Title of Invention

CRANKSHAFT SUPPORT STRUCTURE

Abstract

[Document Name] Abstract of the Disclosure [Abstract] [Problem] To provide a crankshaft support structure which allows the lubricant in the crank chamber to be sealed with a simple structure. [Solution] In the crankshaft support structure including a right ball bearing 33 which is fit with a right bearing support hole 66 formed in a crankcase 5 to rotatably support a crankshaft 11, and bearing urging means 68 which elastically presses an outer ring 33a of the right ball bearing 33 in a direction away from an inner surface of the right bearing support hole 68, the bearing urging means 68 includes a spring bearing member 70 fixed to the crankcase 5 and a spring urging member 69 urged to be supported at the spring bearing member 70 to be engaged with the outer ring 33a of the right ball bearing 33 A storage hole 67 is formed in a right wall portion 65 of the crankcase 5 with the right bearing support hole 66 formed therein, having one end provided with the spring urging member 69 in communication with the right bearing support hole 66, and an opening 67a of the other end to which the spring bearing member 70 is fixed to accommodate the bearing urging means 68 to be stored therein. The opening 67a is sealed with the spring bearing member 70. [Selected figure] Fig. 3

Full Text

[Document Name] Specification [Title of the Invention] CRANKSHAFT SUPPORT STRUCTURE [Technical Field] [0001] The present invention relates to a crankshaft support structure. [Background Art] [0002] A crankshaft for converting the linear movement of the piston which slides through the cylinder into the rotary movement is supported at a crankcase through a ball bearing. If a gap exists between the crankcase and an outer ring of the ball bearing a crank hammering sound may be generated during the sliding motion of the piston. A crankshaft support structure has been disclosed for suppressing generation of the crank hammering sound in the stable manner by means of bearing urging means for elastically pressing the outer ring of the ball bearing (for example, see Patent Document 1). [0003] [Patent Document 1] JP-A No. 2004-116705 [Disclosure of the Invention] [Problem to be Solved by the Invention] [0004] However, in the case where the aforementioned crankshaft support structure is applied to the structure having a dry space where a cooling air passage and the like is formed at the side of a crankcase, a mechanism for sealing a lubricant is required to be disposed between an outer ring of a ball bearing and the crankcase. This may cause the disadvantages of complicating the structure, and increasing the cost. [0005] It is an object of the present invention to provide a crankshaft support structure which makes sure to seal the lubricant within the crank chamber with the simple structure. [Means for Solving the Problem] [0006] For solving the aforementioned problem, the crankshaft support structure according to the present invention includes a bearing (for example, a right ball bearing 33 in the embodiment) which is fit with a bearing support hole (for example, a right bearing support hole 66) formed in a crankcase to rotatably support a crankshaft, and bearing urging means which elastically presses an outer ring of the bearing in a direction away from an inner surface of the bearing support hole. The bearing urging means includes a spring bearing member fixed to the crankcase and a spring urging member urged to be supported at the spring bearing member to be engaged with the outer ring of the bearing. A storage hole is formed in a wall portion (for example, a right wall portion 65 in the embodiment) of the crankcase with the bearing support hole formed therein, having one end provided with the spring urging member in communication with the bearing support hole, and an opening of the other end to which the spring bearing member is fixed to accommodate the bearing urging means to be stored therein. The opening is sealed with the spring bearing member. [0007] In the crankshaft support structure according to the present invention, preferably, a generator mount hole is provided for accommodating a generator in a space at a side where the opening is formed to interpose the wall portion, and fixing a stator of the generator adjacent to the storage hole. [0008] Preferably, an auxiliary drive portion (for example, an oil pump drive gear 51) is provided on the crankshaft adjacent to the bearing for driving an auxiliary unit (for example, an oil pump 53 in the embodiment), and the storage hole is formed around the auxiliary drive portion. [0009] Further preferably, the bearing urging means is provided at a side of a piston with respect to an axis of the crankshaft. [Effect of the Invention] [0010] By informing the crankshaft support structure according to the present invention as described above, the bolt hole for holding the bearing urging means is not required in addition to the storage hole for storing the bearing urging means. As the hole may be processed only at a single position, the man-hour for the process may be reduced, and the structure may be made compact. As the spring plate bearing is not required, the number of required parts may also be reduced. Even when the dry space is formed in the outer space of the bearing, the lubricant within the crank chamber may be reliably sealed with the simple structure without being complicated. [0011] In the case where the generator support hole is formed around the storage hole for supporting the stator of the generator, those storage hole and the support hole may be processed using the same member in the same direction, thus reducing both the man-power for the process and the cost. [0012] By providing the auxiliary drive unit at the side of the bearing, adjacent to which the storage hole is processed, the auxiliary drive unit may be arranged to be compact by the use of the dead space around the storage hole. [0013] By disposing the bearing urging means at the piston side with respect to the axis of the crankshaft, the bearing may be urged on the crankshaft in the explosion pressure bearing direction. This makes it possible to effectively suppress the crank hammering sound. [Best Mode for Carrying out the Invention] [0014] A preferred embodiment of the present invention will be described referring to the drawings. Referring to Figs. 1 and 2, a structure of a power unit 1 to which the crankshaft support structure according to the present invention is applied will be described. The power unit 1 is installed in the two-wheeled vehicle. In the following explanation, the direction indicated by arrows F and U denote the forward and upper directions, respectively. [0015] The power unit 1 is formed of a cylinder head cover 2, a cylinder head 3, a cylinder block 4, a crankcase 5, a crankcase cover 6 and a gear case 7. A cylinder sleeve 8 cylindrically extending in the longitudinal direction is press fit into the cylinder block 4. A cylinder chamber 8a is formed around the cylinder sleeve 8. A piston 9 which slidably reciprocates in the longitudinal direction is disposed in the cylinder chamber 8a. The piston 9 is connected to a crankshaft 11 laterally extending to be rotatably held in the crank chamber 5a formed in the crankcase 5 via a connecting rod 10 The crankshaft 11 is formed of a left crankshaft half IIL and a right crankshaft half IIR. The connecting rod 10 is connected to the crankshaft 11 via a crankpin 12 which is disposed to link the left and right crankshaft halves IIL, IIR. [0016] A combustion chamber 13 defined by the cylinder sleeve 8, the cylinder head 3 and the piston 9 is communicated with an intake port 16 and an exhaust port 17 via an inlet 14 and an outlet 15 formed in the cylinder head 3, respectively. Mushroom-like intake valve 18 and exhaust valve 19 are urged in the direction to normally close the inlet 14 and the outlet 15 by valve springs 20 and 21 each having one end connected to a valve shaft to be supported at a retainer, and the other end supported at the cylinder head 3. [0017] The cylinder head 3 rotatably supports a camshaft 22 which laterally extends to open and close the intake valve 18 and the exhaust valve 19. A timing chain 25 is wound around a cam driven sprocket 23 attached to the camshaft 22 and a cam drive sprocket 24 attached to the crankshaft 11 (left crankshaft half IIL). The camshaft 22 rotates accompanying the rotation of the crankshaft 11, and cams 26 and 27 formed on the camshaft 22 push each one end of rocker arms 28 and 29 forward such that each of the other ends of the rocker arms 28 and 29 rocks rearward to push the intake valve 18 and the exhaust valve 19 so as to open and close the inlet 14 and the outlet 15. [0018] A throttle body 30 having a throttle valve is communicated with the intake port 16 for adjusting an amount of intake air cleaned by a not shown air cleaner so as to be mixed with the fuel, and then supplied from the intake port 16 to the combustion chamber 13 via the inlet 14. The air-fuel mixture is compressed by the piston 9, and ignited with a spark plug 31 attached to the cylinder head 3 for combustion. The resultant energy serves to rotate the crankshaft 11 via the piston 9. Thereafter, it is discharged from the outlet 15 via the exhaust port 17 as an exhaust gas. [0019] Each proximal end of journal portions of left and right crankshaft halves IIL and IIR which form the crankshaft 11 is rotatably supported at the crankcase 5 via the left and right ball bearings 32 and 33, respectively. The left side portion of the crankcase 5 is formed to extend backward. A crankcase cover 6 is attached to the left side surface of the crankcase 5. A transmission 35 is stored in a transmission chamber 34 defined by the crankcase 5 and the crankcase cover 6. A countershaft 36 disposed to the rear of the crankshaft 11, extending substantially in parallel therewith, and rotatably supported at the crankcase 5 and the crankcase cover 6 is attached to the transmission chamber 34. [0020] The transmission 35 is formed of a drive pulley 37 attached to the journal portion of the left crankshaft half IIL extending within the transmission chamber 34 so as to be integrally rotatable, a driven pulley 38 attached to substantially a center of the countershaft 36 so as to be rotatable relative thereto, a clutch 39 attached to a left end portion of the countershaft 36 for bringing the driven pulley 38 and the countershaft 36 into engagement/disengagement, and a V-belt 40 wound around the drive pulley 37 and the driven pulley 38 so as to transmit the rotation of the drive pulley 37 to the driven pulley 38. [0021] The drive pulley 37 includes a fixed pulley half body 37a attached to the journal portion of the left crankshaft half IIL so as to be integrally rotatable, and a movable pulley half body 37b axially movable relative to the fixed pulley half body 37a so as to be integrally rotatable with the left crankshaft half IIL. The V-belt 40 is interposed between the fixed and movable pulley half bodies 37a and 37b. Meanwhile, the driven pulley 38 is formed of a fixed pulley half body 38a attached to the countershaft 36 relatively rotatable, and a movable pulley half body 38b axially movable relative thereto, and rotatable relative to the countershaft 36. The V-belt 40 is interposed between the fixed and the movable pulley half bodies 38a and 38b. [0022] A ramp plate 41 is fixed to the left crankshaft half IIL outside the movable pulley half body 37b (at the side of the left ball bearing 32) forming the drive pulley 37 to cover the outer side of the movable pulley half body 37b. A weight roller space 42 is defined by the movable pulley half body 37b and the ramp plate 41 for storing a weight roller 43. The weight roller space 42 is formed to reduce its lateral distance as it moves outward away from the crankshaft 11. The movable pulley half body 38b which forms the driven pulley 38 is disposed alongside the clutch 39. A spring 44 is disposed between the movable pulley half body 38b and the clutch 39 to urge the movable pulley half body 38b on the fixed pulley half body 38a. [0023] With the above-structured transmission 35, the drive pulley 37 rotates as the crankshaft 11 is driven to rotate, and the resultant rotation is transmitted to the driven pulley 38 via the V-belt 40. The countershaft 36 is further driven to rotate via the clutch 39. The magnitude of the centrifugal force acting on the weight roller 43 varies in accordance with the rotating speed of the crankshaft 11. The weight roller 43 pushes the movable pulley half body 37b leftward in accordance with the magnitude of the centrifugal force such that the winding radius of the V-belt 40 with respect to the drive pulley 37 varies. The movable pulley half body 38b of the driven pulley 38 laterally slides so as to balance between the tension force of the V-belt 40 and the urging force of the spring 44. As the winding radius of the drive pulley 37 changes, the tension force of the V-belt 40 changes. Accordingly, the winding radius of the V-belt 40 with respect to the driven pulley 38 changes. The transmission 35 is structured to steplessly (continuously) change the transmission ratio by sequentially changing the winding radius of the V-belt 40 around the pulleys 37 and 38, respectively in accordance with the rotating speed of the crankshaft 11. [0024] A gear case 7 is attached to the rear of the crankcase 5 such that the right side surface of the rear portion is covered. A gear chamber 45 is defined by the rear portion of the crankcase 5 and the gear case 7. A right end portion of the countershaft 36 supported at the crankcase 5 protrudes to the inside of the gear chamber 45. The countershaft 36 is provided with an idle shaft 46 substantially in parallel with the countershaft 36 and rotatably held at the crankcase 5 and the gear case 7 to the rear of the countershaft 36, and a rear wheel shaft (final shaft) 47 substantially in parallel with the countershaft 36 and rotatably held at the crankcase 5 and the gear case 7 further to the rear of the countershaft 36. A reduction gear train 48 is disposed at the countershaft 36, the idle shaft 46 and the rear wheel shaft 47. The rotation of the countershaft 36 is transmitted to the rear wheel shaft 47 via the reduction gear train 48 so as to drive to rotate the rear wheel (not shown) to which the rear wheel shaft 47 is attached. [0025] A drum brake 49 for braking the rotation of the rear wheel shaft 47 is disposed between the gear case 7 and the rear wheel shaft 47. A kick start-up mechanism 50 is disposed at the left side to the rear of the left crankshaft half IIL. [0026] A proximal end portion of the journal portion of the right crankshaft half IIR is supported at the crankcase 5 via the right ball bearing 33. The journal portion is provided with an oil pump drive gear 51 so as to be adjacent to the right side of the right ball bearing 33. An oil pump 53 is disposed at the lower portion of the right crankshaft half IIR. A pump shaft 54 of the oil pump 53 is provided with an oil pump driven gear 52 in mesh with the oil pump drive gear 51. Accordingly, the rotation of the crankshaft 11 is transmitted to the oil pump drive gear 51 and the oil pump driven gear 52 to rotate the pump shaft 54 such that the oil pump 53 is driven. [0027] A portion of the right crankshaft half IIR rightward of the oil pump drive gear 51 externally protrudes from the crankcase 5. A stator 56 which forms a generator 55 is attached to the outer right side of the crankcase 5 to surround the journal portion of the right crankshaft half IIR protruding from the case 5 with a bolt 58. A rotor 57 which forms the generator 55 is attached to the journal portion of the right crankshaft half IIR so as to surround the outer circumference of the stator 56. When the crankshaft 11 is driven to rotate, the rotor 57 starts rotating around the stator 56 such that power is generated by the generator 55. An oil seal 59 is provided between the right crankshaft half IIR and the crankcase 5 so as to prevent the lubricant supplied into the crankcase 5 from leaking to the generator 55. [0028] A cooling fan 60 is attached to the leading end of the right crankshaft half llR. The right side of the power unit 1 is covered with the engine cover 61, and air vent holes 62 are formed on an extended line of the right crankshaft half IIR of the engine cover 61. When the crankshaft 11 is driven to rotate, external air is taken by the cooling fan 60 into the engine cover 61 via the air vent holes 62. The intake air flows through a cooling air passage 61a surrounded by the engine cover .61 around the cylinder head 3 and the cylinder block 4 so as to be cooled. [0029] The structure of the aforementioned power unit 1 for supporting the crankshaft 11 will be described referring to Figs. 3 and 4. As described above, the left and right crankshaft halves IIL and IIR are supported at the crankcase 5 via the left and right ball bearings 32 and 33, respectively. Those ball bearings 32, 33 are attached by fitting the left ball bearing 32 with the left bearing support hole 64 formed in the left wall portion 63 which forms the crank chamber 5a from the right, and the right ball bearing 33 with a right bearing support hole 66 formed in a right wall portion 65 which forms the crank chamber 5a from the left, respectively. [0030] A storage hole 67 with an opening 67a on the outside which extends rightward in communication with the right bearing support hole 66 is formed in the right wall portion 65 to which the right ball bearing 33 is attached. Bearing urging means 68 formed of a spring urging member 69 and a spring bearing member 70 is inserted to be fit with the storage hole 67. [0031] The spring urging member 69 has a cylindrical shape, and includes a runner 69a slidably movable through the storage hole 67 and a spring 69c inserted into a spring attachment hole 69b which is opened to the right end surface of the runner 69a and extending inward. A tapered face 69d is formed on the left end portion of the runner 69a. Meanwhile, the spring bearing member 70 includes a screw portion 70a having a male thread formed on the cylindrical circumferential surface therein, and a flange portion 70b formed into a disk-like shape at the right end. The spring urging member 69 is inserted into the storage hole 67 from the tapered surface 69d of the runner 69a such that the screw portion 70a is screwed with the female thread formed in the inner peripheral surface of the opening portion 67a of the storage hole 67 to install the spring bearing member 70. A washer 71 is installed between the flange portion 70b and the right wall portion 65. [0032] In the above-structured bearing urging means 68, the tapered surface 69d of the runner 69a inserted into the storage hole 67 abuts on the lower right side of an outer ring 33a which forms the right ball bearing 33. When the spring bearing member 70 is screwed with the storage hole 67, the spring 69c of the spring urging member 69 is pushed leftward by the spring bearing member 70 such that the runner 69a is pushed rightward. The tapered surface 69d of the runner 69 serves to elastically push up the outer ring 33a of the right ball bearing 33 in the direction of the rotating axis of the crankshaft 11, that is, the direction in which the outer ring 33a is moved away from the inner surface of the right bearing support hole 66. The spring 69c is capable of absorbing the impact resulting from the sliding motion of the piston 9 so as to allow the right ball bearing 33 to be supported in the stable state. [0033] The sealant is applied to the screw portion 72 between the storage hole 67 and the spring bearing member 70 so as to be screwed, thus preventing leakage of the lubricant within the crank chamber 5a to the generator 55. [0034] The bearing urging means 68 is formed of the spring urging member 69 which elastically presses the right ball bearing 33, and the spring bearing member 70 screwed with the storage hole 67 to bear the spring 69c of the spring urging member 69 inserted into the storage hole 67 . Accordingly, a bolt hole for pressing the spring urging member 69 does not have to be formed in addition to the storage holt 67. Only a single hole may be processed, thus reducing the man-hours for the process and making the structure compact. As the spring plate bearing is not required, the number of parts may be reduced. In the case where the outer space of the right wall portion 65 to which the right ball bearing 33 is attached is formed as the dry space (where the lubricant is not supplied) provided with a cooling air passage 61, the lubricant within the crank chamber 5a may be securely sealed with the simple structure by applying the sealant to the screw surface between the storage hole 67 and the spring bearing member 70 without complicating the structure. [0035] As shown in the embodiment, in the structure where a generator support hole 72 for fixing the stator 56 of the generator 55 is formed in the right wall portion 65 of the crankcase 5 in which the storage hole 67 is formed, and the stator 56 is attached by threading the bolt 58 into the generator support hole 72, the generator support hole 72 and the storage hole 67 may be processed in the same direction with the same member. This makes it possible to reduce the man-hours for the process, as well as reduce the cost. The auxiliary drive portion for driving the auxiliary unit such as the oil pump 53, that is, the oil pump drive gear 51 may be disposed to the side (right side) of the right ball bearing 33 by the use of the dead space around the storage hole 69, thus arranging the oil pump drive gear 51 in the compact manner. [0036] Referring to Fig. 2, in the embodiment, the storage hole 69 is formed at the opposite side of the piston 9 with respect to the axis of the crankshaft 11. However, the storage hole may be formed at the side of the piston 9 (the position designated with the code 69' ) with respect to the axis of the crankshaft 11. When the air-fuel mixture is combusted in the combustion chamber 13, the force exerted from the piston 9 to the crankshaft 11 acts rearward as shown in Fig. 2. If the storage hole is formed at the position designated with the code 69' , the direction in which the bearing urging means urges the right ball bearing 33 substantially coincides with the direction in which the explosion pressure is exerted to the piston 9. This makes it possible to further suppress generation of the crank hammering sound. [0037] The method for sealing the bearing urging means 68 is not limited to the application of the sealant to the screw portion 72 as shown in Fig. 4(a). For example, a ring groove 70c is formed on the flange portion 70b of the spring bearing member 70 to surround the screw portion 70a so as to fit an 0-ring 74 with the ring groove 70c as shown in Fig. 4(b) . In this case, when the spring bearing member 70 is screwed with the storage hole 67, the 0-ring 74 is pinched between the outer side surface of the crankcase 5 and the flange portion 70b to seal the lubricant. A ring groove 70d may be formed on the side surface of the screw portion 70a of the spring bearing member 70 to fit an 0-ring 75 with the ring groove 70d as shown in Fig. 4(c). Alternatively, the inner periphery of an opening portion 67a of the storage hole 67 is set to be large to fit an 0-ring 76 therewith as shown in Fig. 4(d). [Brief Description of the Drawings] [0038] [Fig. 1] is a plan view of a power unit equipped with a crankshaft support structure according to the present invention. [Fig. 2] is a side view of an essential portion of the power unit when viewed from the right. [Fig. 3] is a sectional view showing an essential portion of the crankshaft support structure. [Fig. 4] is an explanatory view showing a method for sealing the bearing urging means, wherein Fig. 4(a) shows a structure where the sealant is applied to the screwed portion, Fig. 4(b) shows the structure where the flange portion is provided with the 0-ring, Fig. 4(c) shows the structure where the 0-ring is fit with the flange portion, and Fig. 4(d) is a structure where the 0-ring is fit with the opening of the storage hole. [Description of Reference Numerals] [0039] 5... Crankcase 11... Crankshaft 33... Right ball bearing (bearing) 33a... Outer ring 51... Oil pump drive gear (auxiliary drive portion) 53... Oil pump (auxiliary unit) 55... Generator 56... Stator 65... Right side wall (wall portion) 66... Right bearing support hole (bearing support hole) 67... Storage hole 67a... Opening 68... Bearing urging means 69... Spring urging means 70... Spring bearing member 73... Generator mount hole [Document Name] Scope of Claims [Claim 1] A crankshaft support structure comprising: a bearing which is fit with a bearing support hole formed in a crankcase to rotatably support a crankshaft; and bearing urging means which elastically presses an outer ring of the bearing in a direction away from an inner surface of the bearing support hole wherein: the bearing urging means includes: a spring bearing member fixed to the crankcase; and a spring urging member urged to be supported at the spring bearing member to be engaged with the outer ring of the bearing, a storage hole is formed in a wall portion of the crankcase with the bearing support hole formed therein, having one end provided with the spring urging member in communication with the bearing support hole, and an opening of the other end to which the spring bearing member is fixed to accommodate the bearing urging means to be stored therein; and the opening is sealed with the spring bearing member. [Claim 2] The crankshaft support structure according to Claim 1, wherein a generator mount hole for accommodating a generator in a space at a side where the opening is formed to interpose the wall portion, and fixing a stator of the generator adjacent to the storage hole. [Claim 3] 2, wherein an auxiliary drive portion is provided on the crankshaft adjacent to the bearing for driving an auxiliary unit, and the storage hole is formed around the auxiliary drive portion. [Claim 4] The crankshaft support structure according to any one of Claims 1 to 3, wherein the bearing urging means is provided at a side of a piston with respect to an axis of the crankshaft.

Documents:

2974-CHE-2007 AMENDED CLAIMS 21-12-2011.pdf

2974-CHE-2007 EXAMINATION REPORT REPLY RECEIVED 21-12-2011.pdf

2974-CHE-2007 FORM-3 21-12-2011.pdf

2974-CHE-2007 OTHER PATENT DOCUMENT 21-12-2011.pdf

2974-che-2007 abstract.pdf

2974-che-2007 claims.pdf

2974-che-2007 correspondence others.pdf

2974-che-2007 description (complete).pdf

2974-che-2007 drawings.pdf

2974-che-2007 form-1.pdf

2974-che-2007 form-18.pdf

2974-che-2007 form-26.pdf

2974-che-2007 form-3.pdf

2974-che-2007 form-5.pdf

2974-che-2007 others.pdf