BRIEF DESCRIPTION OF THE DRAWINGS
The above and other objects, features and advantages of the present invention will become more apparent from the following description taken in connection with the accompanying drawings, in which:
FIG. 1 is a left side view of a saddle-type four wheeled vehicle on which an engine for vehicle according to the present invention is mounted;
FIG. 2 is a left side view of the engine of the vehicle of FIG. 1 from which part of a generator cover is cut off;
FIG. 3 is a longitudinal right side view of the engine of FIG. 2;
FIG. 4 is a developed view in section taken along line IV-IV of FIG. 2;
FIG. 5 is a developed view in section taken along line V-V of FIG. 3;
FIG. 6 is an enlarged view near a starting motor of FIG. 5;
FIG. 7 is a left side view of FIG. 6; and
FIG. 8 is a longitudinal sectional view of a related art.
DESCRIPTION OF THE PREFERRED EMBODIMENT
FIGS. 1 to 7 show an engine for vehicle according to the present invention and a saddle-type four wheeled vehicle on which the engine is mounted. An embodiment of the present invention will be described with reference to these drawings. In this case, in a concept of directions used for the following description, a front side as seen from a rider riding on the vehicle shown in FIG. 1, that is, a direction in which the vehicle moves forward is called a front side of the vehicle and each of constituting elements of the vehicle, except as otherwise specified.
[Entire Structure of the Straddle-Type Four Wheeled Vehicle]
FIG. 1 is a left side view of the straddle-type four wheeled vehicle. A pair of left and right front wheels 2 are supported by a front portion of a body frame 1 of the vehicle. A pair of left and right rear wheels 3 are supported by a rear portion of the body frame 1 via a swing arm 4. An engine E is mounted in a space between the front wheels 2 and the rear wheels 3. The body frame 1 has, in its upper portion, a steering wheel device 7 for steering the vehicle, a fuel tank 8 and a seat 9 for the rider, in this order from the front side. The engine E of this embodiment is a single cylinder engine. A body of the engine E is composed of a crankcase 10, a cylinder block 11 fastened to a upper surface in a front portion of the crankcase 10, a cylinder head 12 fastened to an upper surface of the cylinder 11 and a cylinder head cover 13 fastened to an upper surface of the cylinder head 12. A pair of front and rear cam shafts for driving intake and exhaust valves 14 are arranged on an upper end of the cylinder head 12. The cam shafts 14 are coupled to a crankshaft 20 by a chain transmission mechanism (not shown). A chain tensioner 15 for giving tension to a chain of the chain transmission mechanism is provided on the rear surface of the cylinder block 11 so as to be protruded rearward. A generator cover 16 is attached to a left side surface of the crankcase 10. A starting motor 18 is arranged above a top wall of the crankcase 10 and near the rear surface of the cylinder block 11. The starting motor 18 is positioned below the chain tensioner 15.
[Entire Configuration of the Engine]
FIG. 2 is a left side view of the engine E from which a part of the generator cover 16 is cut off. FIG. 3 is a right side view of the engine E. FIG. 4 is a developed view in section taken along line IV-IV of FIG. 2. FIG. 5 is a developed view in section taken along line V-V of FIG. 3.
In FIG. 3, a front half portion of the crankcase 10 has a crank chamber 21 for housing the crankshaft 20. A rear half portion of the crankcase 10 has a gear transmission chamber 23 for housing a gear transmission 22. The crank chamber 21 and the gear transmission chamber 23 are partitioned by a partition wall 24.
The gear transmission 22 includes an input shaft 26 provided with input shift gears 25, an output shaft 28 provided with output shift gears 27, a reverse idle shaft 31 provided with a reverse idle gear 29 for rearward movement of the vehicle and a change drum 32 for shift the gear transmission 22. The output shaft 28 is arranged in a rear portion of the gear transmission chamber 23. An axis O2 of the output shaft 28 is positioned slightly above an axis O1 of the crankshaft 20. The input shaft 26 and the reverse idle shaft 31 are arranged in a space between the output shaft 28 and the partition wall 24 in a forward and rearward direction of the vehicle.
Provided that a line connecting the axis O1 of the crankshaft 20 and the axis O2 of the output shaft 28 is referred as a reference line M of a layout of the shafts, an axis O3 of the input shaft 26 and an axis O4 of the reverse idle shaft 31 are positioned so as to be substantially symmetric with respect to the reference line M. The change drum 32 is arranged in such a manner that an axis O7 of the change drum 32 is positioned rearwardly and downwardly of the axis O4 of the reverse idle shaft 31 and is positioned forwardly and downwardly of the axis O2 of the output shaft 28.
In FIG. 5, the crankcase 10 is divided into a left crankcase member 10a and a right crankcase member 10b by a vertical division surface (mating surface) 34 positioned in a substantially center of a lateral crankcase width. The lateral crankcase width means the width of the crankcase 10 in the vehicle width direction, and the vertical division surface 34 including a cylinder bore center (not shown) of the engine. A clutch chamber wall 36 is integrally formed to a right end of the right crankcase member 10b, and constitutes a partial wall (a left wall portion) of a peripheral wall surrounding a clutch chamber 35. A clutch case 39 is fixed to a right end face of the clutch chamber wall 36 by bolts 40 or the like. A clutch cover 41 is fixed to a right end face of the clutch case 39. A multi disc friction clutch 42 is housed in the clutch chamber 35 and mounted on a right end of the input shaft 26. The clutch chamber wall 36, the clutch case 39 and the clutch cover 41 are protruded upward from the top wall of the crankcase 10.
[The Configuration of the Starting Gear Case and the Starting Gear Train]
In FIG. 4, a first motor mounting portion 46 is integrally formed to a left end of the left crankcase member 10a and protrudes upward from the top wall of the left crankcase member 10a. The first motor mounting portion 46 serves as a right wall of a starting gear chamber 48. A starting gear chamber cover 47 integrally formed with the generator cover 16 is fixed to a left end face of the first motor mounting portion 46. The starting gear chamber cover 47 and the first motor mounting portion 46 surround the starting gear chamber 48. A circular window hole 50 for gear assembling and inspection is formed in the starting gear chamber cover 47. A circular lid 52 is removably fitted to the window hole 50.
A circular motor mounting hole 55 is formed in the first motor mounting portion 46, and has a hole centerline O6 in parallel with the axis O1 of the crankshaft 20. The starting motor 18 has a cylindrical end 57 on an output gear 56 side thereof. The cylindrical end 57 is fitted in the motor mounting hole 55 via an O-ring 58. The output gear 56 is protruded into the starting gear chamber 48 in parallel with the crankshaft 20.
The starting gear train includes the output gear 56 of the starting motor 18, first and second starting idle shafts 61, 62, a first starting idle gear 63 with a large diameter and a second starting idle gear 64 with a small diameter provided on the first starting idle shaft 61, a third starting idle gear 65 integrally formed with the second starting idle shaft 62, and a starting gear 66 fitted onto the crankshaft 20.
The first starting idle shaft 61 is straddle-supported by a support recess portion 71 formed in the first motor mounting portion 46 and a support recess portion 72 formed in the circular lid 52. The first starting idle gear 63 is engaged with the output gear 56 of the starting motor 18 and is coupled to the first starting idle shaft 61 via a torque limiter 74. The second starting idle gear 64 rigidly is fixed (e.g., screwed) to the first starting idle shaft 61. The second starting idle shaft 62 is straddle-supported by a support recess portion 75 formed in the left end face of the left crankcase member 10a and a support recess portion 76 formed in the starting gear chamber cover 47. The third starting idle gear 65 is engaged with the second starting idle gear 64 and the starting gear 66. The starting gear 66 is coupled to a rotor 77 of the generator 17 via a one-way clutch 67. The rotor 77 is fixed to the crankshaft 20. Rotating power of the starting motor 18 for starting is transmitted to the crankshaft 20 via the output gear 56, the first starting idle gear 63, the torque limiter 74, the first starting idle shaft 61, the second starting idle gear 64, the third starting idle gear 65, the starting gear 66, the one-way clutch 67 and the rotor 77 in the starting gear chamber 48.
[The Mounting Configuration of the Starting Motor]
FIG. 2 clearly shows an arrangement of the shafts and gears of the starting gear train. In FIG. 2, the starting motor 18 is arranged in such a manner that an axis (motor axis) O5 of the output gear 56 is positioned substantially just above the axis O3 of the input shaft 26 of the transmission 22. The first starting idle shaft 61 is arranged forwardly and downwardly of the output gear 56. The second starting idle shaft 62 is arranged forwardly and downwardly of the first starting idle shaft 61 and is arranged slightly rearwardly and upwardly from the upper end of the starting gear 66.
In FIG. 3, the first motor mounting portion 46 is formed to be protruded substantially rearward and upward from a front end of the top wall of the gear transmission chamber 23 of the crankcase 10.
FIG. 6 is an enlarged view near the starting motor 18 of FIG. 5, and FIG. 7 is a left side view of FIG. 6. In FIG. 6, as described above, the cylindrical end 57 of the starting motor 18 on the output gear 56 side (left) is fitted in the motor mounting hole 55 of the first motor mounting portion 46 via the O ring 58, and the first mounting portion 46 is integrally formed with the left crankcase member 10a. A boss 80 is integrally formed with the starting motor 18 on rightward lower end thereof. The boss 80 is placed on the upper surface of a second motor mounting portion 81 formed on the top wall of the right crankcase member 10b and is fixed to the upper surface of the second motor mounting portion 81 by a bolt 83 inserted from above.
As shown in FIG. 6, the starting motor 18 is arranged above the top wall of the crankcase 10 and is arranged between the first motor mounting portion 46 on the left side of the starting motor 18 and the clutch chamber wall 36 on the right side of the starting motor 18. As shown in FIG. 7, as seen in the crankshaft axial direction, the first motor mounting portion 46, the starting motor 18 and an upward protruded portion of the clutch chamber wall 36 are arranged so as to overlap with each other.
In FIG. 6, a recess portion 85 recessed rightward is formed on the clutch chamber wall 36. The recess portion 85 is extended from the top wall of the crankcase 10 to the upper end of the clutch chamber wall 36. Such recess portion 85 is formed to secure an operating space D1 used for mounting the starting motor 18 in the region rightwardly of a right end P1 of the boss 80 of the starting motor 18. The operating space D1 is set to be larger than an insertion stroke (fitted width) S1 of the cylindrical end 57 of the starting motor 18 into the motor mounting hole 55.
[The Mounting Operation of The Starting Motor and The Starting Gear Train]
(1) In FIG. 6, the starting motor 18 is displaced to the right from the final mounted position shown in FIG. 6 by about the insertion stroke S1, and then, inserted from above between the dutch chamber wall 36 and the first motor mounting portion 46. At this time, the boss 80 is inserted into the operating space D1. After insertion of the staring motor 18, the starting motor 18 is moved leftward to the final mounted position shown in FIG. 6, thereby fitting the cylindrical end 57 in the motor mounting hole 55. The bolt 83 is inserted into the boss 80 from above, thereby fastening the boss 80 to the upper surface of the second motor mounting portion 81. In FIG. 7, in a state that the starting motor 18 is mounted at final mounted position, the starting motor 18 is positioned below the chain tensioner 15.
(2) In FIG. 4, the first and second starting idle shafts 61, 62 are mounted on the left crankcase member 10a. The starting gear chamber cover 47 from which the circular lid 52 is removed is attached, together with the generator cover 16, to the first motor mounting portion 46 and the left end face of the left crankcase member 10a. Then, the circular lid 52 is fastened to the window hole 50.
Effects of the Embodiment
(1) As shown in FIG. 3, since the input shaft 26 and the reverse idle shaft 31 are arranged on the upper and lower side positions of the reference line M connecting the axis O1 of the crankshaft 20 and the axis O2 of the output shaft 28, and the starting motor 18 is arranged in such a manner that the motor axis O5 is substantially just above the input shaft 26, the size of the crankcase 10 in the forward and rearward direction can become shorter, and the width of the engine in the forward and rear ward direction can become smaller.
(2) As shown in FIG. 4, since the left crankcase member 10a is integrally formed with the first motor mounting portion 46 having the motor mounting hole 55, the mounted position of the starting motor 18 is not greatly displaced leftward, therefore the starting gear chamber 48 is not greatly protruded leftward from the crankcase 10. Consequently, the lateral width of the engine can become smaller.
(3) As shown in FIG. 5, since the crankcase 10 is divided into the left and right crankcase members 10a, 10b and the left crankcase member 10a is integrally formed with the first motor mounting portion 46 having the motor mounting hole 55, when the left crankcase member 10a is machined, the motor mounting hole 55 can be machined at the same time, together with machining of holes supporting the input shaft 26, the output shaft 28, the change drum 32, the crankshaft 20 (FIG. 4), and etc. Consequently, the motor mounting hole 55 can be machined easily at high accuracy.
(4) As shown in FIG. 5, since the starting motor 18 arranged above the top wall of the crankcase 10 is arranged between the clutch chamber wall 36 protruded upward from the top wall of the crankcase 10 and the first motor mounting portion 46 protruded upward from the top wall of the crankcase 10, and the configuration of the starting motor 18, the clutch chamber wall 36 and the first motor mounting portion 46 are overlapped with each other in the crank shaft axial direction, the shape of the engine, as seen in the crankshaft direction, can become smaller.
(5) As shown in FIG. 6, since the mounting operating space D1 having a fixed size is secured rightward of the right end P1 of the starting motor 18, the starting motor 18 can be fitted in the motor mounting hole 55 without interfering with the clutch chamber wall 36 even if the engine E is a single cylinder engine. Namely, the mounting operation of the starting motor 18 becomes easy.
(6) In FIG. 4, since the two starting idle shafts 61, 62 are arranged in the starting gear train, when a predetermined reduction gear ratio of the starting gear train is obtained, the diameters of the second starting idle gear 64 and the third starting idle gear 65 can become smaller, as compared with a starting gear train having one starting idle shaft. Therefore, the degree of freedom of the layout of the starting idle gears 63, 64, 65 can be increased, as seen in the crankshaft axial direction, the shape of the starting gear train can become smaller.
Other Embodiments
(1) In the above embodiment, the starting gear chamber cover 47 is integrally formed with the generator cover 16. However, in the present invention, the starting gear chamber cover 47 can be formed separately from the generator cover 16.
(2) In the above embodiment, the two starting idle shafts are arranged in the starting gear train. However, in the present invention, three or more starting idle shafts can be arranged in the starting gear train.
(3) The present invention is not limited to the above-described preferred embodiments, and therefore, encompasses various modifications within the scope without departing from the spirit of the invention as defined in the appended claims.
The present invention is not limited to the engine for saddle-type four wheeled vehicle and is applicable to an engine for a vehicle, such as a motorcycle or a three wheeled vehicle.
Patent Application
20080072861
