JP3160727B2 - Small motorcycle - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a small motorcycle having an exhaust purification device for supplying secondary air to an exhaust system of a unit swing engine.

[0002]

2. Description of the Related Art In motorcycles, an exhaust system of an engine includes:
Some include an exhaust purification device that supplies secondary air for reburning unburned components such as HC and CO contained in exhaust gas in the exhaust system.

In this exhaust gas purifying apparatus, when an engine is operated, secondary air purified in an intake system by an exhaust arterial pressure generated in the exhaust system is supplied to the exhaust system through a secondary air supply pipe. Some secondary air supply pipes include a control unit having a control valve for controlling the supply amount of secondary air.

[0004]

By the way, it is conceivable that a small motorcycle such as a scooter may be provided with such an exhaust gas purifying device. However, in the scooter, a unit swing engine is supported on a body frame so as to be vertically movable. ing. For this reason, when the unit swing engine moves up and down, the control valve for controlling the supply amount of the secondary air may flutter, which may adversely affect the control of the supply of the secondary air.

In order to prevent this, it is conceivable to fix the control unit on the vehicle body frame side. However, in such a case, the piping of the secondary air supply pipe becomes complicated.

It is an object of the present invention to provide a small motorcycle in which piping is easy and vertical movement of a unit swing engine does not adversely affect supply of secondary air. .

[0007]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, the present invention provides a unit swing engine supported on a body frame so as to be vertically movable with a pivot shaft as a fulcrum. In a small motorcycle equipped with an exhaust purification device for supplying air, a control unit for controlling the supply of the secondary air is mounted on a unit swing engine, and a valve shaft of the control valve is set in parallel with the pivot shaft in a coaxial direction. It is characterized by doing.

[0008]

According to the present invention, the control unit having the control valve for controlling the supply of the secondary air is mounted on the unit swing engine, and the control unit moves up and down integrally with the unit swing engine up and down. The valve shaft is set parallel to the pivot axis of the unit swing engine in the coaxial direction, so that the control valve does not flutter and does not adversely affect the supply of the secondary air.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below in detail with reference to the accompanying drawings. 1 is a side view of a scooter-type motorcycle to which the present invention is applied, FIG. 2 is a plan view of the scooter-type motorcycle, and FIG. 3 is a plan view showing the arrangement of a suspension and a control unit of a unit swing engine. 4 is a side view of the unit swing engine, FIG. 5 is a sectional view of a cylinder portion of the unit swing engine, FIG. 6 is an exploded view showing a connection portion of a secondary air supply pipe, and FIG. 7 is a sectional view of a control unit.

In FIG. 1, reference numeral 1 denotes a vehicle body frame, and a steering shaft 3 is provided on a head pipe 2 of the vehicle body. A front fork 4 is provided below the steering shaft 3 via a bracket 5. A front wheel 6 is supported on a lower portion of the front fork 4, and a handle 7 is mounted on an upper portion of the steering shaft 3. The handle portion is covered with a handle cover 8.

A main frame 9 is connected to the head pipe 2. The main frame 9 extends obliquely rearward and downward so as to form a footrest floor 10, and further bends and extends horizontally rearward. The front cover 11 covers from the head pipe 2 to the front central portion of the main frame 9. The main frame 9 is covered with a floor cover 12, and a pair of right and left rear frames 13 is connected to a rear portion of the main frame 9. The rear frame 13 horizontally extends rearward, rises upward, and further extends rearward. The rear frame 13 is covered with a rear cover 14.

The rising portion 1 of the pair of right and left rear frames 13
Each of the brackets 3a is provided with two brackets 15 on the left and right sides, and the unit swing engine 21 is supported by the brackets 15 via link members 16 so as to be vertically swingable. The link member 16 includes a cylindrical portion 17 composed of an inner cylinder 17a, an outer cylinder 17b, and a rubber bush 17c between the two, and a plate member 17d fixed to the outer cylinder 17b of the cylindrical portion 17.

A support bolt 18 is inserted through the inner cylinder 17a, so that one end of the link member 16 is
Supported by Plate member 17 of a pair of left and right link members 16
A pivot shaft 19 penetrates and is provided between d. The pivot shaft 19 supports a bracket 22 of a unit swing engine 21 via a buffer member 20.

The cushioning member 20 includes an inner cylinder 20a, an outer cylinder 20b, and a rubber bush 20c between the inner cylinder 20a and the inner cylinder 20a. The inner cylinder 20a is inserted into the pivot shaft 19 via the cylinder 23, and the unit swings to the outer cylinder 20b. A bracket 22 of the engine 21 is pivotally supported.

The unit swing engine 21 is a four-cycle engine. The unit swing engine 21 includes a crankcase 24 and a crankcase 2.
4 and a cylinder 25 extending forward from the crankcase 2
4 comprises a transmission case 26 extending rearward from one side. The bracket 2 is mounted on the upper part of the crankcase 24.
2 is integrally formed, and a cylinder 25 extending forward from the crankcase 24 is configured by connecting a cylinder block 27 connected to the crankcase 24 and a cylinder head 28 to each other.

A rear wheel 29 is supported by a rear portion of the transmission case 26 via a rear wheel shaft 30, and a rear end 26a of the transmission case 26 is supported by the rear frame 13 via a rear cushion 31. On the opposite side of the transmission case 26 across the supported rear wheel 29, there is provided an arm member 32 connecting the crankcase 24 and the rear wheel shaft 30. The rear end 32a of the arm member 32 is interposed via a rear cushion 33. Supported by the rear frame 13.

A storage box 34 is located above the rear wheel 29.
And a helmet 35 can be stored in the storage box 34. A fuel tank 36 is disposed in front of the storage box 34 above the cylinder 25 of the unit swing engine 21, and a front seat 37 is provided above the fuel tank 36 so as to cover the front seat 37. A rear seat 38 is disposed behind the front seat 37. The rear seat 38 covers an upper portion of the storage box 34, and has an inclined surface on the front side of the rear sheet 38. Are joined to the rear slope portion of the front sheet 37 without gaps. The rear seat 38 can be opened and closed rearward.

The cylinder 25 of the unit swing engine 21
An intake passage 39 is formed in the cylinder head 28 that constitutes the above-mentioned structure, and an intake pipe 40 is connected to the intake passage 39. A carburetor 41 is connected to the intake pipe 40. The carburetor 41 is disposed above the crankcase 24. An air cleaner 43 extending to the left rear of the vehicle body via a duct 42 is connected to the carburetor 41. Have been. The air cleaner 43 is disposed on the left side of the vehicle body along a position above the transmission case 26 of the unit swing engine 21.

An exhaust passage 44 is formed in the cylinder head 28 of the cylinder 25, and an exhaust pipe 45 is connected to the exhaust passage 44. The exhaust pipe 45 extends along the lower right side of the unit swing engine 21. Extending backwards. A muffler 46 is connected to the exhaust pipe 45, and brackets 47 are provided before and after the muffler 46, and are attached to the arm member 32 via the bracket 47. Further, a cover 48 is directly attached to a side portion of the muffler 46.

In this manner, the exhaust system A of the unit swing engine 21 is arranged on one side on the right side of the vehicle body,
The intake system B is arranged on the other side on the left side of the vehicle body.

Further, a water jacket 49 is formed in the cylinder head 28 of the cylinder 25, and cools the cylinder head 28 by circulating cooling water to a radiator 80 arranged on the right side of the cylinder block 27. It has become. On the other hand, a fin 27a is integrally formed around the cylinder block 27, and a shroud 50 is provided so as to surround the fin 27a so that the cylinder block 27 is forcibly air-cooled.

The unit swing engine 21 is provided with an exhaust gas purification device 51, and a control unit 52 for controlling the supply of secondary air of the exhaust gas purification device 51 is disposed on the crankcase 24 of the unit swing engine 21. . The control unit 52 includes a reed valve portion 53, an air cut valve portion 54, and a diaphragm portion 55. The reed valve portion 53 has a reed valve 56, and the air cut valve portion 54 has an air cut valve 57 as a control valve according to the present invention. However, the diaphragm 58 has a built-in diaphragm 58. The valve shaft 57a of the air cut valve 57 is arranged coaxially with the pivot shaft 19 that supports the unit swing engine 21. The valve shaft 57a is provided with a diaphragm 58, and the air cut valve 57 is always opened by a spring 59. Has been energized.

Therefore, although the control unit 52 moves up and down integrally with the unit swing engine 21 in the vertical direction, the axial direction of the air cut valve 57 is
Is set in parallel with the pivot shaft 19 of the above, even if the unit swing engine 21 moves up and down, the air cut valve 57 does not flutter and does not adversely affect the supply of the secondary air. .

A secondary air supply pipe 60 for supplying secondary air
Is connected to the exhaust system via the control unit 52 from the intake system. The part of the secondary air supply pipe 60 that supplies the secondary air from the control unit 52 to the exhaust system is composed of a first iron pipe 61 and a second iron pipe 62, which are deteriorated by heat to deteriorate durability. There is no such thing. The first iron pipe 61 is the unit swing engine 2
The first iron pipe 61 is connected to a second iron pipe 62 via a gasket 63 and a clamp 64. The first iron pipe 61 is connected to an exhaust passage 44 formed in the cylinder block 28 of the first cylinder 25. And second iron pipe 6
2 extends rearward along the exhaust pipe 45, and the iron pipe 62 extends upward along the side surface of the crankcase 26 and is connected to a reed valve portion 53 of the control unit 52.

The second iron pipe 6 of the secondary air supply pipe 60
2 is attached to the exhaust pipe 45 with a stopper 65, and the front side of the first iron pipe 61 and the second iron pipe 62 is disposed along the exhaust pipe 45, but the control unit 52 of the secondary air supply pipe 60 The portion on the exhaust system side may extend from the side of the crankcase 26 downward to the front side and may be connected to the exhaust passage 44.

The portion of the secondary air supply pipe 60 on the intake system side from the control unit 52 is constituted by a resin hose 66, and this hose 66 is connected to the air cut valve portion 54 of the control unit 52. The secondary air purified by the air cleaner 43 can be introduced into the exhaust system. Although the hose 66 is connected to the air cleaner 43 connected to the vaporizer 41 via the duct 42, a dedicated air cleaner for introducing secondary air may be provided. Also in this case, the dedicated air cleaner is arranged on the intake system side.

The control unit 52 includes brackets 67 and 68
The hose 69 is connected to the diaphragm 55 of the control unit 52 via the hose 69.
Are connected to hoses 71 and 72 via a joint 70. The hose 71 is connected to the vaporizer 41, and the hose 72 is connected to a fuel negative pressure cock (not shown). Thus, the opening and closing of the air cut valve 57, that is, the supply amount of the secondary air is controlled according to the operation state.

The air cut valve 57 of the control unit 52 is opened by a spring 59 and the air cleaner 43 is opened.
Can be supplied via a hose 66, and the secondary air is supplied to the exhaust passage 44 by a first iron pipe 61 and a second iron pipe 62. As described above, the secondary air supply pipe 60 is piped from the intake system side to the exhaust system side via the control unit 52, and the exhaust system A of the unit swing engine 21 is disposed on one side on the right side of the vehicle body, and the intake system B is disposed on the other side on the left side of the vehicle body, and a secondary air supply pipe 60 that supplies secondary air to the exhaust system A is piped from the intake system B side to the exhaust system A side along the unit swing engine 21. Therefore, the piping of the exhaust gas purification device 51 does not interfere with other mounted components. Also, the secondary air supply pipe 60
Is not affected by the heat of the exhaust system A upstream of the control unit 52. Accordingly, there is no change in the density of the secondary air, and a required amount of secondary air controlled by the control unit 52 is supplied.

When the unit swing engine 21 is operated, the reed valve 56 is opened by the exhaust arterial pressure generated in the exhaust passage 44, and the clean air in the air cleaner 43 flows through the secondary air supply pipe 60 to the exhaust passage 44. Will be introduced. Therefore, in the exhaust system B, the unburned gas including the secondary air is reburned. The oxidation reaction of the exhaust gas is promoted by the catalyst of the muffler 46, and the exhaust gas is further purified.

Further, the negative pressure generated by returning the throttle valve of the carburetor 41 (not shown) at the time of sudden deceleration,
Since the diaphragm 58 is pulled against the spring 59, the air cut valve 57 closes. This prevents occurrence of afterburn. The reed valve 56
Prevents exhaust gas from flowing back to the intake system.

[0031]

As described above, according to the small motorcycle of the present invention, the control unit for controlling the supply of the secondary air is mounted on the unit swing engine, and the valve shaft of the control valve is coaxial with the pivot shaft. Since they are set in parallel, even if the unit swing engine moves up and down, there is no fluttering of the control valve and there is no adverse effect on the supply of secondary air.

[Brief description of the drawings]

FIG. 1 is a side view of a scooter type motorcycle.

FIG. 2 is a plan view of a scooter-type motorcycle.

FIG. 3 is a plan view showing a suspension of a unit swing engine and an arrangement of a control unit.

FIG. 4 is a side view of the unit swing engine.

FIG. 5 is a sectional view of a cylinder portion of the unit swing engine.

FIG. 6 is an exploded view showing a connection portion of a secondary air supply pipe.

FIG. 7 is a sectional view of a control unit.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 19 Pivot shaft 21 Unit swing engine 43 Air cleaner 51 Exhaust purification device 52 Control unit 60 Secondary air supply pipe 53 Reed valve part 54 Air cut valve part 55 Diaphragm part

Claims (1)

(57) [Claims] 1. A small motorcycle having an exhaust purification device that supports a unit swing engine on a body frame so as to be able to move up and down around a pivot shaft and supplies secondary air to an exhaust system of the unit swing engine. A small motorcycle characterized in that a control unit having a control valve for controlling the supply of secondary air is mounted on a unit swing engine, and a valve axis of the control valve is set to be parallel to the pivot axis in a coaxial direction.