JP6256068B2 - Gear support structure for cam gear train mechanism of motorcycle - Google Patents

Description

  The present invention relates to a gear support structure for a cam gear train mechanism of a motorcycle.

  There is known a motorcycle including a so-called cam gear train mechanism that transmits a driving force of a crankshaft to a camshaft of a valve operating mechanism via a plurality of gears.

  In a conventional motorcycle, cam gears are attached to each of a crankcase, a cylinder, and a cylinder head, and then covered with a cover (see, for example, Patent Document 1).

JP-A-3-260302

  From the viewpoint of lubricating the cam gear of the cam gear train mechanism, the housing portion for accommodating the cam gear is formed with a hollow portion in each of the crankcase, the cylinder, and the cylinder head, and the cam gear train mechanism is provided in the housing portion that is integrally connected to these hollow portions. It is preferable to pay.

  On the other hand, when the housing portion is integrated with the crankcase, the cylinder, and the cylinder head, a gear shaft that supports the cam gear must be provided inside the housing portion. If it does so, the seat surface which fixes a gear shaft must be provided in the inside of a housing part, and also the hole for processing a seat surface is required for the side wall of a crankcase, a cylinder, and a cylinder head.

  Also, the holes made in the crankcase, cylinder, and cylinder head for machining the seating surface will reduce the strength of the crankcase, cylinder, and cylinder head if they are opened large, while if they are opened small, the rotation center line direction In addition, the contact area between the thrust washer that supports the cam gear and the crankcase, the cylinder, and the cylinder head is reduced to reduce the wear resistance at the contact portion.

  SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a gear support structure for a cam gear train mechanism of a motorcycle that improves wear resistance at a contact portion between a crankcase, a cylinder and a cylinder head and a thrust washer without impairing productivity. And

  In order to solve the above problems, a gear support structure for a cam gear train mechanism of a motorcycle according to the present invention includes a crankcase, a crankshaft accommodated in the crankcase, and a cylinder provided in the crankcase and defining a cylinder bore. A cylinder head connected to the cylinder, a valve operating device having a camshaft for intake and exhaust to the cylinder bore and housed in the cylinder head, and a driving force from the crankshaft to the camshaft. A cam power transmission mechanism for transmitting, and the crankcase, the cylinder, and the cylinder head each include a housing portion that accommodates the cam power transmission mechanism, and the cam power transmission mechanism A plurality of gears meshed with each other, and a plurality of gears rotatably supporting each gear. A gear shaft, inserted into each of the gear shafts, and sandwiched between at least one of the gears and the crankcase, the cylinder, or the cylinder head to support the gear in the axial direction of the gear shaft A plurality of thrust washers that are disposed on either side of the crankcase, the cylinder, and the cylinder head from a first end portion disposed on the gear side. The inner diameter of the end is smaller.

  ADVANTAGE OF THE INVENTION According to this invention, the gear support structure of the cam gear train mechanism of the motorcycle which improves abrasion resistance in the contact part of a crankcase, a cylinder, a cylinder head, and a thrust washer can be provided, without impairing productivity.

1 is a right side view showing a motorcycle to which a cam gear support structure according to an embodiment of the present invention is applied. The right view which shows an engine provided with the gear support structure which concerns on embodiment of this invention. The right view which shows a cam gear train mechanism provided with the gear support structure which concerns on embodiment of this invention by notching a cylinder block, a cylinder head, and a head cover partially. Sectional drawing which shows the gear support structure which concerns on embodiment of this invention. Sectional drawing which shows the gear support structure which concerns on embodiment of this invention. The perspective view which shows the thrust washer of the gear support structure which concerns on embodiment of this invention. Sectional drawing which shows the other example of the thrust washer of the gear support structure which concerns on embodiment of this invention.

  An embodiment of a cam gear support structure for a motorcycle according to the present invention will be described with reference to FIGS.

  FIG. 1 is a right side view showing a motorcycle to which a cam gear support structure according to an embodiment of the present invention is applied.

  In the present embodiment, front and rear, top and bottom, and left and right expressions are based on the rider who rides the motorcycle 1.

  As shown in FIG. 1, a motorcycle 1 according to this embodiment includes a body frame 2 that extends in the front-rear direction, an engine 3 that is suspended from the body frame 2, and a front end portion of the body frame 2 that is steered in the left-right direction. A steering mechanism 5 that is supported, a front wheel 6 that is rotatably supported at the lower end of the steering mechanism 5, a front wheel suspension device 7 that cushions an impact transmitted from the front wheel 6 to the vehicle body frame 2 and grounds the front wheel 6. A swing arm 8 supported by a lower end portion of the body frame 2 so as to be swingable in the vertical direction, a rear wheel 11 supported rotatably at a rear end portion of the swing arm 8, a body frame 2 and the swing arm 8. And a rear wheel suspension device 12 for buffering an impact transmitted from the rear wheel 11 to the vehicle body frame 2 and for grounding the rear wheel 11.

  The vehicle body frame 2 is, for example, a twin tube type frame. The vehicle body frame 2 includes a steering head pipe 13 at the top of the front end, a pair of left and right main frames 15 that branch right and left immediately after the steering head pipe 13 and extend obliquely downward and downward, and a rear end of the main frame 15. And a pair of left and right center frames 16 extending downward.

  The steering head pipe 13 supports the steering mechanism 5 so as to be steerable in the left-right direction of the vehicle. The steering head pipe 13 is tilted backward according to the caster angle of the steering mechanism 5.

  The main frame 15 branches immediately after the steering head pipe 13 and extends while inclining gently downward and rearward of the vehicle while expanding in the left-right direction of the vehicle. The main frame 15 also serves as a tank rail, and supports an air cleaner box 18 disposed above the front half from below, and supports a fuel tank 19 disposed above the rear half from below. The main frame 15 supports the engine 3 disposed below so as to be suspended.

  The center frame 16 holds a pivot shaft 21 extending in the vehicle width direction. The pivot shaft 21 is a swing center that supports the swing arm 8.

  The engine 3 is disposed behind the front wheel 6 and below the main frame 15 and occupies the lower center of the motorcycle 1.

  The steering mechanism 5 is provided in the vicinity of the upper end of each front fork 22, a steering shaft (not shown) that is the rotation center of the steering mechanism 5 and penetrates the steering head pipe 13, a pair of left and right front forks 22 that extend vertically. A pair of left and right handle bars 23, a handle grip 25 at the free end of the handle bar 23, and a front fender 26 covering the front wheel 6 are provided. The handle grip 25 on the right side of the motorcycle 1 is a throttle grip 27.

  In addition, the motorcycle 1 includes a streamlined cowling 28 that covers the vehicle body frame 2 from at least a part of the vehicle, for example, from the front to the lower center. The cowling 28 reduces air resistance during traveling of the motorcycle 1 and protects the rider from traveling wind pressure. The cowling 28 includes a front cover 29 that covers the front of the vehicle, a pair of left and right side covers 31 that cover the sides of the engine 3, an air cleaner cover 32 that covers the air cleaner box 18, and a seat cover that supports the seat 33 on which the rider sits. 35 and a rear cover 36 that covers the rear of the vehicle.

  The fuel tank 19 is connected to the rear portion of the air cleaner box 18, extends rearward, and lies under the seat 33.

  Next, the cam gear train mechanism 41 of the motorcycle 1 according to this embodiment will be described in detail.

  FIG. 2 is a right side view showing an engine provided with a gear support structure according to an embodiment of the present invention.

  FIG. 3 is a right side view showing a cam gear train mechanism provided with a gear support structure according to an embodiment of the present invention by partially cutting a cylinder block, a cylinder head, and a head cover.

  As shown in FIGS. 2 and 3, the engine 3 according to this embodiment is a four-cycle engine, specifically, a four-cycle in-line four-cylinder engine. The engine 3 includes a cylinder block 42, a cylinder head 43 coupled to the cylinder block 42, a head cover 45 coupled to the cylinder head 43, an oil pan 46 provided below the cylinder block 42, and a rear portion of the cylinder block 42. And a clutch mechanism 47 provided on the vehicle. The engine 3 may be a multi-cylinder engine other than four cylinders or a single cylinder engine.

  The cylinder block 42 is integrally provided with a crankcase 48 and a cylinder 49. The cylinder block 42 includes an upper block 53 and a lower block 55 that can be divided into two by a dividing surface 52 that extends obliquely upward and rearward through the rotation center line of the crankshaft 51. The engine 3 may include the crankcase 48 and the cylinder 49 as separate parts.

  The upper block 53 is integrally provided with an upper half portion of the crankcase 48 and a cylinder 49 that partitions the cylinder bore 56. The cylinder 49 tilts the center line of the cylinder bore 56 slightly forward from the upright position. A piston (not shown) is slidably accommodated in the cylinder bore 56.

  The lower block 55 defines the lower half of the crankcase 48.

  The cylinder head 43 is connected to the top of the cylinder 49 and defines a combustion chamber (not shown) connected to the cylinder bore 56. The piston in the cylinder bore 56 reciprocates by the combustion of the air-fuel mixture that occurs periodically in the combustion chamber.

  The oil pan 46 is connected to the lower part of the lower block 55. The oil pan 46 stores engine oil that circulates through each part of the engine 3.

  The clutch mechanism 47 is a dry clutch. The clutch mechanism 47 is partially obscured by a clutch cover 57 assembled to the side wall of the cylinder block 42.

  The cylinder block 42, the cylinder head 43, and the head cover 45, or the crankcase 48, the cylinder 49, the cylinder head 43, and the head cover 45 are integrally provided with a housing portion 61 that houses a cam gear train mechanism 41 as a cam power transmission mechanism. Is partitioned.

  The housing part 61 is provided on one side of the engine 3, here on the right side.

  The cam gear train mechanism 41 transmits driving force from the crankshaft 51 to the camshaft 62. The cam gear train mechanism 41 includes a plurality of gears 65 that are meshed with each other and a plurality of gear shafts 66 that rotatably support the respective gears 65.

  The plurality of gears 65 include a crank gear 67 provided integrally with the crankshaft 51, a front idle gear 68 meshed with the crank gear 67, a middle idle gear 69 meshed with the front idle gear 68, and a middle gear. A rear stage idle gear 71 meshed with the idle gear 69 and a plurality of cam gears 72 that are rotatably integrated with the camshaft 62 and meshed with the rear stage idle gear 71 are included. The plurality of cam gears 72 are a cam gear 72a provided on the intake-side cam shaft 62a and a cam gear 72b provided on the exhaust-side cam shaft 62b.

  The plurality of gear shafts 66 includes a front gear shaft 73 that rotatably supports the front idle gear 68, a middle gear shaft 74 that rotatably supports the middle idle gear 69, and a rear gear shaft 75 that rotatably supports the rear idle gear 71. And. The front gear shaft 73 is provided at a portion corresponding to the cylinder block 42, particularly the upper half of the crankcase 48, and supports the front idle gear 68. The middle gear shaft 74 is provided in a portion corresponding to the cylinder block 42, particularly the cylinder 49, and supports the middle idle gear 69. The rear gear shaft 75 is provided on the cylinder head 43 and supports the rear gear shaft 75.

  Further, the plurality of gear shafts 66 are formed on the side walls of the engine 3 that define the housing portion 61, that is, the side walls of the cylinder block 42 and the cylinder head 43, or the side walls of the crankcase 48, the cylinder 49, and the cylinder head 43. Each of the openings 77 passes through the housing portion 61 to support the plurality of gears 65. The plurality of gear shafts 66 also serve as lids that close the openings 77.

  FIG. 4 is a cross-sectional view showing a gear support structure according to an embodiment of the present invention.

  FIG. 5 is a cross-sectional view showing a gear support structure according to an embodiment of the present invention.

  FIG. 6 is a perspective view showing a thrust washer of the gear support structure according to the embodiment of the present invention.

  As shown in FIGS. 4 to 6, the cam gear train mechanism 41 according to the present embodiment is inserted into the gear shaft 66 and sandwiched between at least one of the gears 65 and the cylinder block 42 and the cylinder head 43. Alternatively, a plurality of thrust washers 79 that are sandwiched between at least one of the gears 65 and any of the crankcase 48, the cylinder 49, and the cylinder head 43 and support the gear 65 in the axial direction of the gear shaft 66 are provided. .

  The plurality of thrust washers 79 includes a front-stage thrust washer 81 sandwiched between the front-stage idle gear 68 and the cylinder block 42, particularly a portion corresponding to the upper half of the crankcase 48, a middle-stage idle gear 69, and the cylinder block 42. A middle thrust washer 82 sandwiched between a portion corresponding to the cylinder 49 of the crankcase 48 and a rear thrust washer (not shown) sandwiched between the rear idle gear 71 and the cylinder head 43 are included.

  Each of the plurality of thrust washers 79 has a second end portion 84 disposed on one side of the crankcase 48, the cylinder 49, and the cylinder head 43 rather than the first end portion 83 disposed on the gear 65 side. Small inner diameter. Each of the plurality of thrust washers 79 has an inner diameter gradually decreasing portion 86 whose inner diameter is smaller toward a position closer to any one of the crankcase 48, the cylinder 49, and the cylinder head 43.

  On the other hand, the gear shaft 66 has an outer diameter gradually decreasing portion 87 whose outer diameter is smaller as it is closer to either the crankcase 48, the cylinder 49, or the cylinder head 43 following the inner diameter gradually decreasing portion 86 of the thrust washer 79. Yes.

  The tip of the outer diameter gradually decreasing portion 87 is disposed at a position closer to either the crankcase 48, the cylinder 49, or the cylinder head 43 than the portion where the inner diameter gradually decreasing portion 86 of the thrust washer 79 starts to decrease the inner diameter.

  In the cam gear train mechanism 41, the front idle gear 68, the front gear shaft 73, the front thrust washer 81, the middle idle gear 69, the middle gear shaft 74, and the middle thrust washer 82, the rear idle gear 71, the rear gear shaft 75, and Since the rear thrust washer also has a similar gear support structure, the middle idle gear 69, the middle gear shaft 74, and the middle thrust washer 82 are representatively omitted and the others are omitted.

  That is, in the middle thrust washer 82, the inner diameter of the second end 84 disposed on the cylinder 49 side is smaller than the first end 83 disposed on the middle idle gear 69 side. The tip of the second end portion 84 is in contact with an annular seat surface 89 formed on the inner wall 88 of the cylinder 49. The middle thrust washer 82 has an inner diameter gradually decreasing portion 86 whose inner diameter is smaller toward the cylinder 49 side. The inner diameter gradually decreasing portion 86 increases the contact area between the second end portion 84 of the middle thrust washer 82 and the seating surface 89 of the cylinder 49 as compared with a thrust washer having a uniform inner diameter. The inner diameter gradually decreasing portion 86 may or may not reach the second end portion 84 of the middle thrust washer 82. The outer diameter of the second end portion 84 of the middle thrust washer 82 is substantially the same as the outer dimension of the annular seat surface 89.

  The middle gear shaft 74 has an outer diameter gradually decreasing portion 87 whose outer diameter is smaller as the position is closer to the cylinder 49 side, following the inner diameter gradually decreasing portion 86 of the middle thrust washer 82.

  The tip of the outer diameter gradually decreasing portion 87 is disposed at a position closer to the cylinder 49 side than the portion where the inner diameter gradually decreasing portion 86 of the middle thrust washer 82 begins to decrease the inner diameter.

  The cylinder 49 that defines the housing portion 61 includes a cylindrical seating surface 91 that fixes the middle gear shaft 74. The cylindrical seat surface 91 is disposed concentrically inside the annular seat surface 89. The annular seat surface 89 and the cylindrical seat surface 91 are formed on the inner wall 88 of the housing portion 61 using an opening 77 that is closed by the middle gear shaft 74. That is, the opening 77 is used for the purpose of causing the tool to reach the inner wall 88 of the housing portion 61 when the seating surfaces 89 and 91 are formed. For this reason, the seating surface 89 and the seating surface 91 are formed below the diameter dimension of the opening 77. The seat surface 91 is provided with a bolt hole 93 for fastening a bolt 92 for fixing the middle gear shaft 74.

  The middle gear shaft 74 includes a cup-shaped inner end portion 95 that is fitted onto the seating surface 91, an outer end portion 96 that is fitted into the opening 77, and a journal portion 97 that supports the middle-stage idle gear 69. The inner end portion 95 has a plurality of, for example, three fixing holes 99 in a cup-shaped bottom plate portion 98. The middle gear shaft 74 is fixed by a bolt 92 that is fastened to the bolt hole 93 of the seating surface 91 from the outer end 96 through the fixing hole 99. An annular seal member 101 is provided between the outer end portion 96 and the opening 77 to prevent leakage of lubricating oil from the housing portion 61. The journal portion 97 rotatably supports the middle idle gear 69 via the bearing 102. There is a step between the journal portion 97 and the outer end portion 96. This step cooperates with the middle thrust washer 82 to sandwich the bearing 102 and the middle idle gear 69.

  The first end portion 83 of the middle thrust washer 82 is provided with a hook-like portion 103 that sandwiches the bearing 102 and the middle idle gear 69 together with the step of the middle gear shaft 74 and bears the thrust load of the middle idle gear 69. The hook-shaped portion 103 extends outward in the radial direction of the inner end portion 95 of the middle gear shaft 74.

  FIG. 7 is a cross-sectional view showing another example of the thrust washer of the gear support structure according to the embodiment of the present invention.

  The thrust washer 79 of the cam gear train mechanism 41 according to the present embodiment has a stepped inner diameter as shown in FIG. 7 instead of the inner diameter gradually decreasing portion 86 where the inner diameter gradually decreases linearly as shown in FIGS. You may provide the level | step difference part 86A which changes.

  According to the gear support structure of the cam gear train mechanism 41 according to the present embodiment configured as described above, the contact surface between the thrust washer 79 and any of the crankcase 48, the cylinder 49, and the cylinder head 43 serves as the diameter of the thrust washer 79. Widening inward, the contact area between the thrust washer 79 and the seating surface 89 is increased, while the opening 77 formed in the side wall of the crankcase 48, the cylinder 49, or the cylinder head 43 is enlarged. This is not necessary, and a reduction in the strength of the crankcase 48, the cylinder 49, and the cylinder head 43 can be avoided while maintaining productivity.

  Further, according to the gear support structure of the cam gear train mechanism 41 according to the present embodiment, the contact area between the thrust washer 79 and any of the crankcase 48, the cylinder 49, and the cylinder head 43 is increased, and the annular seat surface 89 is formed. Abrasion resistance can be increased.

  Furthermore, according to the gear support structure of the cam gear train mechanism 41 according to the present embodiment, the thrust washer 79 and the crankcase 48 are inserted by inserting the outer diameter gradually decreasing portion 87 of the gear shaft 66 into the inner diameter gradually decreasing portion 86 of the thrust washer 79. The projecting length of the inner end portion 95 of the gear shaft 66 can be increased while increasing the contact area with either the cylinder 49 or the cylinder head 43, and the seat of any of the crankcase 48, the cylinder 49, and the cylinder head 43 can be increased. By securing a longer fitting length in the axial direction of the inner end portion 95 of the gear shaft 66 that is fitted on the surface 91, the positioning of the gear shaft 66 with respect to the crankcase 48, the cylinder 49, and the cylinder head 43 can be ensured. .

  Furthermore, according to the gear support structure of the cam gear train mechanism 41 according to the present embodiment, by inserting the outer diameter gradually decreasing portion 87 of the gear shaft 66 into the inner diameter gradually decreasing portions 86, 86A of the thrust washer 79, the crankcase 48, the cylinder 49 and the seat surface 91 that fixes the gear shaft 66 to any one of the cylinder heads 43 can be reduced, and the seat surface 89 between the thrust washer 79 and the crankcase 48, the cylinder 49, or the cylinder head 43 can be widened. it can.

  Therefore, according to the cam gear train mechanism 41 according to the present embodiment, the wear resistance at the contact portion between the crank case 48, the cylinder 49 and the cylinder head 43 and the thrust washer 79 is improved without impairing the productivity.

1 Motorcycle 2 Body frame 3 Engine 5 Steering mechanism 6 Front wheel 7 Front wheel suspension device 8 Swing arm 11 Rear wheel 12 Rear wheel suspension device 13 Steering head pipe 15 Main frame 16 Center frame 18 Air cleaner box 19 Fuel tank 21 Pivot shaft 22 Front fork 23 Handlebar 25 Handle grip 26 Front fender 27 Throttle grip 28 Cowling 29 Front cover 31 Side cover 32 Air cleaner cover 33 Seat 35 Seat cover 36 Rear cover 41 Cam gear train mechanism 42 Cylinder block 43 Cylinder head 45 Head cover 46 Oil pan 47 Clutch mechanism 48 Crank Case 49 Cylinder 51 Crankshaft 52 Dividing surface 53 Upper block 55 Lower Lock 56 Cylinder bore 57 Clutch cover 61 Housing parts 62, 62a, 62b Cam shaft 65 Gear 66 Gear shaft 67 Crank gear 68 Front idle gear 69 Middle idle gear 71 Rear idle gears 72, 72a, 72b Cam gear 73 Front gear shaft 74 Middle gear shaft 75 Rear gear shaft 77 Opening 79 Thrust washer 81 Front thrust washer 82 Middle thrust washer 83 First end 84 Second end 86 Inner diameter gradually decreasing portion 86A Stepped portion 87 Outer diameter gradually decreasing portion 88 Inner wall 89 Seat surface 91 Seat surface 92 Bolt 93 Bolt hole 95 Inner end portion 96 Outer end portion 97 Journal portion 98 Bottom plate portion 99 Fixing hole 101 Seal member 102 Bearing 103 Saddle-shaped portion

Claims (2)

A crankcase,
A crankshaft housed in the crankcase;
A cylinder provided in the crankcase and defining a cylinder bore;
A cylinder head coupled to the cylinder;
A valve operating device having a camshaft for intake and exhaust to the cylinder bore and housed in the cylinder head;
A cam power transmission mechanism that transmits a driving force from the crankshaft to the camshaft,
The crankcase, the cylinder, and the cylinder head are integrally partitioned with a housing portion that houses the cam power transmission mechanism,
The cam power transmission mechanism includes a plurality of gears meshed with each other, a plurality of gear shafts rotatably supporting the respective gears, and at least one of the gears and the crank inserted into each of the gear shafts. A plurality of thrust washers sandwiched between any of the case, the cylinder, and the cylinder head and supporting the gear in the axial direction of the gear shaft;
The thrust washer is a motorcycle having a smaller inner diameter at the second end portion disposed on either the crankcase, the cylinder, or the cylinder head than the first end portion disposed on the gear side. Gear support structure for cam gear train mechanism. The thrust washer has an inner diameter gradually decreasing portion whose inner diameter is smaller toward a position closer to any side of the crankcase, the cylinder, and the cylinder head,
The gear shaft has an outer diameter gradually decreasing portion whose outer diameter is smaller toward a position closer to one of the crankcase, the cylinder, and the cylinder head following the inner diameter gradually decreasing portion of the thrust washer,
2. The tip of the outer diameter gradually decreasing portion is disposed at a position closer to either the cylinder or the cylinder head than a portion where the inner diameter gradually decreasing portion of the thrust washer starts to decrease the inner diameter. Support structure for cam gear train mechanism of motorcycles.

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