KR20020055378A - Engine for Backbone-type Motorcycle - Google Patents

Abstract

PURPOSE: To decrease bending as small as possible in an intake air system to attain reduction of intake air resistance, by enlarging a space between a cylinder head and a back bone, in a motorcycle of back bone type. CONSTITUTION: In this motorcycle, an engine main unit 20 of an engine E suspended in a back bone 2 inclined rearward in a downward direction from a head pipe 1 is constituted of a crank case 21 supporting a crankshaft 28, a cylinder block 22 arranged so as to tilt an axial line Ab of a cylinder bore 22a with a small gradient α forward in an upward direction, and a cylinder head 23 connected to a front end of this cylinder block, to arrange an intake air system 70 in a space 66 between these cylinder head 23 and back bone 2, the cylinder block 22 is arranged so as to offset the axial line Ab of the cylinder bore 22a by a distance S downward from an axial line Ac of the crankshaft 28.

Description

Engine for backbone motorcycle {Engine for Backbone-type Motorcycle}

The present invention projects the engine main body of the engine over the backbone inclined rearward downward from the head pipe of the vehicle body frame, the crankcase supporting the crankshaft and the front of the crankcase, and the axis of the cylinder bore forward upward. The present invention relates to a backbone type two-wheeled vehicle comprising a cylinder block arranged to be inclined and a cylinder head joined to a front end of the cylinder block, and having an intake system of an engine disposed in a space between the cylinder head and the backbone. It is about improvement of the engine of a motorcycle.

Such motorcycles are already known, for example, as disclosed in Japanese Patent Laid-Open No. 2000-249028.

In such a two-wheeled vehicle, the backbone inclined rearward downward from the head pipe of the body frame has the advantage of facilitating the ascending and descending of the operator by avoiding interference with the operator's foot, and the cylinder block projecting forward from the crankcase. Of the cylinder bore so that the axis of the cylinder bore is tilted forward and upward, the natural inlet to the crankcase side of the lubricated oil of the operation valve mechanism in the cylinder head is promoted, This is to free up space for installation.

By the way, in such a motorcycle, the output of an engine and low fuel economy must be improved, and the space | interval between a cylinder head and a backbone is calculated | required in order to reduce the intake resistance by making the bending of an intake machine as small as possible.

An object of the present invention is to provide an engine of the backbone type motorcycle which can satisfy the above requirements without changing the forward upward angle of the axis of the cylinder bore.

1 is a side view of a backbone type motorcycle showing a first embodiment of the present invention;

FIG. 2 is an enlarged vertical plan view of the engine along line 2-2 of FIG. 1;

3 is a cross-sectional view taken along line 3-3 of FIG. 2;

4 is a cross-sectional view taken along line 4-4 of FIG. 2;

5 is a cross-sectional view corresponding to FIG. 3 showing a second embodiment of the present invention.

<Explanation of symbols for main parts of drawing>

E… Engine F… Body frame

M… A motorcycle

S… Down offset amount from crankshaft axis of cylinder bore axis

S ′…. Offset amount downward from cylinder bore axis of cam axis axis

One … Head pipe 2... Backbone

20... Engine body 21. Crankcase

22. Cylinder block 23. Cylinder head

24. Hanger boss (all hanger bosses) 28. Crankshaft

38. Camshaft 66. space

70... Intake machine 80... Starting motor

85... Transmission 86. Input shaft

87. Output shaft

In order to achieve the above object, the present invention provides a crankcase for supporting a crankshaft, an engine body of an engine that spans a backbone inclined rearward downward from a head pipe of a vehicle body frame, and protrudes forward from this crankcase, and includes a cylinder Backbone type two-wheeled vehicle which consists of the cylinder block arrange | positioned so that the axis of a bore may incline forward upward, and the cylinder head joined to the front end of this cylinder block, and arrange | positions the engine intake machine in the space between the cylinder head and the said backbone. In the first aspect, the cylinder block is arranged such that the axis of the cylinder bore is offset downward with respect to the axis of the crankshaft.

According to this first feature, the cylinder block and the cylinder head are displaced downward with respect to the crankcase while maintaining the inclined state of the axis of the cylinder bore, so that the space between the cylinder head and the backbone can be enlarged, and thus the space It is possible to reduce the intake resistance arranged in the air inlet to reduce the intake resistance, thereby improving the engine output performance and low fuel efficiency.

The offset of the cylinder bore's axis to the crankshaft's axis causes a reduction in side thrust acting on the piston at maximum pressure in the engine's expansion process, thereby reducing the slide frictional resistance of the piston and further reducing fuel efficiency. Can be improved.

In addition to the first aspect, the present invention is characterized in that the cylinder head is disposed so that the axis of the cam valve for the operation valve supported by the cylinder head is offset downward with respect to the axis of the cylinder bore.

According to this second feature, the cylinder head is displaced in two stages downward with respect to the crankcase, so that the space between the cylinder head and the backbone can be further enlarged, and the intake of the intake machine disposed in the space is reduced, which leads to intake It is possible to effectively reduce the resistance.

In addition to the first or second aspect of the present invention, a starter motor is attached to the upper part of the crankcase at the front side of the crankshaft, and immediately after the starter motor and on the upper surface of the crankcase immediately above the crankshaft. The 3rd characteristic is that this hanger boss was formed.

According to this third feature, the starting motor can be installed on the crankcase while using a relatively large space between the crankcase and the backbone. In addition, the hanger boss is disposed near the center of gravity of the engine, so that the vibration of the engine is less affected, and thus the vibration transmission from the hanger boss to the backbone is also reduced, thereby contributing to improved ride comfort.

In addition to the third aspect of the present invention, the input shaft and the output shaft of the transmission mounted to the crankcase are arranged in parallel with the crank shaft, and the input shaft is disposed above the crank shaft and the output shaft. 4 features.

According to this fourth feature, the distance between the crankshaft and the output shaft is shortened, whereby the crankcase can be made compact, and further, the engine can be made compact. In addition, since the hanger boss occupies a position just above the crankshaft, it is necessary to swell a portion of the upper wall of the crankcase immediately above the input shaft, depending on the upward offset of the crankshaft and the output shaft of the input shaft. Even if there is, the interference between the bulge and the hanger boss can be avoided.

An embodiment of the present invention will be described based on an embodiment of the present invention shown in the accompanying drawings.

1 to 4 show a first embodiment of the present invention, FIG. 1 is a side view of a backbone type motorcycle, FIG. 2 is a longitudinal enlarged plan view of the engine along line 2-2 of FIG. 1, and FIG. 3 is FIG. 2. 4 is a cross-sectional view taken along line 3-3, and FIG. 4 is a cross-sectional view taken along line 4-4 of FIG.

In addition, in the following description, front, rear, left and right are saying based on the motorcycle M which applies this invention.

First, the description begins with the description of the first embodiment of the present invention shown in Figs. 1 and 3, the body frame F of the motorcycle M is a head pipe 1, a steel pipe backbone 2 which is welded to the head pipe 1 and inclined downward downward, and It consists of the rear frame 3 of the steel pipe welded to the rear end of this backbone 2. As shown in FIG. The head pipe 1 is pivotally supported so that all the forks 5 which support the front wheels 4f are steerable.

A center bracket 7 extending downward is welded to the rear end of the rear frame 3, and the rear fork 6 pivotally supporting the rear wheels 4r is pivotally supported through the pivot shaft 8. The rear cushion 9 is connected between the rear fork 6 and the rear frame 3. Moreover, the storage box 10 which accommodates a helmet etc., and the fuel tank 11 are attached back and forth to the upper surface of the rear frame 3, and the seat 12 is installed so that opening and closing is possible in the upper part.

A short cylinder engine E hangs on the backbone 2. The engine E is covered by the body cover 13 together with the backbone 2, and a pair of leg shields 23 and 23 protruding left and right outwards are connected to the front end of the body cover 13. do.

2 to 4, in the short-term cylinder engine E, the engine main body 20 is coupled to the crankcase 21 and the crankcase 21, and the cylinder block 22 protruding forward. And the cylinder head 23 joined to the front end of the cylinder block 22. The crankcase 21 is formed with one upper hanger boss 24 on its upper surface and one pair of rear hanger bosses 25 and 25 on its rear surface, and the upper hanger boss 24 includes a backbone 2. The rear hanger bosses 25 and 25 are fixed to the center bracket 7 by bolts 26, respectively, to all brackets 15 protruding downwardly in the middle of the brackets.

The crankcase 21 is composed of a left case half 21a and a right case half 21b which are divided left and right on a vertical surface P including the axis of the backbone 2, and both case half 21a. , The crankshaft 28 arranged in the horizontal direction by 21b is supported through the left and right pair of bearings 27 and 27 '. The crankshaft 28 is connected to the piston 29 which slides in the single cylinder bore 22a which the cylinder block 22 has through the connecting rod 30. As shown in FIG.

The cylinder block 22 is arrange | positioned so that the axis line Ab of the cylinder bore 22a may be located on the said perpendicular | vertical surface P, and also inclined by the small gradient (alpha) of forward upward.

The cylinder head 23 has a combustion chamber 31 in which the top surface of the piston 29 faces, an intake port 32 connected to the combustion chamber 31 and opened on the upper surface of the cylinder head 23, and the same combustion chamber ( An exhaust port 33 which is connected to 31 and opens on the lower surface of the cylinder head 23 is formed, and at the same time, the intake and exhaust valves 34 and 35 which open and close these intake and exhaust ports 32 and 330 are mounted. Then, an operation valve mechanism 36 for opening and closing the intake and exhaust valves 34 and 35 is provided in the operation valve chamber 37 of the cylinder head 23.

The operating valve mechanism 36 is supported by the pair of left and right bearings 39, 39 ′ on the cylinder head 23 in parallel with the crankshaft 28 at the middle of the intake and exhaust valves 34, 35. A cam shaft 38, an intake rocker arm 40 axially supported by the cylinder head 23 so as to interlock between the cam shaft 38 and the intake valve 34, the cam shaft 38 and the exhaust valve ( It consists of an exhaust rocker arm 41 axially supported by the cylinder head 23 so as to interlock between 35, and valve springs 42 and 43 for pressing the intake and exhaust valves 34 and 35 in the closing direction, respectively.

The camshaft 38 is connected to the crankshaft 28 via the time-controlled transmission 61. The time-controlled transmission 61 has a drive sprocket 62 fixed to the crankshaft 28 adjacent to the outer side of the bearing 27 on the left side supporting the crankshaft 28 and one end of the camshaft 38. It consists of a driven sprocket 63 fixed to the endless endless timing chain 64 wound around both sprockets 62 and 63, and the rotation of the crankshaft 28 has a reduction ratio of 1/2. To the camshaft 38. The timing chain 64 is accommodated in the timing chain passage 65 formed in one side wall of the cylinder block 22.

The cylinder block 22 is arranged to offset the axis Ab of the cylinder bore 22a downwards by a distance S with respect to the axis Ac of the crankshaft 28, and the cylinder head 23 is a cam shaft ( The axis Am of 38 is arranged to be offset by the distance S 'below the axis Ab of the cylinder bore 22a. By this two-stage offset, the cylinder head 23 is displaced two steps downward with respect to the crankcase 21 while maintaining the inclined state of the cylinder bore 22a, so that the cylinder head 23 and the backbone ( The space 66 between 2) can be enlarged effectively.

1 and 3, the intake machine 70 of the engine E is disposed in the space 66. The intake pipe 71 constituting a part of the intake machine 70 is coupled to the upper surface of the cylinder head 23 so as to communicate with the intake port 32. This intake pipe 71 is erected upward from the cylinder head 23 and is bent forward along the lower surface of the backbone 2, and a side draft vaporizer 72 is connected to its end, i.e., the upstream end thereof. The air cleaner 73 is connected to the intake port of. In this way, the intake machine 70 is configured.

And since the space 66 between the cylinder head 23 and the backbone 2 which arrange | position this intake machine 70 expands as mentioned above, it is possible to set the curvature radius of the bending part of the intake pipe 71 large. As a result, the intake resistance in the intake pipe 71 is reduced, so that the output of the engine can be improved, and further, the low fuel consumption can be improved.

In addition, since the axis Ab of the cylinder bore 22a is inclined with the small gradient α of the front upward as before, the timing chain passage 65 is also inclined in the same manner. Therefore, the oil supplied to the operation valve mechanism 36 of the cylinder head 23 by the oil pump not shown from the bottom oil storage part of the cramp case 21 naturally follows the timing chain passage 65 after lubrication. It may flow down and return to the oil reservoir.

Moreover, according to the offset with respect to the axis line Ac of the crankshaft 28 of the axis line Ab of the cylinder bore 22a, the side which acts on the piston 29 at the maximum pressure in the expansion process of the engine E. As the thrust is reduced, the slide frictional resistance of the piston 29 can be reduced to further improve low fuel efficiency.

An exhaust pipe 81 communicating with the exhaust port 33 is coupled to the lower surface of the cylinder head 23, and the exhaust pipe 81 is bent backward and continues, and a muffler is disposed on one side of the rear wheel 4r (not shown). ) Is connected.

2 and 3, one end of the crankshaft 28 is key-coupled with a rotor 76 of the generator 75, and a starter gear rotatably supported by the rotor 76 and the crankshaft 28 ( 77 is connected via a one-way clutch 78. The one-way clutch 78 is capable of transmitting rotational force in only one direction from the starting gear 77 to the rotor 76, and also starts the motor 80 for driving the starting gear 77 through the reduction gear train 79. Is attached to the top of the crankcase 21 on the front side of the crankshaft 28. And all the hanger bosses 24 for engine hanging are arrange | positioned just behind this starter motor 80, and just above the crankshaft 28. As shown in FIG.

In this way, the starting motor 80 can be installed on the crankcase 21 while using a relatively large space 66 between the crankcase 21 and the backbone 2. In addition, the upper hanger boss 24 is arranged near the center of gravity of the engine E, so that it is less affected by the vibration of the engine E, and thus, from the upper hanger boss 24 to the backbone 2. Vibration transmission also decreases, contributing to the improvement of ride comfort.

2 and 3, the crankcase 21 is accommodated with a transmission 85 having an input shaft 86 and an output shaft 87 arranged in parallel with the crank shaft 28. At that time, the input and output shafts 86 and 87 are supported by the crankcase 21 via a pair of left and right bearings 94 and 94 ', 95 and 95', respectively. A plurality of stages of transmission gear trains 88 ₁ to 88 _n are configured between these input and output shafts 86 and 87. The generated power of the crankshaft 28 is transmitted to the input shaft 86 via the centrifugal clutch 89, the primary reduction gear train 90 and the transmission clutch 91, and 1 selected from the input shaft 86. It is transmitted to the output shaft 87 via two shift gear trains, and is also transmitted to the rear wheel 4r via the chain transmission 92 disposed outside the clutch case 21 to drive it.

In the transmission 85, the output shaft 87 is disposed on substantially the same horizontal plane as the crank shaft 28, and the input shaft 86 is offset above these crank shaft 28 and the output shaft 87. It is disposed at an intermediate position between the two axes 28, 87. Further, above the input shaft 86, a shift drum 93 for selecting the shift gear trains 88 ₁ to 88 _n is disposed.

In this way, the distance between the crankshaft 28 and the output shaft 87 can be shortened, and the crankcase 21 can be made compact, and further, the engine E can be made compact. In addition, since all of the hanger bosses 24 occupy a position approximately above the crankshaft 28, the input according to the upward offset with respect to the crankshaft 28 and the output shaft 87 of the input shaft 86. Even when it is necessary to swell a part of the upper wall of the crankcase 21 directly above the shaft 86, the interference between the bulging portion and the hanger bosses 24 can be avoided.

Next, a second embodiment of the present invention shown in FIG. 5 will be described.

In this second embodiment, the water jacket 96 is formed in the cylinder block 22 and the cylinder head 23 of the engine E. Only the axis Ab of the cylinder bore 22a of this cylinder block 22 is offset downward by the distance S with respect to the axis Ac of the crankshaft 28. That is, the axis Am of the cam shaft 38 is arrange | positioned on the axis Ab of the cylinder bore 22a. The upper hanger boss 24 is integrally formed with the upper wall of the cylinder block 22. In the intake system 70, a throttle body 172 is provided in place of the vaporizer 72 of the previous embodiment, whereby the intake pipe 71 can inject fuel toward the outlet of the intake port 32. The fuel injection valve 74 is attached.

The input shaft 86 and the output shaft 87 of the transmission 85 are disposed on substantially the same horizontal plane as the crank shaft 28.

Other configurations are substantially the same as those in the previous embodiment, and therefore, corresponding parts to those in the previous embodiment will be denoted by the same reference numerals, and description thereof will be omitted.

This invention is not limited to the said Example, A various design change is possible in the range which does not deviate from the summary.

As described above, according to the first aspect of the present invention, the engine main body of the engine, which spans the backbone inclined rearward downward from the head pipe of the body frame, protrudes forward from the crankcase supporting the crankshaft, and the crankcase forward. And a cylinder block which is arranged such that the axis of the cylinder bore is inclined forward and upward, and a cylinder head joined to the front end of the cylinder block, and a backbone type in which an engine intake machine is arranged in a space between the cylinder head and the backbone. In the motorcycle, since the cylinder block is arranged so that the axis of the cylinder bore is offset downward with respect to the axis of the crankshaft, the cylinder block and the cylinder head are displaced downward with respect to the crankcase while maintaining the inclined state of the axis of the cylinder bore. The space between the cylinder head and the backbone Therefore, the bending of the intake machine disposed in the space can be reduced, thereby reducing the intake resistance, thereby improving the engine output performance and low fuel efficiency. The offset of the cylinder bore's axis to the crankshaft's axis causes a reduction in side thrust acting on the piston at maximum pressure in the engine's expansion process, thereby reducing the slide frictional resistance of the piston and further reducing fuel efficiency. Can be improved.

According to the second aspect of the present invention, in addition to the first aspect, the cylinder head is disposed so that the axis of the cam valve for the operation valve supported by the cylinder head is offset downward with respect to the axis of the cylinder bore. The displacement between the cylinder head and the backbone can be further expanded in two stages, so that the bend of the intake machine disposed in the space can be reduced, so that the intake resistance can be effectively reduced.

Further, according to the third aspect of the present invention, in addition to the first or second aspect, a starter motor is attached to an upper portion of the crankcase at the front side of the crankshaft, immediately after the starter motor, and crank just above the crank shaft. Since the hanger boss in which the said backbone hangs was formed in the upper surface of a case, it becomes possible to install a starting motor on a crankcase using the comparatively large space between a crankcase and a backbone. In addition, the hanger boss is disposed near the center of gravity of the engine, so that the vibration of the engine is less affected, and thus the vibration transmission from the hanger boss to the backbone is also reduced, thereby contributing to improved ride comfort.

According to a fourth aspect of the present invention, in addition to the third aspect, the input shaft and the output shaft of the transmission mounted to the crankcase are arranged in parallel with the crank shaft, respectively, and the input shaft is above the crank shaft and the output shaft. Since it is arrange | positioned at the position, the distance between a crankshaft and an output shaft is shortened and a crankcase can be made compact and furthermore, an engine can be made compact. In addition, since the hanger boss occupies a position just above the crankshaft, it is necessary to swell a portion of the upper wall of the crankcase immediately above the input shaft, depending on the upward offset of the crankshaft and the output shaft of the input shaft. Even if there is, the interference between the bulge and the hanger boss can be avoided.

Claims (4)

Crank case 21 supporting the crankshaft 28 with the engine main body 20 of the engine E which spans the backbone 2 inclined rearward downward from the head pipe 1 of the vehicle body frame F. And a cylinder block 22 which protrudes forward from the crankcase 21 and is arranged such that the axis Aa of the cylinder bore 22a is inclined forward and upward, and joined to the front end of the cylinder block 22. In the backbone type motorcycle which comprises the cylinder head 23, and arrange | positioned the intake machine 70 of the engine E in the space 66 between the cylinder head 23 and the said backbone, An engine of a backbone type motorcycle, characterized in that the cylinder block (22) is arranged such that the axis (Ab) of the cylinder bore (22a) is offset (S) downward with respect to the axis (Ac) of the crankshaft (28). The method of claim 1, The cylinder head 23 is arrange | positioned so that the axis line Am of the cam shaft for operation valves supported by the cylinder head 23 may offset S 'below the axis line Ab of the cylinder bore 22a, It is characterized by the above-mentioned. The engine of the backbone motorcycle. The method according to claim 1 or 2, The starter motor 80 is attached to the upper part of the crankcase 21 on the front side of the crankshaft 28, and immediately after the starter motor 80, and just above the crankshaft 28, the crankcase 21 is mounted. An engine of a backbone type motorcycle, characterized in that a hanger boss (24) is formed on the upper surface of the hanger boss (24). The method of claim 3, The input shaft 86 and the output shaft 87 of the transmission 85 mounted on the crankcase 21 are arranged in parallel with the crank shaft 28, respectively, and the input shaft 86 is placed on the crank shaft 28. And an output shaft (87) above the backbone type motorcycle.