JP4280401B2 - Engine exhaust system support structure for motorcycles - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
According to the present invention, an engine is mounted on a vehicle body frame in front of a rear wheel, and includes an exhaust muffler and an exhaust device connected to an exhaust port provided in an engine body of the engine is automatically supported by the vehicle body frame. More particularly, the present invention relates to an improvement in a support structure for an exhaust device.
[0002]
[Prior art]
In a conventional motorcycle, for example, as disclosed in Japanese Patent Laid-Open No. 5-131963, an exhaust muffler provided in an exhaust device is formed long in the front-rear direction of the motorcycle and is disposed on one side of a rear wheel. Generally, the exhaust port of the engine to which is connected is arranged at a position close to the center line of the vehicle body.
[0003]
[Problems to be solved by the invention]
However, when the exhaust device as described above is supported on the vehicle body frame, the exhaust device is disposed on one side of the vehicle body centerline as a whole, and therefore, at a plurality of locations excluding the portion where the exhaust device is connected to the engine body. The exhaust device needs to be firmly supported on the vehicle body frame, and the number of parts for supporting the exhaust device is increased, and the number of assembling steps for assembling the exhaust device to the vehicle body frame is also increased.
[0004]
The present invention has been made in view of such circumstances, and provides an exhaust device support structure for an engine in a motorcycle that can reduce the number of components and reduce the number of assembly steps when supporting the exhaust device. Objective.
[0005]
[Means for Solving the Problems]
In order to achieve the above object, according to a first aspect of the present invention, an engine is mounted on a vehicle body frame in front of a rear wheel, and includes an exhaust muffler and is connected to an exhaust port provided in the engine body of the engine. In a motorcycle in which an exhaust device is supported by the body frame, the exhaust muffler is formed long in the width direction of the body frame and is disposed between the engine and the rear wheel, and one end of the exhaust muffler and the exhaust port are connected to each other. The upstream end of the first exhaust pipe is connected to the engine body on a straight line connecting the first center of gravity of the first exhaust pipe to be connected to the exhaust muffler and the second center of gravity of the second exhaust pipe connected to the other end of the exhaust muffler. The exhaust muffler is fastened and supported by the vehicle body frame at a second center of gravity.
[0006]
According to such a configuration, the exhaust system is supported on a straight line passing through the center of gravity of the entire exhaust system on the engine body and the body frame of the engine mounted on the body frame. The acting bending load can be reduced, and the exhaust device can be supported with sufficient support strength even when the exhaust device is supported at two front and rear positions. Moreover, of the two locations, the support portion of the first exhaust pipe to the engine body is a connection portion of the exhaust device to the engine body, and the dedicated support portion for supporting the exhaust device supports the exhaust muffler on the vehicle body frame. The number of parts is reduced when supporting the exhaust device, and the number of assembling steps can be reduced accordingly.
[0007]
According to a second aspect of the invention, in addition to the configuration of the first aspect of the invention, a drive chain for transmitting power from the engine to a rear wheel is disposed on one side of the vehicle body center line, The first center of gravity of the first exhaust pipe and the second center of gravity of the exhaust muffler and the second exhaust pipe are arranged on the opposite side of the drive chain with respect to the line. While avoiding interference with the driving force transmission system between the engine and the rear wheels, the exhaust muffler can be placed as close to the engine as possible to reduce the center of gravity while ensuring ground clearance, and the exhaust system can be easily assembled. .
[0008]
In addition to the configuration of the invention described in claim 2, the exhaust gas muffler has one end formed in a planar shape along a vertical plane and closer to the vehicle center line than the drive chain. According to this configuration, the exhaust muffler can be effectively arranged on the side of the space necessary for the swing of the drive chain.
[0009]
DETAILED DESCRIPTION OF THE INVENTION
DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described below based on one embodiment of the present invention shown in the accompanying drawings.
[0010]
1 to 5 show an embodiment of the present invention, FIG. 1 is a side view of a motorcycle, FIG. 2 is an enlarged view of a main part of FIG. 1, and FIG. 3 is a longitudinal side view for showing the inside of a crankcase. 4 is a bottom view taken along arrow 4 in FIG. 2, and FIG. 5 is a sectional view taken along line 5-5 in FIG.
[0011]
First, in FIG. 1, a front fork 17 that pivotally supports a front wheel WF is pivotally supported by a head pipe 16 provided at a front end of a body frame 15 of the motorcycle. A bar handle 18 is connected to the upper end of the front fork 17, and a front fender 19 that covers the front wheel WF is supported by the front fork 17. A rear fork 20 that pivotally supports the rear wheel WR is pivotally supported by a pair of left and right support brackets 40 fixed to the middle portion of the vehicle body frame 15, and a rear cushion 21 is provided between the rear portion of the vehicle body frame 15 and the rear fork 20. Provided.
[0012]
A water-cooled engine E is mounted in an intermediate portion of the body frame 15, and an engine body 22 of the engine E and a radiator 24 supported by the body frame 15 are disposed above the front portion of the engine body 22. An air cleaner 23 supported by the vehicle body frame 15 is disposed above the front portion of the engine body 22. Further, a fuel tank 25 disposed above the engine body 22 and a storage box 26 disposed above the fuel tank 25 so as to be able to store electrical components are supported by the vehicle body frame 15.
[0013]
The front part of the body frame 15, the engine E, the air cleaner 23 and the radiator 24 are covered with a synthetic resin leg shield 29 attached to the body frame 15. The rear portion of the vehicle body frame 15, the fuel tank 25 and the storage box 26 are covered with a synthetic resin rear cover 30 attached to the vehicle body frame 15, and a rear fender 31 covering the rear upper portion of the rear wheel WR is connected to the rear cover 30. Established. A seat 32 is provided on the rear cover 30 so that the upper end opening of the storage box 26 can be opened and closed, and a driver can sit on the seat 32.
[0014]
In FIG. 2, the engine body 22 of the engine E includes a cylinder block 34 having a cylinder bore 33 that substantially extends in the front-rear direction of the body frame 15, a cylinder head 35 fastened to the front portion of the cylinder block 34, and the cylinder block 34. The cylinder block 34 and the crankcase 36 are supported by support brackets 39, 40... Fixed to the vehicle body frame 15.
[0015]
Referring also to FIG. 3, the crankcase 36 includes left and right crankcase halves 37 and 38 that are fastened to each other, and the crankshaft 41 is rotatable by both crankcase halves 37 and 38. Supported.
[0016]
A transmission M is housed and arranged in the crankcase 36. The transmission M includes a main transmission shaft 42 to which power is transmitted from the crankshaft 41, and a sub transmission shaft 43 parallel to the main transmission shaft 42. , A gear train 44 of a plurality of shift stages provided between the main transmission shaft 42 and the sub-transmission shaft 43, and a shift mechanism 45 for selecting and establishing one of the gear trains 44.
[0017]
The main transmission shaft 42 is rotatably supported by the crankcase 36 on the rear side of the crankshaft so that the axis is orthogonal to a substantially horizontal straight line 46 extending in the front-rear direction through the axis of the crankshaft 41. Is supported by the crankcase 36 so as to be rotatable rearward of the main transmission shaft 42 with the axis orthogonal to the straight line 46.
[0018]
One end of the sub-transmission shaft 43 protrudes to the outside through the left crankcase half 37 of the crankcase 36, and a drive sprocket 47 is fixed to one end projecting portion of the sub-transmission shaft 43 so that power is transmitted to the rear wheel WR. An endless drive chain 48 is transmitted around the drive sprocket 47.
[0019]
A chain cover 49 is attached to the outer surface of the left crankcase half 37 so as to cover a bracket for wrapping the drive chain 48 around the drive sprocket 47, and a chain cover covering a part of the drive chain 48 above the rear fork 20. 50 is attached.
[0020]
Referring also to FIG. 4, an exhaust port 51 is provided on the lower side surface of the cylinder head 35 in the engine body 22, and an exhaust device 52 is connected to the exhaust port 51. The exhaust device 52 is disposed between the first exhaust pipe 53 whose upstream end is connected to the exhaust port 51 and the crankcase 36 and the rear wheel of the engine E, and is connected to the downstream end of the first exhaust pipe 53. The exhaust muffler 54 and a second exhaust pipe 55 having an upstream end connected to the exhaust muffler 54 are configured.
[0021]
The exhaust muffler 54 is provided with a casing 54a that has an elliptical cross-sectional shape, is closed at both ends, and is formed long in the width direction of the vehicle body frame 15, and is attached to the main and auxiliary transmission shafts 42 and 43 of the transmission M. The rear wall rear portion 36a of the corresponding crankcase 36 can secure a space for disposing at least a part (a part in this embodiment) of the exhaust muffler 54 below the bottom wall rear portion 36a. Is formed higher than the bottom wall front portion 36b of the crankcase 36 corresponding to the above.
[0022]
By forming the bottom wall front portion 36b of the crankcase 36 lower than the bottom wall rear portion 36a, an oil reservoir 56 is formed at the front portion in the crankcase 36 corresponding to the crankshaft 41, and the oil A suction port 57 for pumping up the oil stored in the reservoir 56 with a pump (not shown) is provided in the crankcase 36 continuously to the bottom wall front portion 36b.
[0023]
In addition, left and right crankcase halves 38 and 39 that jointly constitute the crankcase 36 are provided with partition walls 58 that are curved in accordance with the rotation trajectory drawn by the outer surface of the crankweight 41a included in the crankshaft 41. The partition walls 58 are provided so as to face each other when the halves 38 and 39 are joined, and the partition walls 58 are formed between the oil level L stored in the oil reservoir 56 and the crank weight 41 of the crankshaft 41. It is formed so as to intervene.
[0024]
Referring also to FIG. 5, the first exhaust pipe 53 of the exhaust device 52 is connected to the engine on the right side of the vehicle body frame 15 from the exhaust port 51 provided on the lower side wall of the cylinder head 35 on the right side of the vehicle body frame 15. The portion extending rearward through the lower portion of the main body 22 and corresponding to the rear portion of the crankcase 36 is bent to the left side of the vehicle body frame 15 through the lower portion of the rear bottom wall 36a. The downstream end of the exhaust pipe 53 is connected to one end of the exhaust muffler 54. The second exhaust pipe 55 is connected to the other end of the exhaust muffler 54, and is bent in a substantially L shape so that the downstream end faces rearward.
[0025]
Moreover, the first exhaust pipe 53, the exhaust muffler 54, and the second exhaust pipe 55 have a straight line 59 connecting the first center of gravity G1 of the first exhaust pipe 53 and the second center of gravity G2 of the exhaust muffler 54 and the second exhaust pipe 55. The cylinder head 35 of the engine body 22 is arranged on the straight line 59 so that the upstream end of the first exhaust pipe 52 on the straight line 59 is a plurality of bolts 70 and nuts 71. To be concluded. A support stay 61 is fixed to the upper part of the exhaust muffler 54, and the support stay 61 is attached to the right support bracket 40 of the pair of left and right support brackets 40, 40 at a portion corresponding to the second center of gravity G2. 72 and a nut 73. That is, the exhaust device 52 is supported by the vehicle body frame 15 at two locations, that is, a connecting portion to the cylinder head 35 at the upstream end of the first exhaust pipe 53 and a support portion of the exhaust muffler 54 to the support bracket 40.
[0026]
Meanwhile, the drive chain 48 for transmitting the power from the engine E to the rear wheel WR is arranged on the left side of the vehicle body center line 60, whereas the drive chain 48 is opposite to the drive chain 48, that is, on the vehicle body center line 60. On the right side, the first center of gravity G1 of the first exhaust pipe 53 and the second center of gravity G2 of the exhaust muffler 54 and the second exhaust pipe 55 are arranged, and a straight line 59 connecting the centers of gravity G1, G2 The vehicle is substantially parallel to the vehicle body center line 60 at a position close to the right side of the center line 60.
[0027]
Further, one end of the exhaust muffler 54 is formed in a planar shape along the vertical plane, and is disposed closer to the vehicle body center line 60 than the drive chain 48.
[0028]
Two pairs of support bosses 62, 63,... Are formed integrally on the bottom surface of the bottom wall rear portion 36a of the crankcase 36. The support bosses 62, 63,. The step holder 64 formed so as to raise both the left and right ends upward is fastened. Steps 65 and 65 are attached to the left and right ends of the step holder 64 so that the step holder 64 can be folded up in a non-use state. Thus, since the bottom wall rear portion 36a of the crankcase 36 is at a relatively high position, the difference between the fastening position of the step holder 64 to the crankcase 36 and the positions of the left and right steps 65, 65 is relatively small. Tesumu. Therefore, it is possible to relatively reduce the amount of start-up at the left and right ends of the step holder 64 to reduce the strength load acting on the step holder 64, eliminating the need for a member that reinforces the step holder 64, and the like. The holder 64 can be reduced in weight.
[0029]
Further, a stand support member 66 is fastened to a portion near the left end of the step holder 64, and a stand 67 for supporting the motorcycle in a stopped state can be lifted up and connected to the stand support member 66. Is done.
[0030]
Next, the operation of this embodiment will be described. The bottom wall rear portion 36a of the crankcase 36 corresponding to the main and auxiliary transmission shafts 42 and 43 provided in the transmission M housed and arranged in the crankcase 36 is the bottom wall. It is formed higher than the bottom wall front portion 36b of the crankcase 36 corresponding to the crankshaft 41 so as to ensure a space for disposing at least a part of the exhaust muffler 54 below the rear portion 36a. Accordingly, the bottom of the front portion of the crankcase 36 is deeper than the rear portion, and oil can be stored relatively deeply in a relatively narrow space only on the front portion side of the crankcase 36. As a result, it is possible to efficiently pump oil with a simple pumping structure while reducing the amount of oil stored in the crankcase 36 as much as possible.
[0031]
Moreover, since at least a part of the exhaust muffler 54 is disposed below the rear portion 36a of the bottom wall of the crankcase 36, the crankcase 36 is warmed by the radiant heat from the exhaust muffler 54, so that the amount of oil is relatively small. Together with this, the warm-up performance of the engine E can be improved by quickly raising the temperature of the oil.
[0032]
In addition, the crankcase 36 is formed with a partition wall 58 that is bent in accordance with the rotation locus drawn by the outer surface of the crankweight 41 a included in the crankshaft 41 at the front portion in the crankcase 36 corresponding to the crankshaft 41. Further, it is provided so as to be interposed between the oil level L of the oil stored in the oil reservoir 56 and the crank weight 41a. For this reason, it is possible to prevent the oil from being stirred by the crank weight 41a as much as possible, and to reduce fuel consumption by reducing the friction loss of the engine E.
[0033]
An exhaust muffler 54 is formed long in the width direction of the vehicle body frame 15 and is disposed between the engine E and the rear wheel WR. The exhaust muffler 54 is connected to one end of the exhaust muffler 54 and the exhaust port 51 of the cylinder head 35. The upstream end of the first exhaust pipe 53 is on the engine body 22 on a straight line 59 that connects the one center of gravity G1 to the exhaust muffler 54 and the second center of gravity G2 of the second exhaust pipe 55 connected to the other end of the exhaust muffler 54. The exhaust muffler 54 is supported by the vehicle body frame 15 at the second center of gravity G2.
[0034]
That is, the exhaust device 52 is supported on a straight line 59 that passes through the center of gravity of the entire exhaust device 52 by the engine body 22 and the vehicle body frame 15 of the engine E mounted on the vehicle body frame 15. The acting bending load can be reduced, and the exhaust device 52 can be supported with sufficient support strength even when the exhaust device 52 is supported at two front and rear positions.
[0035]
In addition, the support portion of the first exhaust pipe 53 to the cylinder head 35 among the two locations is a connection portion to the engine body 22 of the exhaust device 52, and the dedicated support portion for supporting the exhaust device 52 is an exhaust muffler. This is one of the portions that support the body frame 15 on the body 54. In addition, a support stay 61 fixed to the exhaust muffler 54 is fastened to one of a pair of support brackets 40 and 40 for supporting the engine body 22 of the engine E to the vehicle body frame 15, so that the exhaust muffler 54 is attached to the vehicle body frame 15. One support bracket 40 is used in common so that it can be supported by. Therefore, the number of parts can be reduced in supporting the exhaust device 52, and the number of assembling steps can be reduced accordingly.
[0036]
A drive chain 48 for transmitting power from the engine E to the rear wheel WR is disposed on the left side of the vehicle body center line 60, and the first exhaust pipe 53 is disposed on the opposite side of the vehicle body center line 60 from the drive chain 48. Since the first center of gravity G1 and the exhaust muffler 54 and the second center of gravity G2 of the second exhaust pipe 55 are disposed, the exhaust muffler 54 is disposed while avoiding interference with the driving force transmission system between the engine E and the rear wheel WR. The center of gravity can be lowered as close as possible to the engine E while ensuring a ground clearance, and the exhaust device 52 can be easily assembled.
[0037]
Further, one end of the exhaust muffler 54 is formed in a planar shape along the vertical plane and is disposed closer to the vehicle body center line 60 than the drive chain 48. Therefore, on the side of the space necessary for the swinging of the drive chain 48, The exhaust muffler 54 can be effectively arranged.
[0038]
Although the embodiments of the present invention have been described above, the present invention is not limited to the above-described embodiments, and various design changes can be made without departing from the present invention described in the claims. It is.
[0039]
For example, in the above embodiment, the engine E is a four-cycle engine, but the present invention can also be applied to an exhaust device of a two-cycle engine mounted on a motorcycle.
[0040]
【The invention's effect】
As described above, according to the first aspect of the present invention, the exhaust device is supported by the engine mounted on the vehicle body frame and the vehicle body frame on a straight line passing through the center of gravity of the entire exhaust device. It is possible to reduce the bending load acting on the support portion, and to support the exhaust device with sufficient support strength even at the support of two places before and after the exhaust device. Moreover, the dedicated support portion for supporting the exhaust device is one portion of the portion for supporting the exhaust muffler on the vehicle body frame, reducing the number of parts for supporting the exhaust device, and accordingly reducing the assembly man-hour. be able to.
[0041]
According to the second aspect of the present invention, the center of gravity can be lowered while ensuring the ground clearance by making the exhaust muffler as close as possible to the engine while avoiding interference with the driving force transmission system between the engine and the rear wheels. Assembling of the exhaust device is facilitated.
[0042]
Furthermore, according to the third aspect of the present invention, the exhaust muffler can be effectively disposed on the side of the space necessary for swinging the drive chain.
[Brief description of the drawings]
FIG. 1 is a side view of a motorcycle.
FIG. 2 is an enlarged view of a main part of FIG.
FIG. 3 is a vertical side view for showing the inside of the crankcase.
4 is a bottom view taken along arrow 4 in FIG. 2;
5 is a cross-sectional view taken along line 5-5 of FIG.
[Explanation of symbols]
15 ... body frame 22 ... engine body 48 ... drive chain 51 ... exhaust port 52 ... exhaust device 53 ... first exhaust pipe 54 ... exhaust muffler 55 ... second Exhaust pipe 59 ... straight line 60 ... vehicle body center line G1 ... first center of gravity G2 ... second center of gravity E ... engine WR ... rear wheel

Claims (3)

The engine (E) is mounted on the vehicle body frame (15) in front of the rear wheels (WR) and includes an exhaust muffler (54) and an exhaust port (51) provided in the engine body (22) of the engine (E). In the motorcycle in which the exhaust device (52) connected to the vehicle body frame (15) is connected,
The exhaust muffler (54) is formed long in the width direction of the vehicle body frame (15) and disposed between the engine (E) and the rear wheel (WR). One end of the exhaust muffler (54) and the exhaust port ( 51) of the first exhaust pipe (53), the second center of the second exhaust pipe (55) connected to the exhaust muffler (54) and the other end of the exhaust muffler (54). The upstream end of the first exhaust pipe (53) is fastened to the engine body (22) on a straight line (59) connecting the center of gravity (G2), and the exhaust muffler (54) is connected to the vehicle body frame (2) at the second center of gravity (G2). 15) A structure for supporting an exhaust system of an engine in a motorcycle.   A drive chain (48) for transmitting power from the engine (E) to the rear wheels (WR) is disposed on one side of the vehicle body center line (60), and the drive chain (48 The first center of gravity (G1) of the first exhaust pipe (53) and the second center of gravity (G2) of the exhaust muffler (54) and the second exhaust pipe (55) are disposed on the opposite side of the first exhaust pipe (53). The engine exhaust device support structure for a motorcycle according to claim 1.   3. The exhaust muffler (54) according to claim 2, wherein one end of the exhaust muffler (54) is formed in a planar shape along a vertical plane and is disposed closer to the vehicle body center line (60) than the drive chain (48). Engine exhaust system support structure for motorcycles.

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