CA2440928C

CA2440928C - Wheel for bicycle

Info

Publication number: CA2440928C
Application number: CA002440928A
Authority: CA
Inventors: Hisatoshi Kobayashi
Original assignee: Honda Motor Co Ltd
Current assignee: Honda Motor Co Ltd
Priority date: 2002-09-26
Filing date: 2003-09-12
Publication date: 2007-05-01
Anticipated expiration: 2023-09-12
Also published as: MXPA03008414A; BR0304204B1; BR0304204A; CN1496864A; ES2265205A1; JP2004114861A; CA2440928A1; ES2265205B1

Abstract

To realize the reduction of cost by reducing man-hours for manufacturing a wheel for a bicycle in which, to an axle sleeve which is rotatably supported on an axle, a hub which surrounds the axle sleeve is fixed, and a plurality of wire spokes are provided between a rim which supports a tire and the hub. A support member 203 which includes a cylindrical support portion 203a which concentrically surrounds the axle sleeve 202 is fixedly mounted on the axle sleeve 202, the hub 204 is formed to integrally incorporate a cylindrical portion 204a which is fixedly mounted on an outer periphery of the cylindrical support portion 203a and a pair of flanges 204b which extend outwardly in the radial direction from both ends of the cylindrical portion 204a, and connection holes 208 with which inner ends of respective wire spokes 207 are engaged are respectively formed in both flanges 204b.

Description

WHEEL FOR BICYCLE
FIELD OF THE INVENTION
The present invention relates to a wheel for a bicycle in which, to an axle sleeve which is rotatably supported on an axle, a hub which surrounds the axle sleeve is fixedly mounted and a plurality of wire spokes are formed between a rim which supports a tire and the hub.
BACKGROUND OF THE INVENTION
Such a wheel for a bicycle has been already known in a following patent literature 1 and the like, for example, JP-UM-B-58-1366 However, in the above-mentioned conventional wheel for a bicycle, a pair of hub plates which are formed by molding steel plates in a dish shape using a press are welded to an axle sleeve in a state that these hub plates have backs thereof face each other and hence, to ensure the accuracy of left and right flanges for wire spokes, it is necessary to perform the accuracy control of each hub plate and the accuracy control at the Time of welding both hub plates. Further, it is necessary to position a welding jig at the time of welding both hub plates to the axle path and hence, rnan-hours for manufacturing are increased.
The present invention is made in view of such circumstances and it is an object of the present invention to provide a wheel for a bicycle which can realize the reduction of cost by reducing man-hours for manufacturing.
JJ-i2ms/c~

_2_ SUMMARY OF THE INVENTION
To achieve the above-mentioned object, according to the present invention, in a wheel for a bicycle in which, to an axle sleeve which is rotatably supported on an axle, a hub which surrounds the axle sleeve is fixed, and a plurality of wire spokes are formed between a rim which supports a tire and the hub, the improvement is characterized in that a support member which includes a cylindrical support portion which concentrically surrounds the axle sleeve is fixedly mounted on the axle sleeve, the hub is formed to integrally incorporate a cylindrical portion which is fixedly mounted on an outer periphery of the cylindrical support portion arid a pair of flanges which extend outwardly in the radial direction from both ends of the cylindrical portion, and connection holes with which inner ends of respective wire spokes are engaged are respectively formed in both flanges.
According to such a constitution, since the hub is formed by integrally forming the flange portions on both ends of the cylindrical portion, i n performing positioning of a welding jig at the time of welding the hub to the cylindrical portion of the support member, it is sufficient to perform the positioning only with respect to the hub and, further, it is possible to easily ensure the positional accuracy of the connection holes formed i n both flanges due to an accuracy control of the hub as a single product and hence, it is possible to realize the reduction of cast by reducing man-hours for manufacturing.
BRIEF DESCRIPTION OF THE DRAWINGS
Preferred embodiments of the invention are shown in the drawings, wherein:
Fig 1 is a side view of an engine-assisted bicycle of the first embodiment.
Fig. 2 is a transverse cross-sectional plain view of a rear portion of the bicycle taken along a line 2-2 in Fig. 1.
Fig. 3 is an enlarged side view of the rear portion of the bicycle.
JJ-12118/cs Fig. 4 is a cross-sectional view taken along a line 4-4 in Fig. 3.
Fig. 5is an enlarged view of a front portion in Fig. 4.
Fig. 6 is an enlarged side view with a part broken away' of a front portion of an engine body and also is a cross-sectional view taken along a line 6-6 n Fig. 7.
Fig. 7 is a cross-sectional view taken along a line 7-7 in Fig. 6.
Fig. 8 is a cross-sectional view taken along a line 8-8 in Fig. 7.
Fig. 9 is an enlarged view of an essential part in Fig. 5.
Fig. 10 is a cross-sectional view taken along a line 10-10 in Fig. 5.
Fig. 11 is a cross-sectional view taken along a line 11-11 in Fig. 10.
Fig. 12 is a cross-sectional view taken along a line 12-12 in Fig. 6.
zo Fig. 13 is an enlarged view of a rear portion in Fag. 4.
Fig. 14 is a cross-sectional view taken along a line 14-14 in Fig. 3.
Fig. 15 is a cross-sectional view taken along a line 15-15 in Fig. 1.
Fig. 16 is a cross-sectional view taken along a line 16-16 in Fig. 3.
Fig. 17 is a cross-sectional view corresponding to Fig. 5 showing the second embodiment.
Fig. 18 is a cross-sectional view corresponding to Fig. 5 showing the third embodiment.
Fig. 19 is a cross-sectional view corresponding to Fig. 5 showing the fourth embodiment.
JJ-12i1s/cs Fig. 20 is a cross-sectional view taken along a line 20-20 in Fig. 19.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
Modes for carrying out the present invention are explained hereinafter in conjunction with attached drawings.
Fig. 1 to Fig. 16 show the first embodiment of the present invention, wherein Fig. 1 is a side view of an engine-assisted bicycle, Fig. 2 is a transverse cross-sectional plan view of a rear portion of the bicycle taken along a line 2-2 in Fig. 1, Fig. 3 is an enlarged side view of the rear portion of the bicycle, Fig. 4 is a cross-sectional view taken along a line 4-4 in Fig. 3, Fig. 5 is an enlarged view of a front portion in Fig. 4, Fig. 6 is an enlarged side view with a part broken away of a front portion of an engine body and is also a cross-sectional view taken along a line 6-6 in Fig. 7, Fig. 7 is a cross-sectional view taken along a line 7-7 in Fig. 6, Fig. 8 is a cross-sectional view taken along a line 8-8 in Fig. 7, Fig. 9 is an enlarged view of an essential part in Fig. 5, Fig. 10 is a cross-sectional view taken along a line 10-10 in Fig. 5, Fig. 11 is a cross-sectional view taken along a line 11-in Fig. 10, Fig. 12 is a cross-sectional view taken along a line 12-12 in Fig.
6, Fig. 13 is an enlarged view of a rear portion of Fig. 4, Fig. 14 is an enlarged cross-sectional view taken along a line 14-14 in Fig. 3, Fig. 15 is a cross-sectional view taken along a line 15-15 in Fig. 1, and Fig. 16 is a cross-sectional view taken along a line 16-16 in Fig. 3.
First of all, in Fig. 1, a body frame 15 of an engine-assisted bicycle includes a main frame 17 which has a front end on which a head pipe 16 is formed and is inclined backwardly and downwardly, a seat post 18 which is contiguously formed on a rear portion of the main frame 17 and extends upwardly, a support stay 19 which is formed in a U shape opened in a frontward direction and has both ends thereof fixedly mounted on the seat post 18, and reinforcing members 20... which extend rearwardly and upwardly from the seat post 18 such that the reinforcing members 2D...
connect both left and right sides of the support stay 7.9... and the seat post 18.
A front fork 21 is supported on the head pipe 26 such that the front fork 21 can be steered, a front wheel WF is pivotally supported on a lower end of JJ-12118/cs the front fork 21, and a bar-like steering handle 22 is mounted on an upper end of the front fork 21. That is, the front fork 21 and the steering handle 22 are supported on the head pipe 16 such that they can be steered.
Brake levers 23... are respectively arranged at both left and right end portions of the steering handle 22 such that they can be manipulated respectively. A manipulating force for these brake levers 23 is inputted to an equalizer 24 which is arranged in front of the head pipe 16 and is supported on the head pipe 16. The equalizer 24 is configured such that whichever one of left and right brake levers 23 is manipulated, the brake manipulating force is transmitted to both of a front-wheel brake BF
mounted on the front wheel WF and a rear-wheel brake BR mounted o n the rear wheel WR. Further, on a basket support member 25 which is provided between an upper portion of the front fork 21 and the steering handle 22, a basket 26 which is arranged in front of the steering handle 22 and the head pipe 16 and a head lamp 27 which is arranged below the basket 27 are supported.
In conjunction with both of Fig. 2 and Fig. 3, a seat support pipe 29 which is provided with a saddle-like seat 28 on an upper end thereof is inserted into the seat post 18 from above, wherein a driver sits on the seat 28. The seat support pipe 29 is fixed to the seat post 18 such that the vertical position of the seat support pipe 29 can be adjusted.
A fuel tank 30 which is arranged behind the seat 28 and in the oblique downward direction is supported on the above-mentioned support stay 19, while an electronic control unit 31 which controls the operation of an engine E mounted on the vehicle body frame 15 is mounted on a lower surface of the fuel tank 30. Further, on a rear portion of the support stay 19, a pair of left and right rear blinkers 32, 32 and a rear lamp 33 which is arranged between the rear blinkers 32, 32 are mounted.
On a rear portion of the vehicle body frame 15, a power unit P which includes a four-cycle SOHC type engine E and a power transmission device T which transmits an output of the engine E to the rear wheel WR by shifting the output of the engine E is supported such that the power unit P
is tiltable in the vertical direction. An axle of the rear wheel WR is JJ-12118/cs - U -pivotally supported on the rear portion of the power unit P. Further, it is also possible to transmit an operating force which is generated when a rider on the seat 28 steps on a pair of left and right crank pedals 34 ... to the above-mentioned rear wheel WR.
In Fig. 4 and Fig. 5, the engine E is a single cylinder air-cooled engine which has a crankshaft 37 extending horizontally in the left-and-right direction of the vehicle body frame 15. An engine body 38 includes a crankcase 39 which rotatably supports the crankshaft 37, a cylinder block 40 which has a cylinder axis C extending slightly upwardly in the frontward direction from the crankcase 39 and is connected to the crankcase 39, a cylinder head 41 which is connected to the cylinder block 40, and a head cover 42 which is connected to the cylinder head 41 at a side opposite to the cylinder block 40. A plurality of cooling fins 40a ..., 41a ... are formed on respective outer surfaces of the cylinder block 40 and the cylinder head 41 in a projecting manner.
The crankcase 39 is formed by coupling a pair of left and right case halves 39L, 39R with each other on a coupling surface 134 which is arranged along a vertical plane including an cylinder axis C. The crankshaft 37 is supported on the case halve 39R by way of a ball bearing 47 and is supported on the case halve 39L by way of a ball bearing 48. A piston 44 which is slidably fitted into a cylinder bore 43 formed in the cylinder block 40 is connected to the crankshaft 37 by way of a connecting rod 45 and a crank pin 46. Further, outside the ball bearing 47 and between the crankshaft 37 and the case halve 39R, an annular seal member 49 is provided.
Further, one end portion of the crankshaft 37 is projected from the crankcase 39 at the right side along the advancing direction of the engine-assisted bicycle and an AC generator 52 is connected to one end portion of the crankshaft 37. The AC generator 52 is constituted of a rotor 50 which is fixed to one end portion of the crankshaft 37 and a stator 51 housed in the rotor 50. The AC generator 52 is covered with the crankcase 39 and a right engine cover 53 which is connected to the cylinder block 40, while the stator 51 is fixed to the crankcase 39.
IJ-1211s~cs _7_ To explain the embodiment in conjunction with all of Fig. 6 to Fig. 8, in the cylinder head 41, an intake port 56 and an exhaust port 57 which are communicated with a combustion chamber 55 are formed, wherein the combustion chamber 55 is formed between the cylinder block 40 and the cylinder head 41 while facing a top portion of the piston 44. Further, an intake valve 58 and an exhaust valve 59 which respectively open or close the intake port 56 and the exhaust port 57 are arranged on the cylinder head 41.
The intake valve 58 and the exhaust valve 59 axe guided by guide sleeves 60, 61 mounted on the cylinder head 41 and perform open/close operations linearly. Between retainers 62, 63 mounted on end portions of the intake valve 58 and the exhaust valve 59 which are projected from respective guide sleeves 60, 61 and the cylinder head 41, valve springs 64, 65 are respectively provided, and the intake valve 58 and the exhaust valve 59 are respectively biased in the valve closing direction by respective valve springs 64, 65.
Further, the above-mentioned respective guide sleeves 60, 61 are mounted on the cylinder head 41 having axes which are arranged parallel to each other and are directed upwardly and the frontward direction such that a plane P1 which includes both of the axes of the guide sleeves 60, 61 intersects a plane P2 which includes the axis of the crankshaft 37 and the cylinder axis C with an acute angle. Accordingly, the intake valve 58 and the exhaust valve 59 are arranged on the cylinder head 41 such that they are operated in the open/close operating directions which are parallel to each other.
Between the cylinder head 41 and the head cover 42, a valve actuating chamber 66 is formed. In this valve actuating chamber 66, a valve actuating device 67 which performs open/close driving of the intake valve 58 and the exhaust valve 59 which are respectively biased in the valve closing direction is housed.
The valve actuating device 67 includes a camshaft 68 which has an axis parallel to the crankshaft 37 and is rotatably supported on the cylinder head 41, a rocker shaft 69 which has an axis parallel to the camshaft 68 and JJ-12118/cs -g-is fixedly supported on the cylinder head 41, an intake-side rocker arm 70 which is tiltably supported on the rocker shaft 69 and is interposed between the camshaft 68 and the intake valve 58, and an exhaust-side rocker arm 71 which is tiltably supported on the rocker shaft 69 together with the intake-side rocker arm 70 and is interposed between the camshaft 68 and the exhaust valve 59.
An intake-side cam 72 and an exhaust-side cam 73 are respectively formed on the camshaft 68. A tappet screw 74 which is brought into contact with an end portion of the intake valve 58 is threaded into another end portion of the intake-side rocker arm 70 which includes a cam slipper 70a which is brought into slide contact with the intake-side cam 72 at one end thereof such that the advancing/retracting position of the tappet screw 74 can be adjusted. Further, a tappet screw 75 which is brought into contact with an end portion of the exhaust valve 59 is threaded into another end portion of the exhaust-side rocker arm 71 which includes a cam slipper 71a which is brought into slide contact with the exhaust-side cam 73 at one end thereof such that the advancing/retracting position of the tappet screw 75 can be adjusted.
Here, the camshaft 68 is arranged closer to the combustion chamber 55 than interlocking connecting points between the intake-side and the exhaust-side rocker arms 70, 71 and the intake valve 58 and the exhaust valve 59, that is, contact points of the tappet screws 74, 75 with the intake valve 58 and the exhaust valve 59. In this embodiment, the camshaft 68 is arranged above the intake valve 58 and the exhaust valve 59.
Further, the intake port 56 is formed in the cylinder head 41 such that the intake port 56 is arranged at a position remote fram one end of the camshaft 68 in the axial direction such that at least a portion (a portion i n this embodiment) of the camshaft 68 is overlapped to the intake port 56 o n a projected view (see Fig. 8) to a plane orthogonal to the axis of the camshaft 68 and, at the same time, the intake port 56 intersects the rocker shaft 69 on a projected view (see Fig. 7) to a plane orthogonal to the cylinder axis C.
JJ-12118/cs Opening ends of the intake port 56 and the exhaust port 57 to the combustion chamber 55 are, as explicitly shown in Fig. 7, arranged on one straight line which is parallel to the axes of the camshaft 68 and the rocker shaft 69, while the intake port 56 has an outer end thereof opened in an upper side wall of the cylinder head 41 and the exhaust port 57 has an outer end thereof opened in a lower side wall of the cylinder head 41.
Further, an ignition plug 76 having an axis which makes an acute angle oc with respect to the plane P1 including both of the axes of the intake valve 58 and the exhaust valve 59 is mounted on the cylinder head 41 such that the ignition plug 76 faces the combustion chamber 55.
Between the camshaft 68 and the crankshaft 37, a timing transmission mechanism 77 which transmits a rotational force of the crankshaft 37 to the camshaft 68 at a reduction gear ratio of 1/2 is provided. The timing transmission mechanism 77 includes a driving sprocket wheel 78 which is fixed to the crankshaft 37 far outside than the ball bearing 48, a driven sprocket wheel 79 which is fixed to another end portion of the camshaft 68, and an endless cam chain 80 which is wound around the driving and driven sprocket wheels 78, 79. In the engine body 38, at a portion ranging from the crankcase 39 to the head cover 42 by way of the cylinder block 40 and the cylinder head 41, a timing transmission chamber 81 which houses the cam chain 80 such that the cam chain 80 can travels therein is formed, wherein the timing transmission chamber 81 is arranged at the left side of the cylinder axis C.
In Fig. 9, in the cylinder head 41, a first support recessed portion 82 having a circular shape which houses one end portion of the camshaft 68 and a first support hole 83 which allows the camshaft 68 to pass therethrough are formed coaxially. The first support hole 83 is formed with a large diameter to an extent that the intake-side cam 72 and the exhaust-side cam 73 which are mounted on the camshaft 68 can be inserted into the first support hole 83. Further, a ball bearing 84 is interposed between an inner surface of the first support recessed portion 82 and an outer surface of one end portion of the camshaft 68, while a ball bearing 85 is interposed between an inner surface of the first support hole 83 and an outer surface of another end portion of the camshaft 68. Here, outside the ball bearing JJ-l211e/es 85, the driven sprocket 79 is fastened to another end of the camshaft 68 using a plurality of bolts 86 ... .
In one side wall of the cylinder head 41, in this embodiment, in a left side wall of the cylinder head 41 in a state that the cylinder head 41 is directed frontward in the advancing direction of the engine-assisted bicycle, a first assembling opening portion 87 is formed for enabling assembling of the camshaft 68 to the cylinder head 41 and mounting of the driven sprocket wheel 79 to the camshaft 68 from the left-side-wall side, wherein the first assembling opening portion 87 has a diameter larger than a diameter of the first support hole 83. The first assembling opening portion 87 is closed by a first lid member 88. By having the first lid member 88 threaded into a female thread 89 formed in the first assembling opening portion 87, the first lid member 88 is fixed to the cylinder head 41 and an annular sealing member 90 is sandwiched between an outer end of the first assembling opening portion 87 and the first lid member 88.
Further, in an outer surface of the first lid member 88, an engaging groove 91 with which a tool is engaged at the time of performing the rotational manipulation of the first lid member 88 is formed such that the engaging groove 91 follows a diametric line. Further, on an inner surface of the first lid member 88, a restriction projection 92 which projects toward the driven sprocket wheel 79 side is formed in a projecting manner. By bringing the driven sprocket wheel 79 inta slide contact with the restriction projection 92, the removal of the camshaft 68 toward the first assembling opening portion 87 side can be prevented.
In the cylinder head 41, a second support recessed portion 95 having a circular shape which supports one end portion of the rocker shaft 69 by making the end portion fitted thereinto and a secand support hole 96 which allows the insertion of another end portion of the rocker shaft 69 thereinto and supports the another end are coaxially formed. By having bolts 97 threaded into portions of the cylinder head 41 and the rocker shaft 69 corresponding to the second support holes 96, the rocker shaft 69 is fixedly supported on the cylinder heat 41.
Jj-22118/cs In the left side wall of th.e cylinder head 41, a second assembling opening portion 98 for enabling assembling of the rocker shaft 69 to the cylinder head 41 from the left-side-wall side is formed, wherein the second assembling opening portion 98 has a diameter substantially equal to a diameter of the second support hole 96. The second assembling opening portion 98 is closed by a second lid member 99, wherein the second lid member 99 is hermetically fitted into the second assembling opening portion 98 such that the movement thereof in the inward axial direction can be prevented. That is, the second lid member 99 having a flange portion 99a which is engaged with an outer-end periphery of the second assembling opening portion 98 at an outer end thereof is fitted into the second assembling opening portion 98 by mounting an annular sealing member 100 on the outer periphery of the second lid member 99.
Further, a notch 99b is formed in the flange portion 99a such that a portion of the first lid member 88 can be engaged with the second lid member 99 from outside. By fitting the second lid member 99 into the second assembling opening portion 98 and, thereafter, by having the first lid member 88 threaded into the first assembling opening portion 87, it is possible to simultaneously perform fixing of the first lid member 88 to the cylinder head 41 and fixing of the second lid member 99 to the cylinder head 41.
To the intake port 56 which opens in an upper side face of the cylinder head 41, an air cleaner 101 which is arranged above the power unit P and is supported on the power unit P is connected by way of a carburetor 102.
Further, to a rear end of an exhaust pipe 103 which is connected to the exhaust port 57 opened in the lower side face of the cylinder head 41 and is extended rearwardly, an exhaust muffler 104 which is arranged at the right side of the rear wheel WR is connected.
Here, secondary air for purifying exhaust air is supplied to the exhaust part 57. A lead valve 105 is provided at a right-side front portion of the head cover 42 in the engine body 38, wherein the lead valve 105 has an upstream side thereof connected with the air cleaner 101 by way of a hose not shown in the drawing and a downstream end thereof connected with the exhaust port 57 by way of a secondary air supply passage 107.
JJ-12118/cs A valve housing 108 of the lead valve 105 is constituted of a housing main portion 109 which is integrally formed with the head cover 42 and a cover 110 which is fastened to the housing main portion 109. Between the housing main portion 109 and the cover 110, a valve seat plate 113 which partitions the inside of the valve housing 108 into an upstream chamber 111 at the cover 110 side and a downstream chamber 112 at the housing main portion 109 side is sandwiched. A valve opening 114 which makes the upstream chamber 111 and the downstream chamber 112 communicate with each other is formed in the valve seat plate 113.
To a surface of the valve seat plate 113 which faces the downstream chamber 112 side, a stopper plate 115 which is spaced apart from the valve seat plate 113 at a portion thereof which faces the valve opening 114 and one end of a lead 116 which can be brought into contact with the valve seat plate 113 so to close the valve opening 114 are fastened together.
A downstream end of a hose (not shown in the drawing) is connected to a connection pipe portion 110a which is integrally formed with the above-mentioned cover 110, while an upstream end of the hose is connected to the air cleaner 101.
The secondary air supply passage 107 is configured such that a first passage portion 107a which is formed in the head cover 42 to be communicated with the downstream chamber 112 and a second passage portion 107b which is formed in the cylinder head 41 to be communicated with the exhaust port 57 are connected with each other by means of a secondary air supply pipe 117 which has an outer surface thereof exposed to the outside air. That is, a portion of the secondary air supply passage 107 is formed of the above-mentioned secondary air supply pipe 117.
On a portion of the cylinder head 41 which forms the exhaust port 57 therein, a projection portion 41b which projects downwardly is formed.
Corresponding to the projection portion 41b formed on the cylinder head 41, a lower portion of the head cover 42 is formed such that the lower portion projects downwardly from a head-cover-42-side surface of the cylinder head 41. In the head cover 42, a first passage portion 107a which Jj-12118/cs has an upstream end thereof communicated with the lower chamber of the lead valve 105 is formed such that the downstream end of the first passage portion 107a opens toward the projection portion 41b of the cylinder head 41. A second passage portion 107b is formed in the projection portion 41b of the cylinder head 41 such that an upstream end thereof opens to face the downstream-side opening end of the first passage portion 107a and a downstream end thereof opens in the exhaust port 57.
The secondary air supply pipe 117 is sandwiched between the above-mentioned projection portion 41b of the cylinder head 41 and the lower portion of the head cover 42, wherein both ends of the secondary air supply pipe 117 are fitted into the downstream-end opening portion of the first passage portion 107a and the upstream-end opening portion of the second passage portion 107b.
Between outer faces of both ends of the secondary air supply pipe 117 and the head cover 42 and the cylinder head 41 in the engine body 38, that is, between the outer faces of both ends of the secondary air supply pipe 117 and an inner face of the downstream end opening portion of the first passage portion 107a and an inner face of the upstream end opening portion of the second passage portion 107b, O-rings 118, 119 are respectively interposed. On both end portions of the secondary air supply pipe 117, enlarged-diameter portions 117a, 117b are formed for sandwiching the O-rings 118, 119 between the enlarged-diameter portions 117a, 117b and the head cover 42 and the cylinder head 41.
Here, the engine body 38 is mounted on the motorcycle in a posture that the above-mentioned secondary air supply pipe 117 are arranged to face the front side in the traveling direction of the motorcycle and, at the same time, the lead valve 105 and the first passage portion 107a which is formed in the head cover 42 while connecting the lead valve 105 and the secondary air supply passage 117 are arranged to face the front side of the traveling direction of the motorcycle. To make the traveling wind effectively impinge on the secondary air supply pipe 117, in this embodiment, the engine body 38 is mounted on the vehicle body frame 15 such that the secondary air supply pipe 117 is arranged in front of and below the engine body 38.
JJ-121is/cs To explain the embodiment in conjunction with both of Fig. 10 and Fig.
11, in the crankcase 39, an oil pump 123 which pumps oil from the lower portion in the inside of the crankcase 39 is arranged. That is, in the vicinity of a ball bearing 48 which is interposed between the case halve 39L
of the crankcase 39 and the crankshaft 37, a pump case 124 of the oil pump 123 is connected to an outer surface side of the case halve 39L.
A driven gear 126 is integrally formed with an input shaft 125 of the oil pump 123 and a driving gear 127 which is meshed with the driven gear 126 is integrally formed with the driving sprocket 78 which is fixedly mounted on the crankshaft 37 such that the driving sprocket wheel 78 constitutes a portion of the timing transmission mechanism 77. That is, the oil pump 123 performs the pumping operation in response to the rotation of the crankshaft 37. Further, the above-mentioned driving sprocket wheel 78 is arranged outside the driving gear 127 which is arranged outside the ball bearing 48.
In the case halve 39L of the crankcase 39, an intake passage 129 which has an upper end thereof contiguously connected to an intake port 128 of the oil pump 123 and extends obliquely in the vertical direction is formed and a lower-end opening portion of the intake passage 129 is closed by a plug member 130. Further, below the above-mentioned case halve 39L, a drain hole 131 for draining oil inside the crankcase 39 is formed such that the drain hole 131 intersects a portion of the intake passage 129. The drain hole 131 can be opened or closed using a drain plug 132 such that an opening end of the intake passage 129 to the drain hole 131 is not closed.
Further, above the drain plug 132 in the case halve 39L, a level display window 133 for allowing an operator to watch an oil surface in the crank case 39 is provided.
To a discharge port 135 of the oil pump 123, an oil supply passage 137 ranging from the crankcase 39 to the head cover 42 by way of the cylinder block 40 and the cylinder head 41 is communicably connected.
JJ-12118/cs The oil supply passage 137 includes an oil passage 138 which is formed in the case halve 39L such that the oil passage 138 extends from the discharge port 135 to connecting surfaces 134 of both case halves 39L, 39R, an oil passage 139 which is formed between coupling surfaces 134 of both case halves 39L, 39R and is communicated with the oil passage 138, an oil passage 140 which is formed in the crank case 39R such that the oil passage 140 extends parallel to the axis of the crankshaft 37 and is communicated with an intermediate portion of the oil passage 139, and an oil passage 141 which is formed in the cylinder block 40 and the head cover 41 such that the oil passage 141 has one end thereof communicated with another end of the oil passage 140.
The oil passage 139 is formed of an oil passage groove 142 formed in the case halve 39R facing the coupling surface 134 and the case halve 39L and is farmed in an arcuate shape such that the oil passage 139 turns around the crankshaft 37 to reach a position above the crankshaft 37.
Further, an oil injection hole 143 which injects oil to the crank pin 46 which constitutes a connecting portion of the connecting rod 45 and the crankshaft 37 and a back side of the piston 44 is formed in the crankcase 39 such that the oil injection hole 143 is communicated with the midst portion of the above-mentioned oil supply passage 137. The oil injection hole 143 is formed between the case halves 39L, 39R such that the oil injection hole 143 is communicated with the oil passage 139 in the oil supply passage 137 above the crankshaft 37. That is, the oil injection hole 143 is formed between both case halves 39L, 39R by forming a groove i n the case halve 39R along the coupling surface 134 such that the groove is communicated with the oil passage groove 142.
Further, a portion of the above-mentioned oil supply passage 137 which is communicated with the oil injection hole 143, that is, the oil passage 139 is formed in the crankcase 39 such that the oil passage 139 passes in the vicinity of the crank pin 46. The oil injection hole 143 is, as shown in Fig.
10, on a projected view to a plane orthogonal to an axis of the crankshaft 37, arranged in a range which is surrounded by a pair of vertical lines VL1, VL2 which respectively pass both left and right side ends of a rotary locus RL which a portion of the crankshaft 37 remotest from the axis of the JJ-12118/cs crankshaft 37 depicts out of an outer periphery of a large end portion 45a of the connecting rod 45, a horizontal line HL which passes the uppermost end of the rotary locus RL, and the rotary locus RL.
In the cylinder head 41 and the rocker shaft 69, to perform the lubrication between the rocker shaft 69 and the intake-side and exhaust-side rocker arms 70,71, oil passages 144, 145 which are communicated with the oil passage 141 of the above-mentioned oil supply passage 137 are formed.
Further, in the head cover 42, a plurality of oil injection holes 146 ... are formed for injecting oil toward slide contact portions between the intake-side and exhaust-side cams 72, 73 and the cam slippers 70a, 71a of the intake-side and exhaust-side rocker arms 70, 71 such that the oil injection holes 146 ... are communicated with the downstream end of the above-mentioned oil passage 141.
Further, on the head cover 42, a temperature sensor 147 which detects a temperature of the above-mentioned oil as a temperature representing the engine temperature is mounted such that the temperature sensor 147 faces the downstream portion of the oil passage 141.
Further, in a left side face of the engine body 38 at a position in front of the crankcase 39, in this embodiment, in a left side face of the cylinder block 40 behind the first lid member 88, as shown in Fig. 12, an oil injection filling port 148 for supplying oil to the inside of the crankcase 39 is formed such that the oil filling port 148 is communicated with the timing transmission chamber 81. The oil filling port 148 is closed by a replaceable oil supply cap 149.
To explain the embodiment in conjunction with Fig. 13, the power transmission device T includes a V-belt automatic transmission 155 which can automatically and variably perform gear changes of power outputted from the crankshaft 37 and a reduction gear train 156 which is provided between the V-belt automatic transmission 155 and the axle 157 of the rear wheel WR.
A case 158 of this power transmission device T is arranged at the left side of the rear wheel WR such that the case 158 is projected in the left-11-~2118/cs sideward direction from the crankcase 39. The case 158 is constituted of a case body 159 which is connected to the crankcase 39 and the cylinder block 40 and extends to the left side of the rear wheel WR, a left-side case 160 which is connected to the case body 159 such that the left-side case 160 covers the left side of the case body 159, and a right-side case 161 which is connected to the case body 159 such that the right-side case 161 covers the right side of the rear portion of the case body 159. A first transmission chamber 162 is defined between the case body 159 and the left-side case 160, while a second transmission chamber 163 is defined between a rear portion of the case body 159 and the right-side case 161. Further, a cylindrical bearing housing 164 which rotatably supports an input shaft 125 of the oil pump 123 in a cooperative manner with the above-mentioned pump case 124 is integrally mounted on the case body 159. A driven gear 126 mounted on the input shaft 125 is sandwiched by the pump case 124 and the bearing housing 144.
The V-belt automatic transmission 155 is housed in the first transmission chamber 162 and includes a driving pulley 165 which is mounted o n another end portion of the crankshaft 37, a driven pulley shaft 166 which has an axis parallel to the crankshaft 37 and is rotatably supported on the case body 159 and the right-side case 161, a driven pulley 167 which is mounted on the driven pulley shaft 166, and an endless V-belt 168 which is wound around the driving pulley 165 and the driven pulley 167.
The driving pulley 165 is constituted of a fixed pulley halve 169 which is fixed to another end portion of the crankshaft 37, a movable pulley halve 170 which is slidably supported on the crank shaft 37 such that the movable pulley halve 1.70 is capable of approaching and retracting with respect to the fixed pulley halve 169, and a centrifugal mechanism 171 which exhibits a force to push the movable pulley halve 170 to the fixed pulley halve 169 in response to the increase of a rotational speed of the crank shaft 37.
The driven pulley shaft 166 is rotatably supported on the right-side case 161 and the case body 159 by way of the ball bearings 172, 173. The driven pulley 167 includes a fixed pulley halve 174 which is relatively rotatably supported on the driven pulley shaft 166 while setting the position thereof JJ-12118/cs in the axial direction to a fixed value, and a movable pulley halve 175 which is slidably relatively rotatably supported on the fixed pulley halve 174 such that the movable pulley halve 175 is capable of approaching and retracting with respect to the fixed pulley halve 174 and is biased to the fixed pulley halve 174 side by a spring.
Further, between the fixed pulley halve 174 and the driven pulley shaft 166, a centrifugal clutch 176 which connects between the fixed pulley halve 174 and the driven pulley shaft 166 in response to the increase of rotational speed of the fixed pulley halve 174 is provided.
The reduction gear train 156 is housed in the inside of the second transmission chamber 163 and is constituted of an intermediate shaft 179 which has both end portions thereof rotatably supported on the right-side case 161 and the case body 159, a first gear 180 which is mounted on the driven pulley shaft 166, a second gear 181 which is meshed with the first gear 180 and is mounted on the intermediate shaft 179, a third gear 182 which is mounted on the intermediate shaft 179, and a fourth gear 183 which is meshed with the third gear 182. A first one-way clutch 184 is interposed between the axle 157 of the rear wheel WR and the fourth gear 183.
Here, to an outer side wall of the case halve 39R of the crankcase 39, an axle support member 185 which extends to the right side of the rear wheel WR is fastened. The axle 157 of the rear wheel WR is rotatably supported on a support sleeve portion 186 which is mounted on a rear portion of the axle support member 185, the right-side case 161 of the case 158 of the power transmission device T and the case body 159 of the case 158. That is, the axle 157 rotatably penetrates the above-mentioned support sleeve portion 186 and the right-side case 161 and enters the second transmission chamber 163, wherein a ball bearing 187 is interposed between the support sleeve portion 186 and the axle 157, a ball bearing 188 is interposed between the right-side case 161 and the axle 157, and a ball bearing 189 is interposed between the case body 159 and the axle 157.
JJ-12118/cs Further, a driven sprocket wheel 191 is mounted on an end portion of the axle 157 projected toward the outside from the support sleeve portion 18b by way of a second one-way clutch 190.
Referring to Fig. 14, in front of the engine body 38 and behind the main frame 17 of the vehicle body frame 15, a pair of left and right frame-side brackets 192, 192 which extend downwardly are fixedly mounted. On a support sleeve 193 which is arranged between both frame-side brackets 192, 192, both end portions of the pedal shaft 194 which has an axis parallel to the axle 157 of the rear wheel WR and penetrates the support sleeve 193 are rotatably supported by way of ball bearings 195, 195, while crank pedals 34 ... are fixed to both ends of the pedal shaft 194 projected from the support sleeve 193.
A driving sprocket wheel 196 is fixed to the pedal shaft 194 between the right-side crank pedal 34 and the support sleeve 193. Further, below the axle 157, a support arm 197 which is supported on the axle support member 185 is arranged such that the support arm 197 is rotatable about an axis parallel to the axle 157. A pair of sprocket wheels 198, 199 are rotatably supported on the support arm 197. Here, an endless chain 200 is wound around the driving sprocket wheel 196, the driven sprocket wheel 191 at the axle 157 side, and both sprockets 198, 199 so that the support arm 197 is biased with a spring at the side which stretches the chain 200.
That is, the chain 200 which is served for transmitting a step-in force from the crank pedals 34 ... to the rear wheel WR is arranged at the right side of the engine body 38 and a chain cover 201 which covers the chain 200 from outside is supported on the vehicle body frame 15.
In this manner, it is possible to transmit the power from the engine E to the axle 157 of the rear wheel WR by way of the power transmission device T and, at the same time, it is possible to transmit the power generated by stepping in the crank pedal 34 to the axle 157 of the rear wheel WR. Due to functions of the first and second one-way clutches 184, 190, out of the power from the engine E and the power from the crank pedal 34 ... , the power having the higher rotational speed is transmitted to the axle 157. However, when a load necessary for rotating the rear wheel JJ-l2ms/c~

-2a-WR becomes higher at the time of climbing a slope or the like, it is possible to transmit powers to the axle 157 from both of the engine E and the crank pedal 34 ... .
Here, rear-wheel brake BR is a drum brake which includes a brake drum 203 which is fixed to an axle sleeve 202 connected to the axle 157 in a relatively non-rotatable manner. The rear wheel WR includes a hub 204 which is fixed to a cylindrical support portion 203a provided to the brake drum 203 such that the hub 204 concentrically surrounds the axle sleeve 202, a rim 205 which concentrically surrounds the hub 204, a tire 206 which is mounted on the rim 205, and a plurality of wire spokes 207 .. . arranged between the hub 204 and the rim 205.
The hub 204 is constituted of a cylindrical portion 204a which is fixed to the outer periphery of the brake drum 203 by welding and a pair of flanges 204b, 204b which are integrally formed on both ends of the cylindrical portion 204a, wherein a plurality of connecting holes 208 ... which are served for engaging and connecting inner ends of respective wire spokes 207 ... are formed in both flanges 204b, 204b respectively.
In Fig. 15, front-wheel brake BF is a drum brake which includes a brake drum 213 which is fixed to an axle sleeve 212 connected to an axle 211 of the front wheel WF in a relatively non-rotatable manner. The front wheel WF includes a hub 214 which is fixed to a cylindrical support portion 213a provided to the brake drum 213 such that the hub 214 concentrically surrounds the axle sleeve 212, a rim 215 which concentrically surrounds the hub 214, a tire 216 which is mounted on the rim 215, and a plurality of wire spokes 217 ... arranged between the hub 214 and the rim 215.
The hub 214 is constituted of a cylindrical portion 214a which is fixed to the outer periphery of the brake drum 213 by welding and a pair of flanges 214b, 214b which are integrally formed on both ends of the cylindrical portion 214a, wherein a plurality of connecting holes 218 ... which are served for engaging and connecting inner ends of respective wire spokes 217 ... are formed in both. flanges 214b, 214b respectively.
JJ-12118/cs Here, the front folk 21 which supports the axle 212 of the front wheel W F
is constituted of a pair of left and right leg portions 21a, 21a which are arranged at both sides of the front wheel WF, a shaft portion 21b which is rotatably supported on the head pipe 16 and is arranged above the front wheel WF, and bridge portions 21c, 21c which connect upper portions of a lower portion of the shaft portion 21b and upper portions of the both leg portions 21a, 21a. Both ends of the axle 212 are fixed to and supported o n lower end portions of both leg portions 21a, 21a. Further, on the lower end portion of the shaft portion 21b, a front fender 219 which covers the front wheel WF from above is supported.
A front portion of the power unit P is vertically tiltably supported on the vehicle body frame 15 by way of a vibration isolating link 220. The vibration isolating link 220 includes a pair of left and right engine-side brackets 221, 221 which are mounted on a front-side lower portion of the case body 159 in the power unit P at a position offset to the left side from a vehicle body center line BC, a pair of left and right frame-side brackets 222, 222 which are fixed to the main frame 17 of the vehicle frame 15, a cylindrical rotary sleeve 223 which is arranged between the above-mentioned both engine-side brackets 221, 221, a connecting shaft 224 which is provided between both engine-side brackets 221, 221 such that the connecting shaft 224 rotatably supports the rotary sleeve 223, a link member 225 which is formed in a cylindrical shape having a transverse rectangular cross section and has one end thereof connected to the rotary sleeve 223, a cylindrical outer sleeve 226 which is arranged between the above-mentioned both frame-side brackets 222, 222 and to which another end of the link member 225 is fixed, a cylindrical inner sleeve 227 which is concentrically arranged in the inside of the outer sleeve 226, rubber bushings 229 ... which have inner peripheries thereof respectively baked to both end portions of the inner sleeve 227 and, at the same time, have outer peripheries thereof respectively baked to a cylindrical case 228 which are fitted on both end portions of the outer sleeve 226 under pressure, a tiltable support shaft 230 which is arranged between both frame-side brackets 222, 222 such that the tilfable support shaft 230 rotatably supports the inner sleeve 227, an arm 231 which is fixed to an axially intermediate portion of the outer sleeve 226 and extends to the front side, and a rubber stopper 232 which is mounted on a distal end of the arm 231.
JJ-12118/cs The rubber stopper 232 is inserted into a cylindrical contact body 234 which is fixed to the support sleeve 193 extended between both frame-side brackets 222, 222 such that both upper and lower surfaces of the rubber stopper 232 are brought into contact with upper and lower inner surfaces of the contact body 234. Further, the contact body 234 and the rubber stopper 232 are arranged at a position further offset to the left side from the vehicle body center Iine BC compared to the engine-side brackets 221, 221 and the link member 225.
With the use of such a vibration isolating link 220, a load which acts o n the tiltable support shaft 230 from the engine E of the power unit P is absorbed by the elastic deformation of the rubber bushings 229 ... and, at the same time, the rubber stopper 232 is pushed to the upper and lower inner surfaces of the contact body 234 and is elastically deformed to absorb the load. Further, since the rubber stopper 232 is brought into contact with the upper and lower inner surfaces of the contact body 234, a vertical tiltable range of the power unit P can be restricted.
To explain the embodiment in conjunction with Fig. 16, an upper portion of the power unit P and the vehicle body frame 15 are connected by a non-elastic support member 235 while allowing vertical tilting of the power unit P. Further, at a position offset to the left side from the vehicle body center line BC, to a front-side upper portion of the case body 159 in the power unit P, a bracket 236 is provided. Further, at a position offset to the left side from the vehicle body center Iine BC, between the support stay 19 and the left-side reinforcing member 20 in the vehicle body frame 15, a bracket 237 is provided.
An upper end of the support member 235 which is formed in a solid columnar form is rotatably connected to the bracket 237 at the vehicle body frame 15 side by way of a rubber bushing 238 and a connecting shaft 239 having an axis parallel to the tiltable support shaft 230 of the vibration isolating link 220, while a lower end of the support member 235 is rotatably connected to the bracket 236 at the power unit P side by way of a rubber bushing 240 and a connecting shaft 241 parallel to the connecting shaft 239.
j]-12118/cs Further, both brackets 236, 237 are respectively mounted on the power unit O and the vehicle body frame 15 such that both brackets 236, 237 are connected to each other by way of the support member 235 in front of the rear wheel WR.
Next, to explain the manner of operation of the first embodiment, in the engine E, the camshaft 68 is arranged closer to the combustion chamber 55 than the interlocking or connecting points between the intake valve 58 and the exhaust valve 59 with the intake-side and the exhaust-side rocker arms 70, 71 and, at the same time, the intake valve 58 and the exhaust valve 59 are arranged in the cylinder head 41 in a state that their open/close operating directions are arranged parallel to each other.
Accordingly, by arranging the interlocking or connecting points of intake valve 58 and the exhaust valve 59 which have their open/close operation directions arranged parallel to each other with the intake-side and exhaust-side rocker arms 70, 71 at positions close to each other, it is possible to narrow a width of the cylinder head 41.
Further, the intake port 56 which constitutes one of two ports consisting of the intake port 56 and the exhaust port 57 is formed in the cylinder head 41 such that the intake port 56 is arranged at a position remote from one end of the camshaft 68 in the axial direction such that at least a portion of the camshaft 68 is overlapped to the intake port 56 on a projected view to a plane orthogonal to the axis of the camshaft 68. Accordingly, the camshaft 68 can be arranged at a position further closer to the combustion chamber 55 side whereby the cylinder head 41 can be further miniaturized in the direction along the cylinder axis C.
Further, the intake port 56 is formed in the cylinder head 41 such that the intake port 56 intersects the rocker shaft 69 on a projected view to a plane orthogonal to the cylinder axis C, whereby the cylinder head 41 can be miniaturized in the direction along the axis of the rocker shaft 69.
Further, since the opening ends of the intake port 56 and the exhaust port 57 into the combustion chamber 55 are arranged on one straight line parallel to the axis of camshaft 68, a swirl is generated in the inside of the J1-ZZms/~s combustion chamber 55 whereby the combustion efficiency can be enhanced.
Further, an ignition plug 76 having the axis which makes an acute angle a with respect to the plane P1 including both of the axes of the intake valve 58 and the exhaust valve 59 is mounted on the cylinder head 41 and hence, it is possible to ensure a sufficient open space by obviating the arrangement of parts relevant to the intake valve 58 and the exhaust valve 59 in the periphery of the ignition plug 76 whereby a cooling wind easily impinges on the ignition plug 76 so that the ignition plug 76 can be efficiently cooled.
Here, the first assembling opening portion 87 corresponding to the camshaft 68 and the second assembling opening portion 98 corresponding to the rocker shaft 69 are formed in one side wall of the cylinder head 41 independently from each other, the second lid member 99 which closes the second assembling opening portion 98 is fitted into the second assembling opening portion 98 such that the movement of the second lid member 99 in the axially inward direction can be prevented, and the first lid member 88 is fixed to the cylinder head 41 by screwing, for example, to make the first lid member 88 engaged with an outer surface of the second lid member 99.
Accordingly, it is unnecessary for the second lid member 99 to ensure a space far mounting on a cylinder head 41 in the periphery of the second assembling opening portion 98 and hence, the distance between axes of the camshaft 68 and the rocker shaft 69 can be set to a small value thus contributing to the miniaturization of the cylinder head 41, Further, hole forming of the first support recessed portion 82 and the first support hole 83 for assembling the camshaft 68 and hole forming of the second support recessed portion 95 and the second support hole 96 for assembling the rocker shaft 96 can be performed in the same direction from one side of the cylinder head 41 whereby the cumbersome operation can be obviated thus sufficiently enhancing the forming accuracy whereby man-hours for forming can be reduced.
JJ-12118/cs Further, the secondary air supply passage 107 which supplies a secondary air to the exhaust port 57 is connected to the lead valve 105 mounted on the head cover 42 in the engine body 38, and a portion of the secondary air supply passage 107 is formed of the secondary air supply pipe 117 which has both ends thereof connected to the engine body 38 such that an outer surface thereof is exposed to outside air.
Due to such a constitution, by cooling the secondary air supply pipe 117 with air, it is possible to suppress the transfer of heat to the lead valve side. Accordingly, by providing the lead valve 105 to the head cover 42, while shortening the secondary air supply passage 107 between the lead valve 105 and the exhaust port 57, even when the engine E is of an air-cooled type, it is possible to prevent the thermally adverse influence from affecting the lead valve 105.
Further, since both ends of the secondary air supply pipe 117 are sandwiched between the cylinder head 41 and the head cover 42 which are connected to each other, connecting parts such as bands or clips which connect the secondary air supply pipe 117 to the engine body 38 become n o more necessary whereby the number of parts and man-hours for assembling can be reduced thus realizing the reduction of cost. Further, since it is unnecessary to take the space necessary for arranging connection parts into consideration, it is possible to increase the degree of freedom in designing.
Further, since the O-rings 118, 119 are respectively interposed between outer surfaces of both ends of the secondary air supply pipe 117 and the head cover 42 and the cylinder head 41, it is possible to enhance sealing ability of the connection portions between both ends of the secondary air supply pipe 117 and the head cover 42 and the cylinder head 41 by making use of an elastic force of the O-rings 118, 119 while making the enhancement of forming accuracy of both ends of the secondary air supply pipe 117 unnecessary so that the cost can be reduced by the reduction of man-hours for forming whereby the assembling operation is facilitated compared to a case in which connecting parts such as bands or clips are used.
Jj-12118/cs Further, since the engine body 38 is mounted on the motorcycle in the posture that the secondary air supply pipe 117 faces the front side in the traveling direction, the secondary air supply pipe 117 can be cooled more effectively using the traveling wind at the time of traveling of the motorcycle.
Further, the engine body 38 is mounted on the motorcycle in the posture that the lead valve 105 faces the front side in the traveling direction of the motorcycle and, at the same time, the first passage portion 107a which is formed in the head cover 42 by connecting the lead valve 105 and the secondary air supply pipe 117 faces the front side in the traveling direction of the motorcycle and hence, it is possible to further reduce the thermally adverse influence affecting the lead valve 105 by making use of a cooling effect attributed to the traveling wind.
Further, the front portion of the power unit P which includes the engine E
and the power transmission device T which transmits the output of the engine E to the rear wheel WR after speed change is vertically tiltably supported on the vehicle body frame 15 by way of the vibration isolating link 220. The rubber stopper 232 which is brought into resilient contact with the contact body 234 mounted on the vehicle body frame 15 so as to restrict the vertical tiltable range of the power unit P is formed on the vibration isolating link 220. The non-elastic support member 235 which connects the power unit P and the vehicle body frame 15 while allowing the vertical tilting of the power unit P is provided between the upper portion of the power unit P and the vehicle body frame 15.
Accordingly, by supporting the power unit P on the vehicle body frame 15 using the non-elastic support member 235 in place of the conventional rear cushion, it is possible to realize the miniaturization, the reduction of weight and the reduction of cost of the motorcycle. Further, the vertical tiltable range of the power unit P is determined based on a deflection quantity of the rubber stopper 232 which is brought into elastic contact with the contact body 234 at the vehicle body frame 15 side and hence, the space efficiency can be enhanced by restricting the vertical tiltable range of the power unit P to a relatively narrow range whereby the arrangement designing of mounting parts can be facilitated not only at the vehicle body JJ-12i IS/cs frame 15 side but also at the power unit P side and the degree of freedom in designing including aesthetic designing can be enhanced.
Further, the upper portion of the power unit P in front of the rear wheel WR and the rear portion of the vehicle body frame 15 are connected using the support member 235 and hence, the support member 235 can be shortened whereby it is possible to achieve the further reduction of weight and the further reduction of cost. Further, to the bracket 237 provided between the support stay 19 which has both end portions thereof fixedly mounted on the seat post 18 and one of reinforcing members 20 .. . which extend rearwardly and upwardly from the seat post 28 such that the reinforcing members 20 ... connect both left and right sides of the support stay 19 and the seat post 28, one end of the support member 235 is connected and hence, the power unit P can be firmly supported with such a simple structure.
Further, although oil is injected from the oil injection hole 143 to the crank pin 46 which constitutes the connecting portion between the connecting rod 45 and the crankshaft 37 and the back side of the piston 44, the oil injection hole 143 is formed in the crankcase 39 such that the oil injection hole 143 is communicated with the midst of the oil supply passage 137 formed in the engine body 38 from the crankcase 39 to the head cover 42 so as to guide the oil from the oil pomp 123 arranged in the crankcase 39.
Accordingly, in injecting the oil toward the crank pin 46 and the piston 44 side, it is sufficient to form only the oil injection hole 143 in the crankcase 39 and no specific parts are necessary whereby it is possible to inject oil using the simple and inexpensive structure and, at the same time, the reduction of weight of the engine E can be realized.
Further, the oil injection hole 143 is formed in the crankcase 39 above the crankshaft 37. Due to the injection of oil from above, it is unnecessary to set the oil injection pressure to a relatively high pressure and hence, the discharge pressure of the oil pump 123 can be made relatively low whereby the oil pump 123 can be miniaturized.
JJ-12118/cs Further, the crankcase 39 is formed by connecting a pair of case halves 39L, 39R to each other. The oil passage groove 142 is formed in at least one of both case halves 39L, 39R, that is, the case halve 39R in this embodiment, wherein the oil passage groove 142 forms the oil passage 139 which constitutes a portion of the oil supply passage 143 between coupling surfaces 134 of both case halves 39L, 39R, and oil injection hole 143 is formed between the coupling surfaces 134 of both case halves 39L, 39R
while being communicated with the oil passage groove 142. Due to such a constitution, it is possible to facilitate the forming operation which is applied to the crank case 39 for enabling the injection of the oil.
Further, a portion of the oil supply passage 137 which is communicated with the oil injection hole 143, that is, the oil passage 139 is formed in the crankcase 39 such that the oil passage 139 passes in the vicinity of the crank pin 46 and hence, the oil injection hole 143 can be arranged close to the crank pin 46 whereby the injection pressure of the oil from the oil injection hole 143 can be set to a relatively low value thus realizing the miniaturization of the oil pump 123.
Further, the oil injection hole 143 is, on the projected view to the plane orthogonal to the axis of the crankshaft 37, arranged in the range which is surrounded by a pair of vertical lines VL1, VL2 which respectively pass both left and right side ends of the rotary locus RL which a portion of the crankshaft 37 remotest from the axis of the crankshaft 37 depicts out of an outer periphery of a large end portion 45a of the connecting rod 45, the horizontal line HL which passes the uppermost end of the rotary locus RL, and the rotary locus RL. Accordingly, it is possible to inject the oil from the position close to and above the crank pin 24 and hence, the discharge pressure of the oil pump 123 can be further lowered thus realizing the miniaturization of the oil pump 123.
Here, the crankshaft 37 is rotatably supported on the crankcase 39 by way of a pair of left and right ball bearings 47, 48, and a driving sprocket wheel 78 which transmits a rotational force of the crankshaft 37 to the camshaft 68 of the valve actuating device 67 and the driving gear 127 which transmits the rotational force of the crankshaft 37 to the oil pump 123 are fixedly mounted on the crankshaft 37, wherein the driving gear 127 is arranged JJ-12118/cs outside one ball bearing 48 out of both ball bearings 47, 48, and the driving sprocket wheel 78 is further arranged outside the driving gear 127.
Accordingly, the driving sprocket wheel 78 and the driving gear 127 are arranged outside the ball bearing 48 and hence, it is not necessary to form a hermetically-closed oil chamber for every one of the driving sprocket wheel 78 and the driving gear 127 and hence, the engine E can be miniaturized in the direction along the axis of the crankshaft 37 corresponding to an amount of the oil chamber which becomes unnecessary.
Further, since the driving sprocket wheel 78 is arranged outside the driving gear 127, the cam chain 80 which is wound around the driving sprocket wheel 78 can be arranged at the position relatively remote from the cylinder bore 43 and hence, it is possible to suppress the thermal influence from the cylinder bore 43 side to the cam chain 80.
Here, the timing transmission chamber 81 is formed in the engine body 38 at the left side of the cylinder axis C which is inclined in the frontward and upward direction. In the left side face of the cylinder block 40 of the engine body 38 at the position in front of the crankcase 39, the oil injection filling port 148 which is communicated with the timing transmission chamber 81 is formed.
Here, the power transmission device T is housed in the inside of the case 158 which is arranged at the left side of the rear wheel WR such that the case 158 is projected left sideward from the crankcase 39, and the left-side face of the cylinder block 40 in front of the crankcase 39 is arranged at a position which is inwardly recessed than the case 158. Accordingly, by forming the oil filling port 148 in the cylinder block 40 at the position which is inwardly recessed than the case 158, it is possible to prevent the large-sizing of the engine body 38 in the direction along the axis of the crankshaft 37 and, at the same time, it is possible to arrange the oil filling port 148 by obviating the interference of the oil filling port 148 with parts which are present in the periphery of the engine body 38. Further, the timing transmission chamber 81 with which the oil filling port 148 is communicated is inclined such that a crankcase 39 side thereof assumes a Jl-2211s/c~

lower position corresponding to the front upward inclination of the engine body 38 and hence, it is possible to make the oil which is filled into the timing transmission chamber 81 flow from the oil filling port 148 toward the crankcase 39 side.
Further, at the rear wheel WR and the front wheel WF, the hubs 204, 214 are formed such that a pair of flanges 204b, 204b; 214b, 214b to which a plurality of wire spokes 207 ... , 217 ... are connected are integrally provided.
Accordingly, compared to a wheel in which a hub is constituted of a plurality of members, it is possible to solve a problem of rust caused by the intrusion of water into coupling surfaces of the plurality of members.
Further, since the hubs 204, 214 are integrally formed by molding, positioning of a welding jig at the time of welding both flanges 204b, 204b;
214b, 214b to the cylindrical support portions 203a, 213a can be completed by merely performing positioning with respect to the hubs 204, 214 whereby man-hours for forming can be reduced. Further, by integrally forming the hubs 204, 214 by molding, it is easy to ensure the positional accuracy of the connecting holes 208 ..., 218 ... which are formed in both flanges 204b, 204b; 214b, 214b such that connecting holes 208 ..., 218 ...
face each other in the axial directions of the axles 157, 212.
Fig. 17 shows the second embodiment of the present invention, wherein an oil injection hole 143' which injects the oil to the crank pin 46 which constitutes the connection portion between the connecting rod 45 and the crankshaft 37 and the back side of the piston 44 is formed in the case halve 39R of the crank case 39 such that the oil injection hole 143' is communicated with the midst of the oil supply passage 137 which introduces the oil from the oil pump 123. The oil injection hole 143°
is formed in the case halve 39R such that the oil injection hole 143' is communicated with the oil passage 140 in the oil supply passage 137 above the crankshaft 37.
Also in this second embodiment, in the same manner as the first embodiment, in injecting the oil toward the crank pin 46 and the piston 44 side, it is sufficient to form only the oil injection hole 143 in the crankcase 39 and no specific parts are necessary whereby it is possible to inject oil with the simple and inexpensive structure and, at the same time, the JJ-12118/cs reduction of weight of the engine E can be realized. Further, due to the injection of oil from above, it is unnecessary to set the oil injection pressure to a relatively high pressure and hence, the discharge pressure of the oil pump 123 can be made relatively low whereby the oil pump 123 can be miniaturized.
Fig. 18 shows the third embodiment of the present invention, wherein a plurality of, for example, a pair of oil injection holes 143, 143 which inject the oil to the crank pin 46 and the back side of the piston 44 are formed i n the crankcase 39 such that these oil injection holes 143, 143 are communicated with the midst of the oil supply passage 137. These oil injection holes 143, 143 are formed between the case halves 39L, 39R such that they are communicated with the oil supply passage 139 in the oil passage 137.
According to third embodiment, besides the advantageous effects achieved by the first embodiment, it is possible to lubricate a portion covering a wide range including the crank pin 46 and the piston 44 with the simple structure.
Fig. 19 and Fig. 20 show the fourth embodiment of the present invention, wherein Fig. 19 is a cross-sectional view corresponding to Fig. 5 of the first embodiment and Fig. 20 is an enlarged cross-sectional view taken along a line 20-20 in Fig. 19.
Between the camshaft 68 and the crankshaft 37, a timing transmission mechanism 247 which transmits a rotational force of the crankshaft 37 to the camshaft 68 at a reduction gear ratio of 1/2 is provided. The timing transmission mechanism 247 is constituted by winding an endless timing belt 250 to a driving pulley 248 which is fixed to the crankshaft 37 outside the driving gear 127 and a driven pulley 249 which is fixed to the camshaft 68, wherein a portion of the timing belt 250 which extends from the crank case 39 to the head cover 42 by way of the cylinder block 40 and the cylinder head 41 is accommodated in a travelling manner in the timing transmission chamber 81 which is formed in the engine body 38.
JJ-12118/ cs Also with this fourth embodiment, it is possible to obtain advantageous effects substantially equal to those of the above-mentioned respective embodiments.
Here, since the timing transmission chamber 81 is inclined such that the crankcase 39 side assumes the lower position, the oil from the cylinder head 41 smoothly returns to the crankcase 39 side by way of the timing transmission chamber 81. Accordingly, the oil hardly adheres to the timing belt 250 so that a lifetime of the timing belt 250 can be prolonged.
Further, it is possible to reduce the adhesion of oil to a winding portion of the timing belt 250 around the driving pulley 248 and the driven pulley 249 so that the friction can be reduced.
Although the embodiments of the present invention have been explained heretofore, the present invention is not limited to the above-mentioned embodiments and various design variations can be made without departing from the invention described in claims.
As has been explained heretofore, according to the present invention, positioning of the welding jig at the time of welding the hub to the cylindrical support portion of the support member is facilitated. Further, it is possible to easily ensure the positional accuracy of the connection holes formed in both flanges due to the accuracy control of the hub as a single product and hence, it is possible to realize the reduction of cost by reducing man-hours for manufacturing.
Although various preferred embodiments of the present invention have been described herein in detail, it will be appreciated by those skilled in the art, that variations may be made thereto without departing from the spirit of the invention or the scope of the appended claims.
JJ-12118/cs

Claims

1. A wheel for a bicycle comprising an axle supporting a rotary axle sleeve;
a support member fixedly attached to said axle sleeve;
said support member including a cylindrical support portion radially spaced from and concentrically surrounding said axle sleeve;
a hub including a cylindrical portion fixedly mounted on an outer periphery of said cylindrical support portion of said support member, said hub including a pair of radially extending flanges extending from opposite ends of the cylindrical portion and integral therewith;
said flanges including connection holes engaging wire spokes extending between said flanges and a rim supporting a tire; and wherein said hub is fixedly secured to said axle sleeve by said support member.

2. A wheel for a bicycle as claimed in Claim 1 wherein said support member forms a brake drum.

3. A wheel for a bicycle as claimed in Claim 1 wherein said support member includes a radially extending flange connecting one of said cylindrical support portion to said axle sleeve.

4. A wheel for bicycle as claimed in Claims 1 or 2 wherein said cylindrical support portion is connected to said axle sleeve to define a cantilevered support of said cylindrical support portion.

5. A wheel for a bicycle as claimed in claim 1, 2, or 3 wherein said rim, said hub, said cylindrical support portion and said axle sleeve are aligned with respect to a vertical section through said rim.

6. A wheel for a bicycle as claimed in Claims 1, 2, 3, 4 or 5 wherein said support member is welded to said axle sleeve.

7. A wheel a bicycle as claimed in Claims 1, 2, 3, 4, 5 or 6 wherein said cylindrical support portion and said cylindrical portion of said hub are welded one to the other.