JP2002201955A - Backbone type motorcycle engine - Google Patents

Abstract

(57) [Summary] [PROBLEMS] In a backbone type motorcycle, the space between a cylinder head and a backbone is enlarged to minimize the bending of the intake system and reduce intake resistance. A crankcase (2) for supporting an engine body (20) of an engine (E) suspended from a back pipe (2) inclined backward and downward from a head pipe (1).
1 and a cylinder block 2 arranged such that the axis Ab of the cylinder bore 22a is inclined with a small gradient α upward and forward.
2 and a cylinder head 23 joined to the front end thereof, and in a motorcycle in which an intake system 70 is disposed in a space 66 between the cylinder head 23 and the backbone 2, the axis Ab of the cylinder bore 22a has a crankshaft. 28
The cylinder block 22 is arranged so as to be offset S downward from the axis Ac.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a vehicle body frame,
The engine body of the engine suspended from the back pipe that extends downward and downward from the head pipe is mounted on the crankcase that supports the crankshaft and protrudes forward from the crankcase so that the axis of the cylinder bore is inclined forward and upward. The present invention relates to a backbone type motorcycle comprising a cylinder block to be disposed and a cylinder head joined to a front end of the cylinder block, wherein an intake system of an engine is disposed in a space between the cylinder head and the backbone. The present invention relates to improvement of a motorcycle engine.

[0002]

2. Description of the Related Art Such a motorcycle is disclosed in, for example,
It is already known as disclosed in Japanese Patent Publication No. 0-249028.

[0003]

In such a motorcycle, a backbone of the body frame, which is inclined downward and backward from the head pipe, is provided so that the backbone of the body frame can be easily interfered with the foot of the driver to easily get on and off the driver. Arranging the cylinder block projecting forward from the crankcase so that the axis of the cylinder bore is inclined forward and upward, the oil crank that has finished lubricating the valve train in the cylinder head. This is to secure the installation space of the intake system between the cylinder head and the backbone while promoting natural flow to the case side.

[0004] By the way, in such a motorcycle,
In order to improve engine output and fuel economy, the space between the cylinder head and the backbone must be increased in order to minimize the bending of the intake system and reduce intake resistance.

[0005] It is an object of the present invention to provide an engine of the backbone type motorcycle which can satisfy the above-mentioned requirement without changing the forward upward angle of the axis of the cylinder bore.

[0006]

In order to achieve the above object, the present invention provides an engine body of an engine suspended from a backbone of a vehicle body frame, which is inclined backward and downward from a head pipe. It comprises a crankcase to be supported, a cylinder block projecting forward from the crankcase and arranged so 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. In a backbone type motorcycle in which an intake system of an engine is arranged in a space between a head and the backbone,
A first feature is that the cylinder block is arranged so that the axis of the cylinder bore is offset downward with respect to the axis of the crankshaft.

According to the 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, and the space between the cylinder head and the backbone is enlarged. Therefore, the bending of the intake system provided in the space can be reduced to reduce the intake resistance, and the output performance and fuel economy of the engine can be improved.

Further, the offset of the axis of the cylinder bore with respect to the axis of the crankshaft causes a decrease in the side thrust acting on the piston at the maximum pressure in the expansion process of the engine, thereby reducing the sliding friction resistance of the piston and improving fuel economy. Further improvement can be achieved.

According to the present invention, in addition to the first feature, the cylinder head is arranged so that the axis of the valve operating cam shaft supported by the cylinder head is offset downward with respect to the axis of the cylinder bore. This is the second feature.

According to the second feature, the cylinder head is displaced two steps downward with respect to the crankcase, so that the space between the cylinder head and the backbone can be further expanded, and the cylinder head is disposed in the space. Thus, it is possible to effectively reduce the intake air system and reduce the intake resistance.

According to the present invention, in addition to the first or second feature, a starting motor is mounted on an upper part of a crankcase in front of the crankshaft, and an upper surface of the crankcase is provided immediately after the starting motor and almost immediately above the crankshaft. A third feature is that a hanger boss suspended from the backbone is formed.

According to the third feature, the starting motor is
It can be installed on the crankcase while utilizing a relatively large space between the crankcase and the backbone. Moreover, the hanger boss is arranged at a position close to the center of gravity of the engine, so that it is less affected by the vibration of the engine. Therefore, the transmission of the vibration from the hanger boss to the backbone is also reduced, contributing to an improvement in riding comfort. I can do it.

Further, in addition to the third feature, the present invention provides an input shaft and an output shaft of a transmission incorporated in a crankcase, each of which is arranged parallel to the crankshaft, and the input shaft is connected to the crankshaft and the output shaft. The fourth feature is that the device is disposed at a higher position than the above.

According to the fourth feature, the distance between the crankshaft and the output shaft is reduced, and the compactness of the crankcase and the compactness of the engine can be achieved. In addition, since the hanger boss occupies a position almost directly above the crankshaft, a part of the upper wall of the crankcase immediately above the input shaft bulges upward due to the upward offset of the input shaft from the crankshaft and the output shaft. Even if necessary, interference between the bulging portion and the hanger boss can be avoided.

[0015]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described based on one 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, and FIG.
FIG. 3 is an enlarged vertical sectional view of the engine taken along line 2-2 of FIG. 1, FIG. 3 is a sectional view taken along line 3-3 of FIG. 2, FIG. 4 is a sectional view taken along line 4-4 of FIG. FIG. 6 is a sectional view corresponding to FIG. 3 and showing a second embodiment of the present invention.

In the following description, the terms front and rear, left and right refer to the motorcycle M to which the present invention is applied.

First, a description will be given of the first embodiment of the present invention shown in FIGS. 1 and 3, a body frame F of a motorcycle M includes a head pipe 1, a steel pipe backbone 2 that is welded to the head pipe 1 and extends rearward and inclined downward and downward, and a rear end of the backbone 2. And a rear frame 3 made of steel pipe to be welded.
A front fork 5 for pivotally supporting the front wheel 4f is pivotably supported on the head pipe 1 so as to be steerable.

A center bracket 7 extending downward is welded to the rear end of the rear frame 3, and a rear wheel 4
The rear fork 6 that supports r is pivotally supported via a pivot shaft 8. A rear cushion 9 is connected between the rear fork 6 and the rear frame 3. A storage box 10 for housing a helmet and the like and a fuel tank 11 are mounted on the upper surface of the rear frame 3 in front of and behind, and a seat 12 is installed on the upper part thereof so as to be openable and closable.

A single cylinder engine E is suspended from the backbone 2. The engine E is covered by a body cover 13 together with the backbone 2, and a pair of leg shields 23, 23 projecting right and left outward are connected to a front end of the body cover 13.

As shown in FIGS. 2 to 4, in the single-cylinder engine E, the engine body 20 includes a crankcase 21, a cylinder block 22 connected to the crankcase 21 and protruding forward, and a cylinder block 22. And a cylinder head 23 joined to a front end of the cylinder head 22. The crankcase 21 has one upper hanger boss 24 on its upper surface and a pair of upper and lower rear hanger bosses 2 on its rear surface.
5 and 25 are integrally formed, and the upper hanger boss 24 is formed.
The rear hanger bosses 25 are fixed to the center bracket 7 by bolts 26, respectively.

The crankcase 21 is composed of a left case half 21a and a right case half 21b which are divided right and left by a vertical plane P including the axis of the backbone 2. A pair of left and right bearings 27, 2
Supported via 7 '. The crankshaft 28 has a single cylinder bore 22a of the cylinder block 22.
A piston 29 sliding inside is connected via a connecting rod 30.

The cylinder block 22 is arranged such that the axis Ab of the cylinder bore 22a is located on the vertical plane P and is inclined at a small forward inclination α.

The cylinder head 23 has a combustion chamber 31 facing the top surface of a piston 29, an intake port 32 connected to the combustion chamber 31 and opening to the upper surface of the cylinder head 23, and a cylinder head 23 connected to the combustion chamber 31 and connected to the combustion chamber 31. An exhaust port 33 is formed on the lower surface, and the intake and exhaust valves 3 for opening and closing the intake and exhaust ports 32, 33 are formed.
4, 35 are attached. And intake and exhaust valves 34,3
A valve mechanism 36 for opening and closing the valve 5 is installed in a valve chamber 37 of the cylinder head 23.

The valve operating mechanism 36 is provided with the intake and exhaust valves 3
In order to interlock the camshaft 38 which is parallel to the crankshaft 28 and supported on the cylinder head 23 via a pair of left and right bearings 39, 39 'at an intermediate portion between the camshaft 38 and the intake valve 34. The intake rocker arm 40 pivotally supported by the cylinder head 23, the exhaust rocker arm 41 pivotally supported by the cylinder head 23 for interlocking the camshaft 38 and the exhaust valve 35, and the intake and exhaust valves 34, 35 in the closing direction. It is composed of biasing valve springs 42 and 43.

The camshaft 38 is connected to the crankshaft 28 via a timing transmission 61. This timing transmission 61
The drive sprocket 62 fixed to the crankshaft 28 adjacent to the outside of the left bearing 27 that supports the crankshaft 28, the driven sprocket 63 fixed to one end of the camshaft 38, and the two sprockets 62, 63 An endless timing chain 64 is wound around the camshaft 3 to reduce the rotation of the crankshaft 28 with a reduction ratio of 1/2.
8 can be transmitted. Timing chain 64
Are accommodated in a timing chain passage 65 formed on one side wall of the cylinder block 22.

The cylinder block 22 is arranged so that the axis Ab of the cylinder bore 22a is offset downward by a distance S with respect to the axis Ac of the crankshaft 28, and the cylinder head 23 moves the axis Am of the camshaft 38 to the cylinder bore. It is arranged so as to be offset by a distance S ′ below the axis Ab of 22a. Due to such two-stage offset, the cylinder head 23 is moved to the cylinder bore 22.
a, the cylinder head 23 is displaced downward by two steps with respect to the crankcase 21 while maintaining the inclined state of the cylinder head 23.
And the space 66 between the backbones 2 can be effectively enlarged.

Referring again to FIGS. 1 and 3, the intake system 70 of the engine E is disposed in the space 66. An intake pipe 71 constituting a part of the intake system 70 is provided with an intake port 32.
Is connected to the upper surface of the cylinder head 23 so as to communicate with the cylinder head 23.
The intake pipe 71 rises upward from the cylinder head 23 and then bends forward along the lower surface of the backbone 2, and a side draft type carburetor 72 is connected to its end, that is, the upstream end. Air cleaner 7 at intake port
3 are connected. Thus, the intake system 70 is configured.

Since the space 66 between the cylinder head 23 and the backbone 2 where the intake system 70 is provided is enlarged as described above, the radius of curvature of the bent portion of the intake pipe 71 is set large. As a result, the intake resistance in the intake pipe 71 is reduced, so that the engine output can be improved and the fuel efficiency can be improved.

In addition, the axis Ab of the cylinder bore 22a
Is inclined with a small forward inclination α as before, so that the timing chain passage 65 is also inclined. Therefore, the cylinder head 23 is moved from the oil reservoir at the bottom in the crankcase 21 by an oil pump (not shown).
After the lubrication, the oil supplied to the valve operating mechanism 36 naturally flows down the timing chain passage 65 and can return to the oil reservoir.

According to the offset of the axis Ab of the cylinder bore 22a with respect to the axis Ac of the crankshaft 28,
At the maximum pressure in the expansion process of the engine E, the piston 2
9 is reduced, the sliding frictional resistance of the piston 29 is reduced, and a further improvement in fuel economy can be achieved.

An exhaust pipe 81 communicating with the exhaust port 33 is connected to the lower surface of the cylinder head 23.
1 is bent rearward and extends, and is connected to a muffler (not shown) arranged on one side of the rear wheel 4r.

2 and 3, a rotor 76 of a generator 75 is keyed to one end of the crankshaft 28.
The rotor 76 and a starting gear 77 rotatably supported on the crankshaft 28 are connected via a one-way clutch 78. The one-way clutch 78 is capable of transmitting a rotational force in only one direction from the starting gear 77 to the rotor 76. A starting motor 80 for driving the starting gear 77 via a reduction gear train 79 is a crank motor. It is attached to the upper part of the crankcase 21 on the front side of the shaft 28. And
The front hanger boss 24 for suspending the engine is disposed immediately after the starting motor 80 and substantially immediately above the crankshaft 28.

Thus, the starting motor 80 is provided with a relatively large space 66 between the crankcase 21 and the backbone 2.
Can be installed on the crankcase 21 while utilizing the Moreover, the upper hanger boss 24 has the engine E
, And is less affected by the vibration of the engine E, and therefore, the transmission of vibration from the upper hanger boss 24 to the backbone 2 is also reduced, which can contribute to an improvement in riding comfort.

2 and 3, the crankcase 2
1 includes an input shaft 86 arranged in parallel with the crankshaft 28.
And a transmission 85 having an output shaft 87 is accommodated. At that time, the input and output shafts 86 and 87 are
4, 94 '; and 95, 95' are respectively supported on the crankcase 21. A plurality of speed change gear trains 88 _{1 to} 88 n are formed between the input and output shafts 86 and 87.
The power generated by the crankshaft 28 is supplied to the input shaft 8 via a centrifugal clutch 89, a primary reduction gear train 90 and a speed change clutch 91.
6 and from this input shaft 86 to the output shaft 87 via one selected transmission gear train, and further to a chain transmission 92 disposed outside the crankcase 21.
To the rear wheel 4r to drive the rear wheel 4r.

In the transmission 85, the output shaft 87 is
The input shaft 8 is disposed on substantially the same horizontal plane as the crankshaft 28.
6 is arranged above the crankshaft 28 and the output shaft 87 at an intermediate position between the two shafts 28 and 87 so as to be offset from each other. Further, above the input shaft 86, there are transmission gear trains 88 ₁ to 88 ₁ .
A shift drum 93 for selecting 88n is arranged.

In this way, the distance between the crankshaft 28 and the output shaft 87 can be reduced, and the crankcase 21 can be made more compact, and the engine E can be made more compact. In addition, since the front hanger boss 24 occupies a position substantially immediately above the crankshaft 28, the upper wall of the crankcase 21 immediately above the input shaft 86 is caused by the upward offset of the input shaft 86 from the crankshaft 28 and the output shaft 87. Can be prevented from interfering with the front hanger boss 24 even when it is necessary to bulge a part upward.

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

In the second embodiment, a water jacket 96 is formed on the cylinder block 22 and the cylinder head 23 of the engine E. Only the axis Ab of the cylinder bore 22a of the 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 camshaft 38 is disposed on the axis Ab of the cylinder bore 22a. The upper hanger boss 24 is formed integrally with the upper wall of the cylinder block 22. In the intake system 70, a throttle body 172 is provided instead of the carburetor 72 of the previous embodiment, and a fuel injection valve 74 capable of injecting fuel toward the outlet of the intake port 32 is attached to the intake pipe 71 accordingly. Can be

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

Since other structures are substantially the same as those of the previous embodiment, the same reference numerals in FIG. 5 denote the same parts as in the previous embodiment, and a description thereof will be omitted.

The present invention is not limited to the above embodiment, and various design changes can be made without departing from the gist of the present invention.

[0043]

As described above, according to the first aspect of the present invention, the engine body of the engine suspended from the backbone of the vehicle body frame, which is inclined downward and rearward from the head pipe, is mounted on the crankshaft. And the crankcase
A cylinder block that projects forward from the crankcase and is disposed so that the axis of the cylinder bore is inclined forward and upward; and a cylinder head that is joined to the front end of the cylinder block. In a backbone type motorcycle in which the intake system of the engine is arranged in the space between the cylinder blocks, the cylinder block is arranged so that the axis of the cylinder bore is offset downward with respect to the axis of the crankshaft. Is displaced downward with respect to the crankcase while maintaining the inclined state of the axis of the cylinder, the space between the cylinder head and the backbone can be enlarged, and therefore, the bending of the intake system disposed in the space can be reduced. To reduce intake resistance It is possible to improve the output performance and fuel economy. Also, the offset of the axis of the cylinder bore with respect to the axis of the crankshaft causes a decrease in the side thrust acting on the piston at the maximum pressure in the expansion process of the engine, thereby reducing the sliding frictional resistance of the piston.
Further improvement in fuel economy can be achieved.

According to the second feature of the present invention, in addition to the first feature, the axis of the valve operating cam shaft supported by the cylinder head is offset downward with respect to the axis of the cylinder bore. Since the cylinder head is arranged, the cylinder head is displaced two steps downward with respect to the crankcase, so that the space between the cylinder head and the backbone can be further expanded, and the intake system provided in the space can be enlarged. It is possible to effectively reduce the intake resistance by reducing the bending.

According to a third feature of the present invention, the first
Alternatively, in addition to the second feature, a starting motor is mounted on the upper part of the crankcase in front of the crankshaft, and a hanger boss suspended from the backbone is mounted on the upper surface of the crankcase immediately after the starting motor and almost immediately above the crankshaft. As a result, the starting motor can be installed on the crankcase while utilizing the relatively large space between the crankcase and the backbone. Moreover, the hanger boss is arranged at a position close to the center of gravity of the engine, so that it is less affected by the vibration of the engine. Therefore, the transmission of the vibration from the hanger boss to the backbone is also reduced, contributing to an improvement in riding comfort. I can do it.

According to a fourth aspect of the present invention,
In addition to the third feature, the input shaft and the output shaft of the transmission incorporated in the crankcase are arranged in parallel with the crankshaft, respectively, and the input shaft is arranged above the crankshaft and the output shaft. Thus, the distance between the crankshaft and the output shaft is shortened, and the compactness of the crankcase and, in turn, the compactness of the engine can be achieved. In addition, since the hanger boss occupies a position almost directly above the crankshaft, a part of the upper wall of the crankcase immediately above the input shaft bulges upward due to the upward offset of the input shaft from the crankshaft and the output shaft. Even if necessary, interference between the bulging portion and the hanger boss can be avoided.

[Brief description of the drawings]

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

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

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

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

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

[Explanation of symbols]

E: Engine F: Body frame M: Motorcycle S: Downward offset amount of cylinder bore axis from crankshaft line S ':・ Amount of downward offset of camshaft line from cylinder bore axis 1 ・ ・ ・ ・ ・ ・ Head pipe 2 ・ ・ ・ ・ ・ ・ Backbone 20 ・ ・ ・ ・ ・ ・ Engine body 21 ・ ・ ・ ・ ・ ・ Crankcase 22 ・ ・ ・ ・ ・ ・・ Cylinder block 23 ・ ・ ・ ・ ・ ・ ・ Cylinder head 24 ・ ・ ・ ・ ・ ・ ・ Hanger boss (front hanger boss) 28 ・ ・ ・ ・ ・ ・ Crank shaft 38 ・ ・ ・ ・ ・ ・ Cam shaft 66 .... Intake system 80 ... Start motor 85 ... Transmission 86 ... Input shaft 87 ... Output shaft

Claims (4)

[Claims] 1. An engine body (2) of an engine (E) suspended from a backbone (2) extending inclining backward and downward from a head pipe (1) of a body frame (F).
0), a crankcase (21) for supporting the crankshaft (28), and projecting forward from the crankcase (21), and arranged so that the axis (Ab) of the cylinder bore (22a) is inclined forward and upward. Cylinder block (2
2) and a cylinder head (23) joined to the front end of the cylinder block (22). An engine (E) is provided in a space (66) between the cylinder head (23) and the backbone (2). In the backbone type motorcycle provided with the intake system (70) of (1), the cylinder (22) is offset (S) such that the axis (Ab) of the cylinder bore (22a) is offset downward (S) with respect to the axis (Ac) of the crankshaft (28). Block (22) is arranged,
Backbone type motorcycle engine. 2. The backbone type motorcycle engine according to claim 1, wherein the axis (Am) of the valve operating cam shaft (38) supported by the cylinder head (23) is the axis (Ab) of the cylinder bore (22a). ), Wherein the cylinder head (23) is arranged so as to be offset downward (S ') with respect to the engine of the backbone type motorcycle. 3. The engine of a backbone type motorcycle according to claim 1, wherein a starting motor (8) is provided on an upper part of a crankcase (21) in front of the crankshaft (28).
0), and a hanger boss (24) suspended from the backbone (2) is formed on the upper surface of the crankcase (21) immediately after the starting motor (80) and almost immediately above the crankshaft (28). Features a backbone type motorcycle engine. 4. An engine for a backbone type motorcycle according to claim 3, wherein the input shaft (86) and the output shaft (87) of the transmission (85) incorporated in the crankcase (21) are respectively connected to the crankshaft (28). And the input shaft (86) of the crankshaft (28)
And an engine for a backbone type motorcycle, wherein the engine is disposed above the output shaft (87).