JPH11311121A - Secondary air supply device for scooter type vehicle - Google Patents

Abstract

(57) [Summary] (with correction) [PROBLEMS] To provide a secondary air supply device for a scooter type motorcycle that has a small number of parts, is easy to assemble, and can be configured at low cost. SOLUTION: A unit swing engine, which integrally holds an engine unit and a power transmission unit 17B, is swingably supported, and a unit swing engine is provided in an exhaust path for leading out exhaust of the engine.
A secondary air supply device configured to supply secondary air via a secondary air supply path, wherein the secondary air supply path includes a connecting pipe 31 for introducing outside air, and a valve unit connected to the connecting pipe 31. 32, and an air supply pipe 34 connecting the valve unit 32 and the exhaust path.
The valve unit 1 has an L-shaped bent shape and an upstream end connected to the bottom of the air cleaner 21.
Reference numeral 2 denotes an open / close valve that opens and closes the secondary air supply path in accordance with the negative pressure in the vaporizer 19 and a reed valve that prevents backflow of outside air in the secondary air supply path in a single housing. It is made.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a secondary air supply device provided for purifying exhaust gas in a scooter type vehicle.

[0002]

2. Description of the Related Art At present, in a scooter type vehicle using a so-called unit swing engine in which an engine portion and a power transmission portion for transmitting the driving force to a rear wheel are integrally held, purification of exhaust gas is performed. In order to achieve this, a secondary air supply device for supplying secondary air to the exhaust path of the engine unit is provided, and the secondary air supplied from this device enhances the combustion and purification of the catalyst provided in the exhaust path. Are generally known.

FIG. 12 and FIG. 13 are views showing a secondary air supply device of a scooter type motorcycle conventionally used. In each figure, the unit swing engine 50
Has an outer shell formed by an engine case 51 comprising left and right case portions 52 and 53. Above the engine case 51, a carburetor 53 and an engine-side air cleaner 54 for supplying air thereto are provided. ing.
Also, on the right side of the unit swing engine 50,
An air cleaner 55 for supplying secondary air (hereinafter referred to as a secondary air cleaner) separate from the engine-side air cleaner 54 is provided. This secondary air cleaner 5
The outlet 5 is connected to an exhaust path 58 of the unit swing engine 50 via a pipe 56a of a secondary air supply path 56 and the like. In addition, the secondary air supply path 56 is provided with an opening / closing valve device 59 for communicating and shutting off the path 56, a reed valve 60 for preventing backflow of air in the path 56, and the like.

The opening / closing valve device 59 is connected to a carburetor 62 through a connecting pipe 61, and a mixture gas is supplied from the carburetor 53 by the unit swing engine 50, and the inside of the carburetor 53 is reduced to a negative pressure. Then, the open / close valve 59 is opened, the secondary air supply path 56 is switched from the shut-off state to the open state, and the secondary air cleaner 5 is opened.
The air filtered at 5 is supplied to an exhaust path 58 via a secondary air supply path 56. Thereby, the exhaust path 5
Secondary combustion by a catalyst or the like is promoted in a muffler provided in 8, and clean air is discharged.

[0005]

However, in the above-mentioned prior art, components such as the secondary air cleaner 55, the opening / closing valve 59, and the reed valve 60 are arranged at remote positions. Component is pipe 56a
The secondary air supply path 56 is configured by connecting the secondary air supply path 56 with the hose 61 and the like, so that the number of parts of the secondary air supply path 56 is large, assembling becomes difficult, and the cost is increased. there were.

The present invention has been made in view of the above-mentioned problems of the prior art, and has as its object to provide a secondary air supply device for a motorcycle which has a small number of parts, is easy to assemble, and can be constructed at low cost. And

[0007]

SUMMARY OF THE INVENTION The present invention provides a unit swing engine which integrally holds an engine section for rotating a crankshaft and a power transmission section for transmitting rotation of the crankshaft to a rear wheel. The unit swing engine is supported so as to be able to swing up and down together with the rear wheel around a predetermined swing fulcrum, and the unit swing engine includes an air cleaner located above the engine unit and a carburetor located in front of the engine unit. A scooter-type vehicle having an engine-side intake path connected to the scooter-type vehicle, wherein secondary air is supplied through a secondary air supply path to an exhaust path for extracting exhaust of the unit swing engine. A secondary air supply device, wherein the secondary air supply path includes: a connecting pipe connected to an outside air introduction unit for introducing outside air; A valve unit to be connected, and an air supply pipe connecting the valve unit and the exhaust path, wherein the connection pipe has an L-shaped bent shape and has an upstream end as an outside air introduction part. The valve unit is connected to the bottom of the air cleaner. The valve unit includes an opening / closing valve for communicating and shutting off the secondary air supply path according to a negative pressure in the carburetor, and a backflow of outside air in the secondary air supply path. And a reed valve for preventing the air leakage are housed in a single housing.

In the present invention having the above configuration, the secondary air supply path is constituted by an air cleaner, an outside air introduction pipe, a connection pipe, and a valve unit inserted between both pipes. The air cleaner uses an air cleaner provided for supplying air to the carburetor, and does not use a dedicated air cleaner for supplying secondary air. In addition, the main component of the air supply path from the air cleaner to the exhaust path is only the valve unit, and since the open / close valve and the reed valve are provided integrally in this valve unit, the arrangement of components and piping And the like can be performed extremely easily, and assembling work can be reduced as compared with the related art, and the manufacturing cost can be significantly reduced.

The valve unit includes a diaphragm that defines a control room by defining a space in a housing in an airtight manner, a control pipe that communicates the control room with a carburetor, and one end fixed to the diaphragm. A valve stem, and an open / close valve fixed to the other end of the valve stem for communicating and shutting off a secondary air supply path as the valve stem advances and retreats. When the valve stem is bent and retracts from the steady position, the on-off valve is opened, and
The next air supply path is in a communicating state. Furthermore, it is also conceivable to arrange the outside air introduction pipe so as to be superposed behind the vaporizer in a front view.

[0010]

Embodiments of the present invention will be described below in detail with reference to the drawings. FIG. 1 is an external side view showing an overall configuration of a scooter type motorcycle according to an embodiment of the present invention, FIG. 2 is a rear view of the motorcycle shown in FIG. 1, and FIG. 3 is a unit swing engine shown in FIG. FIG. 4 is a right side view showing the secondary air supply device according to the first embodiment of the present invention, FIG. 5 is a front view of the one shown in FIG. 4, and FIG. FIGS. 7 to 10 are plan views showing the internal structure of the air cleaner shown, FIGS. 7 to 10 are views showing a valve unit in a secondary air supply device, and FIG. 11 is a front view showing a second embodiment of the present invention.

As shown in FIG. 1, a motorcycle 1 in this embodiment is a large two-seater scooter equipped with a four-stroke DOHC engine, and has a leg shield 2 and a screen 3 projecting left and right. A handle 6 is held by the portion 4, and a front wheel 8 is rotatably supported by a front fork 7 connected below the handle 6. Further, a double seat 10 having a backrest 9 and the like is held behind the front part 4 of the vehicle body.
The floor portion 14 is formed by a pair of left and right plate-shaped footrests 11 and 12 on which the occupant on the seat 10 can place both feet, and a protruding portion 13 provided between the footrests 11 and 12 and rising upward. Is formed. Note that a trunk room R for storing a helmet and the like is formed below the seat 10.

A rear cover 15 is provided behind the floor portion 14 to cover a rear portion of the vehicle body. Below the rear cover 15, a rear wheel 16 is supported by a unit swing engine 17 so as to be vertically swingable. ing. The unit swing engine 17 includes a pivot (a swing fulcrum) 17a.
And a cushion unit (not shown) is connected to the frame via a link mechanism or the like.
And can swing up and down.

The unit swing engine 17
A crankcase 17A accommodating a crankshaft (not shown), a transmission case 17B integrally formed behind the crankcase 17A, and a cylinder 17C protruding from the front end of the crankcase 17A. And the cylinder shell 17D form an outer shell. Further, a power transmission mechanism for transmitting the rotational force of the crankshaft to the rear wheel 16 is built in the transmission case 17B. A cylinder head cover 17E closes the front end of the cylinder head 17D.

A carburetor 19 is connected to a front end of the cylinder head 17D via a carburetor outlet tube 18. The carburetor 19 is arranged in a space in front of the cylinder head 17D, and is connected to a fuel tank (not shown). On the other hand, an outlet 21a formed in the front has an air cleaner via a carburetor inlet tube 20. 21 are connected. The outer shell of the air cleaner 21 is constituted by an air cleaner case 22. This air cleaner case 22
Is a rear portion 23 having a rectangular shape in a plan view that is wide in the vehicle left-right direction (width direction), and side portions 24 communicating with the rear portion 23.
In the inside of the rear portion 23,
The cleaner element 25 is fitted and fixed. The rear portion 25 of the air cleaner case 22 is
The side portion 24 is fixed to the upper surface of the cylinder 17C, and is located on the side of the carburetor 19, and protrudes forward of the cylinder head 17D.

The carburetor inlet tube 2 connected to the side portion 24 of the air cleaner case 22
Reference numeral 0 protrudes rightward from the right side surface of the side portion 24 and is bent in a substantially L shape so as to protrude rearward. The rear end of the inlet tube 20 is provided with a lid 23a in the vaporizer 19 so as to be detachable, and a cap 25 is detachably attached to the lid 23a. Also, on the front surface of the cap 25,
An air cleaner inlet tube 26 opening forward is attached, from which external air is introduced into the air cleaner 23. An exhaust pipe 27 as an exhaust path is connected to the cylinder head 17D, and a muffler 28 disposed on the right side of the unit swing engine 17 is connected to the exhaust pipe 27.
An exhaust path 29 is formed by the exhaust pipe 27 and the muffler 28. The muffler 28 contains a catalyst for performing secondary combustion to purify exhaust gas.

On the other hand, a secondary air supply device for supplying secondary air is connected to the exhaust path 29 to promote secondary combustion performed by the muffler 28 and the like. The secondary air supply device includes an air cleaner 21, a connecting pipe 31 connected to the air cleaner 21, a valve unit 32 connected to the connecting pipe 31, and a hose unit 33 connected to the valve unit 32. Air supply pipe 34
The air supply pipe 34 is connected near the upstream end of the exhaust pipe 27. And the connecting pipe 31
Is bent in an L-shape, and its upper end is connected to the bottom of the rear portion 23 of the air cleaner 21 and its side end is connected to the valve unit 32, respectively. The air supply pipe 34 is connected to the hose 3 connected to the valve unit 32.
After projecting obliquely downward from 3 and forward, it bends to the left and passes in front of the cylinder head cover 17E,
It is bent backward and connected near the upstream end of the exhaust pipe 27. The secondary air supply path is constituted by the above 31 to 34.

The valve unit 32 is constructed as follows. That is, the valve unit 3
As shown in FIGS. 7 to 10, a main body 33 having a cylindrical shape with a bottom, an inflow pipe 35 fitted and fixed to an opening 33 a of the main body 33, and a peripheral wall of the main body 33 are formed. An outflow pipe 36 fitted and fixed in the through hole 33 b
A cap 37 for covering the outside of an insertion hole 33c formed at the center of the bottom of the control tube 3;
8 constitutes a housing forming the outer shell. The inflow pipe 35 is connected to the bottom of the air cleaner 19 via the connection pipe 31, the outflow pipe 36 is connected to the air supply pipe 34 via a hose 33, and the control pipe 38 is connected to the vaporizer 19. I have.

A diaphragm 39 made of an elastic thin film such as rubber is held in the opening of the cap 37, thereby forming an airtight control chamber S in the housing. At the center of the diaphragm 39, a valve stem 40 to be inserted into the insertion hole 33c is protruded, and the valve stem 40 has a disc-shaped valve body capable of closing the inner opening of the inflow pipe 35. 41 is fixed. Further, a spring 42 is inserted through the valve stem 40 and the valve stem 4
0 is inserted in a compressed state between a dish-shaped spring seat 43 fixed to 0 and a convex spring receiver 33d protruding from the center of the inner surface of the main body 33. The valve 42 is compressed by the compression force of the spring 42. The body 41 is always in pressure contact with the opening 35a on the downstream side of the inflow pipe 35 to keep the opening 35a closed. Further, a reed valve 44 is held inside the outflow pipe 35 to enable the gas to flow out from the main body 33 to the air supply pipe 34 side, and to allow the main body 33 to flow out from the air supply pipe 34 side. The air can be prevented from flowing into the air.

In the present invention constructed as described above, the air introduced from the inlet tube 26 of the air cleaner 21 flows into the rear part 23, and after the dust and the like are removed by the cleaner element 25, the supply side part is removed. 24 and the carburetor 1 via the carburetor inlet tube 18.
9. Here, the carburetor 19 mixes the fuel and air supplied from a fuel tank (not shown), and mixes the resulting mixture with the cylinder head 17D of the unit swing engine 17.
The driving force is supplied to the inside to drive the engine unit 17A, and the driving force is transmitted to the rear wheel 16 by the power transmission mechanism 17B and converted into rotation of the rear wheel 16.

On the other hand, since the connecting pipe 31 is connected to the bottom of the rear portion 23 of the air cleaner 21, the air filtered by the cleaner element 25 is connected at a predetermined timing according to the driving state of the engine. It flows into the pipe 31 and into the valve unit 32. That is, the valve unit 32 is connected to the carburetor by a ventilation pipe (not shown) connected to the control pipe 38. When the pressure in the chamber of the carburetor 19 becomes negative by driving of the engine, the valve unit 32 is connected to the valve unit 32. The formed control room S becomes a negative pressure, and the diaphragm 39 is sucked inward of the control room S (in a direction away from the outer surface of the main body 33),
The valve body 41 moves against the spring 42 together with the valve rod 40, and the valve body 41 is separated from the opening 35a of the inflow pipe 35 to be in an open state, so that the inflow pipe 35 and the outflow pipe 36 communicate with each other. As a result, the air filtered by the cleaner element 25 is supplied as secondary air to the exhaust pipe 27 via the connection pipe 31, the valve unit 32, the hose 33, and the air supply pipe 34 constituting the secondary air supply path. You. Thereby, the secondary combustion in the muffler connected in the exhaust pipe 27 is promoted,
The purification action of the exhaust gas is improved.

When the pressure in the carburetor 19 increases due to the driving state of the engine unit 17A, the pressure in the control chamber S also increases. Accordingly, the diaphragm 39 is moved to the bottom of the main body 33 by the urging force of the spring 42 and the like. The valve body 41 returns to the steady position in contact with the outer surface, and the valve body 41 is
And closes it. As a result, communication between the inflow pipe 35 and the outflow pipe 36 is cut off, and the flow of air from the air cleaner 21 into the valve unit 32 is cut off.

As described above, in this embodiment,
Since the air cleaner for supplying the secondary air and the air cleaner for supplying the air to the carburetor 19 are also used, the arrangement of the component parts is smaller than that of the conventional air cleaner. In addition, piping and the like can be performed extremely easily, the assembling work is reduced, and the size and cost of the device can be reduced.

In the first embodiment, as shown in FIG. 5, the position covered by the cylinder head 17D when viewed from the front, that is, the cylinder head 1
Although it is superposed behind 7D, the valve unit 32 is housed inside the left and right width of the unit swing engine, and the length of the air supply pipe 34 is shortened as much as possible to reduce costs. The valve unit 32 may be arranged at substantially the same position as the left side wall of the unit swing engine as in the second embodiment of the present invention shown in FIG. . However, in this case, it is necessary to extend the length of the air supply pipe 34 in the left-right direction. In FIG. 11, the present invention is the same as in the first embodiment.

[0024]

As described above, according to the present invention, the secondary air supply path is constituted by the air cleaner, the connecting pipe, the air supply pipe, and the valve unit inserted between the two pipes. In addition to using the air cleaner for the vaporizer provided to supply air to the vessel, the valve unit communicates with the secondary air supply path,
Since the control valve and the reed valve that shut off are unitized to form one component, a dedicated air cleaner for supplying secondary air is provided, and the control valve and the reed valve are individually arranged at different locations. Compared with the conventional method, the number of parts can be greatly reduced, the arrangement of components, piping, etc. can be simplified, assembling work can be simplified, and manufacturing costs can be significantly reduced. Becomes possible.

[Brief description of the drawings]

FIG. 1 is an external side view showing an overall configuration of a scooter type motorcycle according to an embodiment of the present invention.

FIG. 2 is a rear view of the motorcycle shown in FIG.

FIG. 3 is a left side view showing the unit swing engine shown in FIG. 1 and its peripheral configuration.

FIG. 4 is a right side view showing the secondary air supply device according to the first embodiment of the present invention.

FIG. 5 is a front view of what is shown in FIG.

FIG. 6 is a plan view showing the internal structure of the air cleaner shown in FIG.

FIG. 7 is a side view of a valve unit in the secondary air supply device in the embodiment shown in FIG.

FIG. 8 is a front view of what is shown in FIG.

FIG. 9 is a sectional view taken along line AA of FIG.

FIG. 10 is a sectional view taken along the line BB of FIG.

FIG. 11 is a front view showing a second embodiment of the present invention.

FIG. 12 is a side view showing a unit swing engine of a conventional scooter type motorcycle and its peripheral structure.

FIG. 13 is a front view of what is shown in FIG.

[Explanation of symbols]

 Reference Signs List 16 rear wheel 17 unit swing engine 17a swinging fulcrum 17A engine unit 17B power transmission unit 18 carburetor outlet tube 19 carburetor 20 carburetor inlet tube 23 air cleaner 27 exhaust pipe (exhaust path) 31 connecting pipe 32 valve unit 32a hose 33 Main unit 34 Air supply pipe 41 Valve body 44 Reed valve

Claims (3)

[Claims] 1. A unit swing engine having an engine unit for rotating a crankshaft and a power transmission unit for transmitting the rotation of the crankshaft to a rear wheel integrally formed around a predetermined swing fulcrum. The unit swing engine is connected to an engine-side intake path including an air cleaner located above the engine section and a carburetor located in front of the engine section. A secondary air supply device for a scooter type vehicle, wherein secondary air is supplied to the scooter type vehicle via a secondary air supply path to an exhaust path for leading the exhaust of the unit swing engine. The secondary air supply path includes a connecting pipe connected to an outside air introduction unit for introducing outside air, and a valve unit connected to the connecting pipe. And an air supply pipe connecting the valve unit and the exhaust path. The connection pipe has an L-shaped bent shape and has an upstream end as a bottom portion of the air cleaner as an outside air introduction portion. The valve unit is connected to the second valve according to the negative pressure in the vaporizer.
An open / close valve for communicating and shutting off the next air supply path;
A secondary air supply device for a scooter type vehicle, wherein a reed valve for preventing backflow of outside air in a secondary air supply path is housed in a single housing. 2. A valve unit, comprising: a diaphragm that defines a control chamber by defining a space inside a housing in an airtight manner; a control pipe that connects the control chamber to a carburetor; and one end fixed to the diaphragm. A valve stem, and an opening / closing valve fixed to the other end of the valve stem to open and close a secondary air supply path as the valve stem advances and retreats. The secondary air supply device for a scooter type vehicle according to claim 1, wherein the on-off valve is opened when the valve stem is retracted from the steady position, and the secondary air supply path is in a communicating state. 3. The outside air introduction pipe is arranged so as to be superposed behind the vaporizer in a front view.
Or a secondary air supply device for a scooter-type vehicle according to 2.