-supported on a crankcase through a left-right pair of rolling bearings, a piston slidable in a cylinder bore is connected to a crank pin of the crankshaft through a connecting rod, and an explosion pressure exerted on the piston is transmitted from the crankshaft to be received by the crankcase through the pair of rolling bearings. In this case, it is desirable that outer races and inner races of the pair of rolling bearings are respectively press fitted in or over bearing portions of the crankcase and journal shaft portions of the crankshaft, whereby a rattling sound due to backlashes between the fitted components is prevented from being generated, and a desired bearing function for the crankshaft is maintained, thereby securing smooth and light rotation. [0003] With such a configuration, however, if the left and right rolling bearings are pressed fitted in or over both the crankshaft and the crankcase, it is difficult to mount the crankshaft onto the crankcase and to subsequently perform maintenance thereof. [0004] In order to solve this problem, conventionally, there has been adopted a structure in which, as shown in Fig. 9, at the time of mounting the crankshaft onto the crankcase, the outer race of the right-side rolling bearing is press fitted into a right-side crankcase half and the inner race of the left-side rolling bearing is press fitted over a left-side journal shaft portion of the crankshaft prior to mounting the crankshaft onto the crankcase, and, at the time of mounting the crankshaft, a right-side journal shaft portion of the crankshaft is press fitted in the inner race of the right-side rolling bearing (of which the outer race is already press fitted in the right-side crankcase half), and then the outer race of the left-side rolling bearing, with the inner race thereof already press fitted over the left-side journal portion of the crankshaft, is play fitted (fitted, with a play) into a left-side crankcase half, thereby facilitating the mounting of the crankshaft onto the crankcase and the maintenance thereof. [0005] In such a structure, however, a little "backlash" is unavoidably generated between the outer race of the left-side rolling bearing and a bearing surface of the crankcase, and, therefore, a rattling sound due to the "backlash" is generated upon the operation of the internal combustion engine, and the desired bearing function cannot be obtained. [0006] In view of this problem. Patent Document 1 proposes a structure in which the outside surface of the outer race of either one (the left-side one) of a pair of ball bearings is pushed in the axial direction by a push plug having an inclined push surface so as to absorb the "backlash". In this structure, however, the pushing force exerted on the outer race by the push plug is divided into a component force in the radial direction (for absorbing the "backlash") and a component force in the axial direction, with the result that the component force in the axial direction acts as a force for moving the outer race in the axial direction. [0007] Meanwhile, in the structure disclosed in Patent Document 1, the ball bearing (in which a resistance force for receiving the force in the axial direction is present) is adopted for each of the left-right pair of rolling bearings for the crankshaft, so that the component force in the axial direction generated by the pushing force from the push plug can be satisfactorily received by the ball bearing (the right-side ball bearing) on the side of not being pushed by the push plug, and the shifting of the bearing due to the component force in the axial direction can be precluded. [Patent Document 1] Japanese Patent Laid-Open No. 2003-83080 [Disclosure of the Invention] [Problems to Be Solved by the Invention] [0008] However, the ball bearing is bulkier in the radial direction than the roller bearing and the needle bearing, in comparison for the same rated capacity, leading to a larger occupying space of the crankshaft in the radial direction and, hence, to an increase in the overall size of the internal combustion engine and to an increase in weight. Therefore, there is a demand for adopting a bearing other than the ball bearing, for example, the roller bearing or the needle bearing smaller in diameter and higher in rigidity, as at least one of the bearings for bearing the crankshaft. [0009] The present invention has been made in consideration of the above-mentioned circumstances. Accordingly, it is an object of the present invention to provide a bearing structure for crankshaft in internal combustion engine, including a rolling bearing provided with a means for absorbing a backlash in the radial direction, wherein a bearing other than the ball bearing, for example, a small-sized lightweight roller bearing or needle bearing or the like can be used as at least one of the rolling bearings for bearing the crankshaft. [Means for Solving the Problems] [0010] In order to attain the above object, the invention as set forth in claim 1 provides a bearing structure for crankshaft in internal combustion engine, including a crankshaft rotatably supported on a crankcase through rolling bearings, a backlash generated in the radial direction between an outer race of the rolling bearing and a bearing hole in the crankcase being absorbed by a backlash absorbing means provided between the outer race of the rolling bearing and the crankcase, characterized in that a movement restraining means for restraining the outer race of the rolling bearing provided with the backlash absorbing means from moving in the axial direction is provided between the outer race and the crankcase. [0011] In addition, the invention as set forth in claim 2 is characterized, in addition to the characteristic as set forth in claim 1, in that a plurality of the movement restraining means are disposed at intervals along the circumferential direction of the outer race. [0012] Further, the invention as set forth in claim 3 is characterized, in addition to the characteristic as set forth in claim 1 or 2, in that the movement restraining means includes an engaging groove provided in the inner circumferential surface of the outer race, and a movement restraining member provided on the outside surface of the crankcase, and a hook portion of the movement restraining member is engaged with the engaging groove. [Effects of the Invention] [0013] According to the first characteristic of the invention as set forth in claim 1, the "backlash" in the radial direction generated between the outer race of the rolling bearing for rotatably bearing the crankshaft and the bearing hole therefor is absorbed by the "backlash absorbing means", whereby rattling sounds due to the "backlash" can be prevented from being generated, and a desired bearing function can be maintained. In addition, the movement in the axial direction of the outer race of the rolling bearing which necessarily arises from the presence of the "backlash absorbing means" can be restrained by the "movement restraining means", so that a roller bearing, a needle bearing or the like more inexpensive, lighter in weight and more compact than the ball bearing can be used as the rolling bearing for bearing the crankshaft. [0014] Besides, according to the second characteristic of the invention as set forth in claim 2, in addition to the first characteristic, the rolling bearing can be prevented from falling down by the plurality of the"movement restraining means". [0015] Furthermore, according to the third characteristic of the invention as set forth in claim 3, in addition to the first or second characteristic, the "movement restraining means' can be easily mounted from the outside of the crankcase half, and it is unnecessary to provide the crankcase with a cutout or relief for mounting a moving means onto a bearing surface, so that the strength of the crankcase is prevented from being spoiled. The present invention relates to a bearing structure for crankshaft in internal combustion engine a bearing structure for crankshaft in internal combustion engine, comprising a crankshaft (6) rotatably supported on a crankcase (10) through rolling bearing (BB), a backlash generated in the radial direction between an outer race (23) of said rolling bearing (BB), and a bearing hole (18) in said crankcase (10) being absorbed by a backlash absorb mechanism (A) provided between said outer race (23) of said rolling bearing (BB) and said crankcase (10), wherein said backlash absorbing mechanism (A) is provided with a push plug (30) which has an slant surface (30s) and pushes an outer circumferential surface of the outer race (23) to an inward direction of the crankshaft (6) by a pushing force (F), the backlash absorbing mechanism (A) absorbs said backlash according to a radial direction of the crankshaft (6) by a component force (Fr) of the pushing force (F), a movement restraining member (40) for restraining said outer race (23) moving to the inward direction of the crankshaft (6) by the pushing force (F) of the push plug (30) is engaged with the outer race (23), the movement restraining member (40) is fixed by a bolt (43) to an outside surface of a crankcase (10), the movement restraining member (40) and a bolt (43) are shifted to a circumferential direction of a crankshaft (6) from said backlash absorbing mechanism (A), and the movement restraining member (A) is arranged the inward direction of the crankshaft (10) rather than an outer surface of the backlash absorbing mechanism (A). [Best Mode for carrying out the Invention] [0016] Now, a mode for carrying out the present invention will be described specifically below, based an embodiment of the present invention illustrated in the accompanying drawing. [Brief Description of the Drawings] [0038] [Fig. 1] Fig. 1 is a vertically sectional side view of an essential part of an internal combustion engine including a bearing structure for crankshaft according to the present invention. [Fig. 2] Fig. 2 is a sectional view along line 2-2 of Fig. 1 [Fig. 3] Fig. 3 is an enlarged sectional view along line 3-3 of Fig. 1. [Fig. 4] Fig. 4 is a sectional view along line 4-4 of Fig. 3, [Fig. 5] Fig. 5 is an enlarged sectional view along line 5-5 of Fig. 3. [Fig. 6] Fig. 6 is a perspective view of a push plug. [Fig. 7] Fig. 7 is a perspective view of a movement restraining member. [Fig. 8] Fig. 8 is a functional diagram showing the condition at the time of mounting a backlash absorbing means. [Fig. 9] • Fig. 9 is a diagram illustrating the process of mounting a crankshaft onto a crankcase. [0017] In the accompanying drawings. Fig. 1 is a vertically sectional side view of an essential part of an internal combustion engine including a bearing structure for crankshaft according to the present invention; Fig. 2 is a sectional view along line 2-2 of Fig. 1; Fig. 3 .-is an enlarged sectional view along line 3-3 of Fig. 1; Fig. 4 is a sectional view along line 4-4 of Fig. 3; Fig. 5 is an enlarged sectional view along line 5-5 of Fig. 3; Fig. 6 is a perspective view of a backlash absorbing means; Fig. 7 is a perspective view of a movement restraining means; and Fig. 8 is a functional diagram for illustrating the condition at the time of mounting the backlash absorbing means. [0018] First, in Figs. 1 and 2, an OHC type four-cycle single-cylinder internal combustion engine E includes a cylinder block CB, a cylinder head CH fixed onto a deck surface of the cylinder block CB, a left-right split crankcase CC fixed to a lower portion of the cylinder head CH, and a head cover HC attached to an upper surface of the cylinder head CH, wherein a piston 3 is slidably fitted in a cylinder 1 provided in a central portion of the cylinder block CB and having a cylinder sleeve 2, and a combustion chamber 4 is formed in the cylinder head CH oppositely to the top surface of the piston 3. A small end portion of a connecting rod 5 is rotatably connected to a piston pin of the piston 3, and a large end portion of the connecting rod 5 is rotatably connected to a crank pin 7 of the crankshaft 6. A crankshaft 6 is rotatably supported on the crankcase CC through left and right rolling bearings BE, BR which will be described later. [0019] The crankcase CC is composed of left-side crankcase half 10 and a right-side crankcase half 11 which are cast from iron or a light alloy based on aluminum or the like and are integrally coupled to each other by a plurality of bolts 14. A left-side cover 12 is attached to the outside surface of an opening of the left-side crankcase half 10 and fixed in situ by a bolt 15, whereas a right-side cover 13 is attached to the outside surface of an opening of the right-side crankcase half 11 and fixed in situ by a bolt 16. The left-side and right-side crankcase halves 10 and 11 are integrally provided respectively with left and right journal walls 10j and 11j which are opposed to each other with an interval therebetween, the left and right journal walls 10j and 11j are provided respectively with left and right bearing holes 18 and 19 (the left bearing hole 18 is larger in diameter than the right bearing hole 19) opened on the same axis, and bearing surfaces of the left and right bearing holes 18, 19 are each formed of an Fe-made cast ring which is cast at the time of casting the crankcase. Left and right journal shaft portions 6jl, 6jr of the crankshaft 6 are rotatably borne on the left and right bearing holes 18, 19 through the left-side and right-side rolling bearings BB, BR. As clearly shown in Fig. 4, the left-side rolling bearing BB is composed of a ball bearing, whereas the right-side rolling bearing BR is composed of a roller bearing. An inner race 22 of the left-side rolling bearing, or ball bearing, BB is press fitted over the left journal shaft portion 6jl of the crankshaft 6, and an outer race 23 thereof is play fitted (with some backlash in the radial direction) in the bearing hole 18 in the left journal wall 10j. The outer race 23 of the ball bearing BB is extended to the outer side in the axial direction (away from the cylinder axis) relative to the inner race 22 of the ball bearing BB, and the inner circumferential surface of the extended portion 23e is provided with an engaging groove 41 recessed in section which constitutes a "movement restraining means S" described later, and a hook portion 40f of a movement restraining member 4 0 is disengageably engaged with the engaging groove 41. As shown in Fig. 4, a gap is provided between the engaging groove 41 and the hook portion 4Of so as to permit the outer race 23 to slightly move in the axial direction relative to the hook portion 40f. [0020] In addition, an inner race 26 of the right-side rolling bearing, or roller bearing, BR is fitted over the right journal shaft portion 6jr of the crankshaft 6, and an outer race 27 of the roller bearing BR is press fitted in the bearing hole 19 in the right journal wall 11j. [0021] Incidentally, after the inner race 26 is fitted over the right journal shaft portion 6jr of the crankshaft 6, the fixation of the inner race 26 onto the right journal shaft portion 6jr of the crankshaft 6 is conducted by co-fastening it by a nut from a shaft end of the crankshaft 6 together with a gear group 62 and a centrifugal filter 63 (see Fig. 1). As shown in Figs. 1 and 3, between the crankshaft 6 and the cylinder 1, a "backlash absorbing means A" for absorbing the "backlash" in the radial direction between the outer race 23 of the ball bearing BE and the bearing hole 18 is provided on the left journal wall 10j of the left-side crankcase half 10 at a position close to the outside of an upper portion of the ball bearing BB and along the axial direction of the crankshaft 6. [0022] As shown in Figs. 3, 4 and 6, the "backlash absorbing means A" is composed of a push plug 30, a coil spring 31, and a spring set plate 32. The push plug 30 is formed in a bottomed hollow cylindrical shape, and is provided with a slant surface 3 0s at a corner portion of the bottom side end wall thereof. The push plug 30 is slidably fitted in a cylindrical hole 35 which is formed in a boss portion 34 on the skewly upper side of the ball bearing BB of the left journal wall 10j and which has an axis in the axial direction of the crankshaft 6 (the direction orthogonal to the cylinder axis). [0023] As shown in Fig. 4, a corner portion 23c arcuate in section of the outer race 23 of the ball bearing BB projects into the cylindrical hole 35, and the slant surface 3 0s of the push plug 3 0 abuts on the corner portion 23c. The coil spring 31 is contained in the push plug 30, and the outer end thereof protrudes to the outside beyond the opening end surface of the push plug 30. The spring set plate 32 is formed to be slender and elongate in the radial direction of the crankshaft 6, and is composed of a base portion 32b provided with a bolt hole 33, an intermediate portion 32n provided with a spring-receiving recessed portion d in the inside surface thereof, and a free end portion 32f having a bent portion b bent inwards. The base portion 32b is bolted to the outside surface of the left-side crankcase half 10 by a mount bolt 38, the spring-receiving recessed portion d of the intermediate portion 32n receives the outer end of the coil spring 31, and the free end portion 32f having the bent portion b is engaged with a positioning portion 36 formed to be smaller in width than the intermediate portion 32n, formed as one body with the left-side crankcase half, being folding fan-shaped in side view (see Fig. 2) and being fork-shaped in section (see Fig. 5), whereby the spring set plate 32 is positioned in the state of being prevented from rotating. [0024] In mounting the "backlash absorbing means A" onto the left-side crankcase half 10, as shown in Fig. 8, the spring set plate 32 is loosely tentatively fixed to the left-side crankcase half 10 by the mount bolt 38, an end portion of the coil spring 31 having a free length is received by the spring-receiving recessed portion d of the intermediate portion 32n, and, in this condition, the bent portion b of the free end portion 32f of the spring set plate 32 is engaged with the fork-shaped positioning portion 36 of the left-side journal wall lOj, whereby the spring set plate 32 can be positioned in an anti-rotation state. Therefore, the worker can mount the "backlash absorbing means A" without need for troublesome operations such as compressing the coil spring 31 or holding the spring set plate 32 with a hand to prevent the spring set plate 32 from rotating. When the mount bolt 3 8 is tightened, the mounting of the "backlash absorbing means A" is completed, as indicated by chain lines in Figs. 4 and 5. In this mounting completed condition, the boss portion 34 of the left-side crankcase half 10 and the recessed portion d in the intermediate portion 32n of the spring set plate 32 can be fitted to each other, and they can thereby be neatly arranged on the outside surface of the crankcase half 10, with no portion projecting from the outside surface of the crankcase half 10. As has been above-mentioned, the mounting of the "backlash absorbing means A" can be conducted from the outside of the left-side crankcase half 10, the mountability is extremely good. [0025] As shown in Fig. 4, in the completely mounted state of the "backlash absorbing means A", the spring set plate 32 pushes the push plug 3 0 inwards through the coil spring 31, and the slant surface 3 0s of the push plug 3 0 pushes the outer race 23 of the ball bearing BB with a skewly downward pushing force F. Of the pushing force F, the vertical component force Fr, namely, the component force Fr in the radial direction of the crankshaft 6 pushes the outer race 23 in the radial direction, and, by this pushing force, the "backlash" in the radial direction between the outer circumferential surface of the outer race 23 and the bearing hole 18 can be absorbed, or eliminated. Therefore, in the presence of loads in the radial direction on the crankshaft 5 due to an explosion force exerted on the piston 3 or the like, the crankshaft 6 can be appropriately supported without any backlash, and rattling sounds can be prevented from being generated. [0026] The acting direction of the pushing force exerted on the ball bearing BB by the "backlash absorbing means A" is set to coincide substantially with the acting direction of the maximum pressure (explosion pressure) exerted on the piston 3. Specifically, in this internal combustion engine, the position of the piston at the time of receiving the maximum explosion pressure is a little delayed behind the top dead center of the piston; in view of this, as shown in Fig. 2, the "backlash absorbing means A" is provided in the direction along the cylinder axis L-L at a position which is slightly deviated in the rotating direction of the crankshaft 6 (in the direction of arrow R in Fig. 2, or counterclockwise) from the cylinder axis L-L, as viewed from the direction of the axis of the crankshaft 6. This ensures that the direction of the pushing force exerted on the ball bearing BB by the "backlash absorbing means A" can be set to coincide substantially with the direction of the maximum pressure exerted on the crankshaft 6 from the piston 3, and the crankshaft 6 is appropriately supported by the ball bearing BB. [0027] Meanwhile, as shown in Fig. 4, the pushing force F exerted on the outer race 23 by the push plug 3 0 of the "backlash absorbing means A" generates a component force Fs in the horizontal direction, i.e., in the axial direction of the crankshaft 6. Due to this component force Fs, a thrust force in the axial direction is necessarily generated in the outer race 23, and the thrust force acts as a force for moving the outer race 23 of the ball bearing BB in the axial direction. [0028] In this embodiment, a "movement restraining means S" which will be described below is provided, whereby it is possible to receive the thrust force and to restrain the outer race 23 from moving in the axial direction. [0029] Next, the "movement restraining means S" according to the present invention will be described. The "movement restraining means S" is composed of a plurality of (in this embodiment, three) movement restraining members 40, and an engaging groove 41 which is formed in the inner circumferential surface of the outer race 23 of the ball bearing BB and with which hook portions 4Of of the movement restraining members 4 0 are loosely engaged. As shown in Fig. 7, the movement restraining member 4 0 is formed in the shape of a slender elongate plate, which is integrally provided at its tip end portion with the hook portion 4Of bent into C-shape in section. As shown in Figs. 2 and 3, the three movement restraining members 40 are radially disposed on the outside of the left-side crankcase half 10 at roughly equal intervals along the circumferential direction, and the outer ends thereof are fixed to the outside surface of the left-side crankcase half at positions on a circle concentric with the ball bearing BB by mount bolts 43. The three movement restraining members 4 0 are directed toward the center of the ball bearing BB, and the hook portions 40f at the inner ends thereof are bent toward the inside surface of the outer race of the ball bearing BB and are engaged with the engaging groove 41 formed in the inside surface of the outer race. Between each of the hook portions 40f and the engaging groove 41, a slight gap is provided in the axial direction thereof. The engagement between the hook portions 40f and the engaging groove 41 can restrain the outer race 23 of the ball bearing BB from moving in the axial direction; as a result, it is unnecessary to receive the above-mentioned thrust force by the right-side ball bearing (as in the structure disclosed in Patent Document 1), and a roller bearing BR with a smaller diameter (as compared with the ball bearing BB) can be adopted as the right-side rolling bearing, as in this embodiment. Besides, as shown in Figs. 2 and 3, when the three movement restraining members 4 0 are provided at least at three positions at intervals of 120° along the circumferential direction, the loads in the axial direction can be equally received, and the ball bearing BB can be securely prevented from falling down. [0030] Since the "movement restraining means S" is composed of the movement restraining members 4 0 fixed to the outside surface of the left-side crankcase half 10 and the engaging groove 41 formed in the inner circumferential surface of the outer race 23 of the ball bearing BB, the "movement restraining means S" is simple in structure, and, at the time of mounting the "movement restraining means S" onto the left-side crankcase half 10, it is unnecessary to provide the left-side crankcase half 10 with a mounting shape such as a cutout, and the strength of the left-side crankcase half 10 can be prevented from being spoiled. Besides, since the "movement restraining means S" can be mounted from the outside of the left-side crankcase half 10, the mounting is easy to carry out, and the mounting does not need any special equipment or jig. [0031] As shown in Figs. 1 and 2, a drive sprocket 51 for timed driving of a valve-operating camshaft 50 is fixed on the outside of the ball bearing BB of the crankshaft 6, and the drive sprocket 51 is operated in conjunction with a driven sprocket 53 fixed to the valve-operating camshaft 50 rotatably shaft-supported on the cylinder head CH, through an endless chain 52. The rotation of the crankshaft 6 is transmitted through the drive sprocket 51, the endless chain 52 and the driven sprocket 53 to the valve-operating camshaft 50. On the lower side of the crankcase 6, a chain drop preventive plate 54 for preventing the chain 52 from dropping off is fixed to the left-side crankcase half 10 by a plurality of bolts 55. As shown in Fig. 2, the chain drop preventive plate 54 has an arcuate portion opposed closely to an arcuate lower surface of the chain 52 wound around the drive sprocket 51, and the chain 52 can be prevented from dropping off by the arcuate portion. [0032] In Figs. 1 and 2, a flywheel 61 with an outer rotor 60 of an ACG fixed thereon is fixed to a left side end portion of the crankshaft 6, and a gear group 62 operated in conjunction with a transmission, a balancer and the like and a centrifugal oil filter 63 are fixed to a right side end portion of the crankshaft 6. [0033] Next, the functions of this embodiment will be described. [0034] When the internal combustion engine E is operated, the crankshaft 6 borne on the crankcase CC through the ball bearing BB and the roller bearing BR is driven to rotate, while the "backlash" in the radial direction generated between the outer race 23 of the ball bearing BB and the bearing hole 18 in the left-side crankcase half 10 can be absorbed by the "backlash absorbing means A", rattling sounds due to the "backlash" can be prevented from being generated, and the crankshaft 6 can be appropriately supported by the bearings BB and BR, thereby securing smooth and light rotation of the crankshaft 6. [0035] In addition, the movement in the axial direction of the outer race 23 of the ball bearing BB which necessarily arises from the mounting of the "backlash absorbing means A" can be restrained by the "movement restraining means S", so that, of the pair of rolling bearings for bearing the crankshaft 6, one can be composed of a roller bearing (smaller in diameter and higher in rigidity than a ball bearing), and the internal combustion engine E can thereby be made compact. [0036] While one embodiment of the present invention has been described above, the present invention is not limited to the embodiment, and various embodiments are possible within the scope of the invention. [0037] For example, a roller bearing or other rolling bearing may be used in place of the ball bearing on the left side, and a needle bearing or other rolling bearing may be used in place of the roller bearing on the right side. [Description of Reference Characters] [0039] 6: Crankshaft 10: Crankcase (Left-side crankcase half) 18: Bearing hole 23 : Outer race 40: Movement restraining member 40f: Hook portion 41: Engaging groove A: Backlash absorbing means BB: Rolling bearing (Ball bearing) S: Movement restraining means WE CLAIM: 1. A bearing structure for crankshaft in internal combustion engine, comprising a crankshaft (6) rotatably supported on a crankcase (10) through rolling bearing (BB), a backlash generated in the radial direction between an outer race (23) of said rolling bearing (BB), and a bearing hole (18) in said crankcase (10) being absorbed by a backlash absorb mechanism (A) provided between said outer race (23) of said rolling bearing (BB) and said crankcase (10), wherein said backlash absorbing mechanism (A) is provided with a push plug (30) which has an slant surface (30s) and pushes an outer circumferential surface of the outer race (23) to an inward direction of the crankshaft (6) by a pushing force (F), the backlash absorbing mechanism (A) absorbs said backlash according to a radial direction of the crankshaft (6) by a component force (Fr) of the pushing force (F), a movement restraining member (40) for restraining said outer race (23) moving to the inward direction of the crankshaft (6) by the pushing force (F) of the push plug (30) is engaged with the outer race (23), the movement restraining member (40) is fixed by a bolt (43) to an outside surface of a crankcase (10), the movement restraining member (40) and a bolt (43) are shifted to a circumferential direction of a crankshaft (6) from said backlash absorbing mechanism (A), and the movement restraining member (A) is arranged the inward direction of the crankshaft (10) rather than an outer surface of the backlash absorbing mechanism (A); a movement restraining means (S) for restraining said outer race (23) moving to an axial direction of the crankshaft (6) is arranged between said outer race (23) of said backlash absorb mechanism (A) and said crankcase (10). the movement restraining means (S) is comprised with an engaging groove (41) provided in the inner circumferential surface of said outer race (23), and a movement restraining member (40) provided on the outside surface of said crankcase (10, and a hook portion (40f) of said movement restraining member (40) is engaged with said engaging groove (41). 2. A bearing structure for crankshaft in internal combustion engine as claimed in the claim 1, wherein said movement restraining member (40) has a hooking portion (40f) which is engaged with an engaging groove (41) formed in the inside surface of the outer race (23). 3. A bearing structure for crankshaft in internal combustion engine as claimed in claims 1 to 2, wherein said crankshaft (6) is rotatably supported via a pair of rolling bearing (BB, BR), one of the pair of rolling bearing (BB, BR) is a ball bearing (BB) and includes said backlash absorb mechanism (A) which is arranged between outer race (23) and crankcase (10), an inner race (22) of said ball bearing (BB) is press fitted in a journal shaft portion (6j l) of the crankshaft (6) 4. A bearing structure for crankshaft in internal combustion engine as claimed in the claim 3, wherein another of the pair of rolling bearing (BB, BR) is a roller bearing (BR). 5. A bearing structure for crankshaft in internal combustion engine as claimed in the claim 4, wherein an outer race (27) of said roller bearing (BR) is press fitting in a bearing hole (19) of the crankcase (10). 6. A bearing structure for crankshaft in internal combustion engine substantially as hereinbefore described with reference to the accompanying drawings.

Documents:

1471-DEL-2004-Abstract-(28-04-2010).pdf

1471-del-2004-abstract.pdf

1471-DEL-2004-Claims-(23-09-2011).pdf

1471-DEL-2004-Claims-(28-04-2010).pdf

1471-del-2004-claims.pdf

1471-del-2004-Correspondence Others-(15-07-2014).pdf

1471-DEL-2004-Correspondence Others-(23-09-2011).pdf

1471-DEL-2004-Correspondence-Others-(28-04-2010).pdf

1471-del-2004-correspondence-others.pdf

1471-DEL-2004-Description (Complete)-(28-04-2010).pdf

1471-del-2004-description (complete).pdf

1471-del-2004-drawings.pdf

1471-DEL-2004-Form-1-(28-04-2010).pdf

1471-del-2004-form-1.pdf

1471-DEL-2004-Form-13-(23-09-2011).pdf

1471-del-2004-form-2.pdf

1471-DEL-2004-Form-3-(28-04-2010).pdf

1471-del-2004-form-3.pdf

1471-del-2004-form-5.pdf

1471-DEL-2004-GPA-(28-04-2010).pdf

1471-del-2004-gpa.pdf

1471-DEL-2004-Petition-137-(28-04-2010).pdf

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