JPH0764303B2 - Motorcycle frame - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a frame used in a motorcycle of a chain or belt drive type, and more particularly to a support structure for an engine thereof.

[Conventional technology]

In order to achieve both weight reduction and high rigidity in a motorcycle frame, for example, as shown in Japanese Patent Laid-Open No. 59-156878, an aluminum alloy main frame structure connected to a steering head pipe is used. It is desirable that the vehicle be bifurcated right and left immediately after the steering head pipe to extend rearward, and the engine be disposed below the bifurcated left and right main frame portions.

In the frame shown in the above-mentioned prior art, the left and right side tubes projecting below the respective main frame parts are bridged between the front end part of the main frame part and the rear arm bracket that pivotally supports the rear arm. The engine is supported between the side tube and the rear arm bracket.

[Problems to be Solved by the Invention]

However, according to this frame structure, since side tubes extending in the front-rear direction through the left and right sides of the engine exist below the left and right main frame portions, the side tubes hinder the engine from the side of the frame. It is difficult to load and unload.

Moreover, since the front end of the side tube reaches the vicinity of the steering head pipe at the front end of the frame, the side tube itself becomes large and the frame becomes heavy and large. At the same time, when the engine is mounted on the frame, the side tubes overlap sideways over substantially the entire length of the engine. May be hindered,
In this respect, there is still room for improvement.

Further, in a motorcycle having a frame having the above structure, when transmitting the output of the engine to the rear wheels through a chain, the sprocket with which the chain meshes is arranged at the rear end on either the left or right side of the crankcase of the engine. As a result, it is possible for this sprocket to be in close proximity to the engine support on the frame.

Then, when the chain is strongly pulled due to sudden acceleration or engine braking, the reaction force of this chain is transmitted to the sprocket of the engine, so the load accompanying the reaction force is applied to the support part of the engine near the sprocket. It becomes easier to concentrate.

Therefore, while the motorcycle is traveling, the supporting portion of the engine in the frame receives a larger load than the other portions of the frame, and it is necessary to give sufficient consideration especially to the rigidity of the frame.

The present invention has been made based on such a situation, and the load caused by the reaction force of the winding transmission body is applied to the entire main frame structure without impairing the workability in loading and unloading and maintaining the engine. It is an object of the present invention to provide a motorcycle frame which can be widely dispersed in the vehicle and can sufficiently secure the supporting rigidity of the engine.

[Means for Solving the Problems]

In order to achieve the above object, the present invention connects a steering head pipe pivotally supporting a front fork and a pair of left and right rear arm brackets pivotally supporting a front end of a rear arm by a hollow main frame structure. An engine having a crankcase and a cylinder connected to the crankcase is arranged below the frame structure. The engine has an endless winding transmission body for transmitting engine power to either side of the crankcase. It is assumed that the motorcycle has a sprocket that is transmitted to the rear wheels and the rear end of the crankcase is supported by the rear arm bracket near the sprocket.

When viewed from the side, the main frame structure has a pair of left and right main frame parts extending obliquely downward and rearward from the steering head pipe toward the rear arm bracket in a substantially straight line. Is formed in a vertically long rectangular pipe shape, and one rear arm bracket positioned on the sprocket side is provided with a reinforcing rod extending from the vicinity of the support portion of the crankcase toward the front side of the sprocket. The front end of the reinforcing rod is connected to the lower surface of one main frame portion located on the sprocket side, and the lower end of the other main frame portion located on the opposite side of the sprocket is , An engine support portion projecting downward is provided, and the projecting end portion of the engine support portion and the auxiliary Between the front end portion of the rod, it is characterized in that the left and right sides of the cylinder and each support.

[Action]

According to this structure, the left and right main frame parts are formed in a vertically long rectangular pipe shape, and the main frame parts have high rigidity against bending in the up and down direction. It can receive the main load. Therefore, it is possible to omit a frame component member that extends laterally of the engine in the front-rear direction over the entire length thereof, or holds the engine from below, and the weight of the frame can be reduced by that amount. A wide range from the side to the bottom of the engine can be opened.

In particular, on the side of the frame opposite to the sprocket of the engine, there is only the engine support portion extending downward from the lower surface of the main frame portion, and since the left and right side surfaces of this frame are different from each other, the engine A wider area is opened from the side to the front and the bottom. For this reason, the frame does not interfere with the removal and maintenance work of the engine, and the workability is improved.

Moreover, according to the above configuration, since the reinforcing rod exists on the side of the sprocket of the frame, even if the load due to the reaction force of the winding transmission body is applied to the support portion of the crankcase in the rear arm bracket, this load is applied. The front part of the main frame part can be escaped via the reinforcing rod. Therefore, the load transmitted from the crankcase to the rear arm bracket can be dispersed over a wide range of the main frame structure, and the load burden on the rear arm bracket can be reduced.

〔Example〕

The present invention will be described below based on an embodiment shown in the drawings.

In the figure, reference numeral 1 is a frame made of aluminum alloy, and a steering head pipe 2 is provided at the front end thereof. A front fork 3 is pivotally supported on the steering head pipe 2, and a front wheel 3a is attached to a lower end portion of the front fork 3.
Is supported.

A main frame structure 4 extending diagonally downward and rearward is connected to the steering head pipe 2. The main frame structure 4 is made by assembling an aluminum plate into a hollow box shape. As shown in FIGS. 2 and 3, the main frame structure 4 expands in the left-right direction as it goes rearward of the steering head pipe 2, and It is bifurcated at the rear of the steering head pipe 2.

That is, the main frame structure 4 includes a hollow box-shaped portion 5 connected to the steering head pipe 2, and a pair of left and right main frame portions 6a and 6b extending rearward from both left and right side portions at the rear end of the box-shaped portion 5. ing. Main frame part 6a, 6b
Is a box-shaped portion 5 as is clear from FIGS.
It has a vertically long rectangular pipe shape whose width dimension in the left-right direction is narrower than that in the left-right direction, and particularly high rigidity can be obtained with respect to the load in the vertical direction.

Left and right seat rails 7 extending rearward are connected to the upper surfaces of the intermediate portions of the main frame portions 6a and 6b, and between the seat rail 7 and the rear ends of the main frame portions 6a and 6b, The back stay 8 is installed.

Left and right rear arm brackets 9a, 9b are integrally connected to the rear end portions of the main frame portions 6a, 6b by welding. Between the lower ends of these rear arm brackets 9a, 9b,
Connected by cross member 23.

A front end portion of a rear arm 11 is swingably supported between the rear arm brackets 9a and 9b via a pivot shaft 11a, and a rear wheel 10 is supported on a rear end portion of the rear arm 11. Therefore, the main frame structure 4 connects the steering head pipe 2 and the rear arm brackets 9a, 9b in a substantially straight line shape in a side view.

The engine 12 is arranged below the main frame portions 6a and 6b. The engine 12 of this embodiment is a crankcase.
A water-cooled V-type four-cylinder engine having a cylinder 13 and a first cylinder 14 and a second cylinder 15 connected to the front end of the crankcase 13. The first cylinder 14 and the second cylinder 15 have side It is arranged in a V shape so as to expand toward the front when viewed from the direction.

That is, as shown in FIGS. 4 and 5, the first cylinder 14 is laid down so that its cylinder axis O1 is substantially horizontal, and the second cylinder 15 is laid down on its cylinder axis O2.
Is inclined at an angle so as to direct the steering head pipe 2. Therefore, the second cylinder 15
Above the first cylinder 14, it is arranged in such a posture as to follow the inclinations of the left and right main frame portions 6a, 6b.

As shown in FIG. 2 and FIG. 3, the main frame portion 6 is
The arrangement interval of a and 6b is set to be wider than the width dimension of the engine 12 in the left-right direction in the portion passing above the engine 12. The upper portion of the second cylinder 15 is inserted between the main frame portions 6a and 6b, and the remaining portion of the second cylinder 15 excluding the upper portion, most of the crankcase 13 and the above. The first cylinder 14 projects below the main frame portions 6a and 6b.

As shown in FIGS. 1 and 4, a drive sprocket 16 for outputting engine power is arranged on the left side surface of the rear end of the crankcase 13. The drive sprocket 16 is located immediately in front of the left rear arm bracket 9a, and between the drive sprocket 16 and the driven sprocket 17 mounted on the hub of the rear wheel 10, an endless chain as a winding transmission body is formed. 18 are wound.

Such an engine 12 is suspended and supported by the main frame portions 6a and 6b as described below.

That is, as shown in FIGS. 2 and 3, engine support portions 20a, 20b projecting downward are provided on the lower surface of the widened portions of the main frame portions 6a, 6b. . These engine support portions 20a, 20b are located on the left and right sides of the second cylinder 15, as shown in FIGS. 4 and 5.

A reinforcing rod 19 is welded to one engine support portion 20a located on the left side of the frame 1, that is, on the side of the drive sprocket 16 of the engine 12. The reinforcing rod 19
Rear arm bracket 9a on the left from the engine support 20a
The rear arm bracket.
It is welded to 9a. The reinforcing rod 19 is arranged substantially parallel to the main frame portion 6a at a position close to the lower surface of the main frame portion 6a, and as shown in FIG. 4, the second cylinder 15 and the drive sprocket 16 are provided. It passes through the left side of and extends in the front-back direction.

As shown in FIG. 5, the engine support portion 20b on the right side is formed in a substantially triangular shape in a side view, and is tapered toward the lower side of the main frame portion 6b. And the second
The portion of the cylinder 15 exposed below the main frame portions 6a, 6b is interposed between the engine support portion 20b and the front end portion of the reinforcing rod 19, and the second cylinder
Two places on both left and right sides of 15 are fixed via bolts respectively.

Further, between the main frame portions 6a, 6b, a support projection 21 provided on the upper surface of the crankcase 13 is interposed, and is supported via a bolt 22, and the rear arm brackets 9a, 9b are provided. Left and right boss portions 24 projecting from the rear surface of the crankcase 13 are bolted to the cross member 23.

Therefore, the main frame portions 6a and 6b are connected to the second cylinder 1
5a and the support part 25a that supports the crankcase 13 at three points
~ 25c, rear arm bracket 9a,
9b includes a support portion 25d that supports the rear end of the crankcase 13. The supporting portion 25d that supports the rear end of the crankcase 13 is close to the connecting end of the drive sprocket 16 and the reinforcing rod 19.

Therefore, the reinforcing rod 19 is led out toward the front from the vicinity of the support portion 25d of the engine 12 near the drive sprocket 16, and the support portion 25d and the other support portion 25a located in front of the drive sprocket 16. It is connected to 25b.

Further, as shown in FIGS. 4 and 5, when the engine 12 is suspended on the main frame portions 6a, 6b, the upper portion of the second cylinder 15 is located between the left and right main frame portions 6a, 6b. It is located below the bottom of the fuel tank 26. Therefore, the upper part of the second cylinder 15 and the fuel tank
26, and between the left and right main frame portions 6a, 6b, a passage 30 extending in the front-rear direction of the engine 12 is formed, and the exhaust pipe 31 of the second cylinder 15 is located in the passage 30. Has been done.

In FIGS. 4 and 5, reference numeral 27 is a sheet, and 28 is a radiator.

According to such a configuration, the main frame portions 6a, 6b extending forward and backward above the engine 12 are formed in a vertically long rectangular pipe shape, and the main frames 6a, 6b are resistant to bending in the vertical direction. Due to the high rigidity, the engine support parts 20a, 20b supporting the engine 12 can be provided on the lower surfaces of the main frame parts 6a, 6b.

Therefore, the left and right main frames 6a and 6b are
It is possible to receive the main load of the engine 12 and to extend the front and back of the side of the engine 12 over the entire length, or to omit the frame component that holds the engine 12 from below.

Therefore, not only the weight of the frame 1 can be reduced, but also the side and lower portions of the engine 12 are widely opened,
It is possible to easily load and unload the engine 12 to and from the frame 1.

Drive sprocket for engine 12, especially in frame 1
On the side opposite to 16, there is only an engine support portion 20b extending downward from the lower surface of the main frame portion 6b,
Since the left and right side surfaces of the frame 1 are different from each other, the range from the right side of the engine 12 to the front side and the lower side thereof is opened wider. Therefore, the workability is improved without the frame 1 interfering with the operation of the engine 12 such as the attachment / detachment of the cylinder of the engine 12 and the maintenance work of the crankcase 13.

Furthermore, in the case of the present embodiment, the engine support portions 20a and 20b are
Since the main frame portions 6a and 6b are provided so as to project in a portion formed wider than the engine 12, it is not necessary to form these engine support portions 20a and 20b in a shape that avoids interference with the engine 12. . Therefore, the shapes of the engine support portions 20a and 20b can be simplified and can be made compact, which is convenient for reducing the weight of the frame 1.

At the same time, the upper portion of the second cylinder 15 supported by the engine supporting portions 20a and 20b has a main frame portion.
Since it enters between 6a and 6b, the main frame part 6a,
The 6b and the second cylinder 15 do not significantly shift in the vertical direction. Therefore, even if the engine support parts 20a and 20b are used,
The amount of downward projection can be reduced, and these engine support portions 20a and 20b can be made compact. Therefore, the rigidity of the engine support portions 20a and 20b themselves can be sufficiently ensured.

Further, according to the above configuration, since the supporting portion 25d of the crankcase 13 near the drive sprocket 16 and the engine supporting portion 20a of the one main frame 6a are connected by the reinforcing rod 19, rapid acceleration or engine braking is performed. Even if the chain 18 is pulled strongly by the chain 18 and the load due to the reaction force of the chain 18 is applied to the support portion 25d, this load is applied through the reinforcing rod 19 to the engine support portion 20d.
It is released to a and one main frame portion 6a.

Therefore, the load applied from the crankcase 13 to the supporting portion 25d can be dispersed over a wide range of the main frame structure 4, and the load on the supporting portion 25d including the rear arm brackets 9a and 9b can be reduced. . Therefore, the support portion 25d can be prevented from being damaged, and the support portion 2d can be prevented.
The rigidity around 5d can be increased to firmly support the engine 12.

In the above embodiment, the power of the engine is transmitted to the rear wheels via the chain, but a toothed belt may be used instead of the chain.

〔The invention's effect〕

According to the present invention described in detail above, the left and right main frame portions have high rigidity against bending in the vertical direction, so that the main load of the engine can be received by these main frame portions and the lateral side of the engine can be supported. It is possible to omit a frame component that extends in the front-rear direction over its entire length or holds the engine from below. Therefore, the weight of the frame can be reduced, and the range of the engine from the side to the bottom can be widened. In particular, on the side of the frame opposite to the sprocket of the engine, there is only the engine support portion extending downward from the lower surface of the main frame portion, and since the left and right side surfaces of this frame are different from each other, the engine A wider area is opened from the side to the front and the bottom. Therefore, the frame does not interfere with the loading and unloading work and the maintenance work of the engine on the frame, and the workability is improved.

In addition, when a load due to the reaction force of the wound transmission body is applied around the rear arm bracket, this load can be released to the main frame portion through the reinforcing rod. Can be dispersed over a wide range. Therefore, it is possible to reduce the load burden on the support portion of the engine including the rear arm bracket, prevent damage to the support portion, and increase the rigidity around the support portion to firmly support the engine.

[Brief description of drawings]

The drawings show one embodiment of the present invention, FIG. 1 is a side view of a frame, FIG. 2 is a front view of the frame, FIG. 3 is a plan view of the frame, and FIGS. FIG. 2 is a side view of a motorcycle, respectively. 2 …… Steering head pipe, 4 …… Main frame structure, 6a, 6b …… Main frame part, 9a, 9b …… Rear arm bracket, 10 …… Rear wheel, 11 …… Rear arm, 12 …… Engine, 13 …… Crankcase, 15 ... Cylinder (second cylinder), 16 ... Sprocket (drive sprocket), 18 ... Winding transmission body (chain), 19 ... Reinforcing rod, 20b ... Engine support, 25d ... Support section.

Claims (1)

[Claims] 1. A hollow main frame structure connects between a steering head pipe that pivotally supports a front fork and a pair of left and right rear arm brackets that pivotally supports a front end of a rear arm, and below the main frame structure. An engine having a crankcase and a cylinder connected to the crankcase is arranged, and the engine is a sprocket that transmits engine power to a rear wheel through an endless winding transmission body on either the left or right side surface of the crankcase. In a frame of a motorcycle having a rear end portion of the crankcase supported by the rear arm bracket near the sprocket, the main frame structure has the steering head pipe when viewed from the side. From the above toward the rear arm bracket diagonally downward It has a pair of left and right main frame parts that extend in a straight line, and these main frame parts are formed into a vertically long rectangular pipe shape, and one of the rear arm brackets located on the sprocket side is provided with the crank part. A reinforcing rod extending from the vicinity of the supporting portion of the case toward the front of the sprocket is connected, and a front end portion of the reinforcing rod is connected to a lower surface of one main frame portion located on the sprocket side, On the lower surface of the other main frame portion located on the opposite side of the sprocket, an engine support portion protruding downward is provided, and between the protruding end portion of this engine support portion and the front end portion of the reinforcing rod, A motorcycle frame characterized by supporting the left and right sides of the cylinder respectively.