JP2868468B2 - Secondary air supply device for motorcycles - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a secondary air supply device for a motorcycle.

[0002]

2. Description of the Related Art FIG. 4 shows an example of a conventional secondary air supply device for a motorcycle, in which a cylinder head cover 13 is provided.
A secondary air inlet chamber 54 containing a reed valve 53
The upstream side (upper side) of the reed valve 53 is connected to an air cleaner 58 via a secondary air supply pipe 57 projecting upward, and the downstream side of the reed valve 53 is exhausted from the cylinder head 2 via a secondary air passage 59. It is connected to passage 5.

The secondary air passage 59 is formed integrally with the head cover 13 and extends downward. The secondary air passage 59 is formed integrally with the cylinder head 2 and extends upward.
1 and connects the two thin tube portions 60 and 61 via a packing or the like. 63 is the seam.

[0004] As a prior art document, Japanese Utility Model Publication No. 55
No. 53693.

[0005]

When the secondary air inlet chamber 54, the reed valve 53 and the secondary air supply pipe 57 connected to the secondary air inlet chamber 54 are arranged on the upper wall of the cylinder head cover 13 as shown in FIG. Space X1 above head cover 13
Therefore, even if an attempt is made to place a fuel tank or an air cleaner in the space X1, the shape or volume thereof is limited, and the degree of freedom in design is reduced.

Further, secondary air is guided from the upper wall of the cylinder head cover 13 to the exhaust port at the lower end of the cylinder head through the valve arm chamber and the cylinder head wall.
When the way becomes long, the core (pin) for punching used at the time of casting becomes slender, and the manufacturing operation is difficult. For example, the core may break. On the other hand, when a separate pipe is inserted instead of forming the elongated tubes 60 and 61 integrally, the number of parts and the number of working steps increase.

The space X2 between the front side of the cylinder block 1 and the exhaust pipe 9 is affected by heat of the exhaust pipe 9 and the like.
Not used and dead space.

[0008]

According to a first aspect of the present invention, an exhaust pipe 5 is formed by opening an exhaust passage 5 at a front surface of a cylinder head of an engine having a plurality of cylinders arranged in parallel. In the connected motorcycle, a pair of concave secondary air inlets 23 for adjacent cylinders are arranged adjacent to each other on a front wall portion of a cylinder block between adjacent cylinders via a partition wall 36, and each secondary air A reed valve 24 that allows air to flow only from the front to the secondary air inlet chamber 23 is provided in the inlet chamber 23.
And a pair of adjacent secondary air inlet chambers 23
, A common valve body 32 and a common valve cover 25 are provided, and each secondary air inlet chamber 23 is provided on the front wall of the cylinder head 2.
And a secondary air passage 31 extending to the exhaust passage 5 is formed, and the front side of the adjacent reed valve 24 is connected to the air cleaner 40 via the common secondary air supply pipe 27. .

The invention according to claim 2 is characterized in that an air cleaner is disposed above a cylinder head cover connected to an upper surface of a cylinder head, and a secondary air supply pipe is connected to the air cleaner.

With the above structure, the secondary air passage from the secondary air inlet chamber to the exhaust passage can be shortened, and the production (casting) of the cylinder head is facilitated.

In addition, a sufficient space above the cylinder head cover can be ensured, and the degree of freedom in setting the shape or volume of the air cleaner or the fuel tank increases. In addition, the space in front of the cylinder block can be used more effectively, and the operation of mounting the valve body and the valve cover can be simplified.

[0012]

1 to 3 show a motorcycle internal combustion engine to which the present invention is applied, which is a four-cylinder engine in which all cylinders are uniformly formed in a forward leaning posture. In FIG. 2 showing an enlarged longitudinal sectional view of one cylinder, a cylinder head 2 connected to an upper end of a cylinder block (cylinder) 1 is shown.
An exhaust passage 5 extending from the combustion chamber 3 to the front and upward in a curved shape, and an intake passage 6 extending from the combustion chamber 3 to the upper rear and in a substantially straight line are formed. An exhaust pipe 9 is connected to a front end opening 5b of the exhaust passage 5, an exhaust valve 7 is arranged at an exhaust port 5a opening to the combustion chamber 3, and an intake pipe 1 is connected to a rear end opening 6b of the intake passage 6.
A carburetor 11 is connected via the valve 0 and an intake valve 8 is arranged at an intake port 6 a opening to the combustion chamber 3.

The exhaust valve 7 and the intake valve 8 penetrate the cylinder head 2 into the upper valve arm chamber 12, and each of the valve arm 1
It is engaged with camshafts 17 and 18 via 5, 16. A cylinder head cover 13 is connected to an upper end of the cylinder head 2, and a spark plug 14 is attached to the cylinder head cover 13. In the cylinder block 1, a cylinder liner 20 is fitted for each cylinder, and a piston 21 is fitted in the cylinder liner 20.

A secondary air supply device which is a main part of the present invention will be described. The front wall of the cylinder block 1 is integrally formed with a concave secondary air inlet chamber 23 which is open frontward for each cylinder, and a reed valve (assembly) is provided at the front end opening of the secondary air inlet chamber 23. 24 is fitted and fixed to the cylinder block 1 by a valve cover 25. A secondary air supply pipe 27 is connected to a front wall of the valve cover 25.

The secondary air inlet chamber 23 has an air hole 28 at the upper end.
The secondary air passage 31 communicates with a secondary air passage 31 formed in the front wall of the cylinder head 2 through the cylinder head 2. The secondary air passage 31 extends upward from the lower surface position of the cylinder head, bends backward halfway, and opens into the exhaust passage 5. doing.

The reed valve 24 has a frame-shaped main body 32 having a valve hole 30, a flexible lead 33 disposed on the rear surface of the main body 32 so as to cover the valve hole 30, and an upper portion rearward. And a curving opening regulating plate 34.
Although the lead 33 is actually a thin sheet, the thickness is exaggerated in the figure.

The lower end of the lead 33 is fastened together with the opening regulating plate 34 by a screw 35. The lead 33 is reed by the pressure of the secondary air from inside the valve cover 25 (the pressure difference from the secondary air inlet chamber 23). 33 is opened rearward, and the secondary air inlet chamber 2 is opened.
3, and the secondary air flows into it.

FIG. 3 is a cross-sectional view taken along the line III-III of FIG. 2, in which the secondary air inlet chambers 23 for adjacent cylinders are arranged adjacent to each other with a partition wall 36 therebetween. 23
, A common valve body 32 and a common valve cover 25 are arranged. That is, the secondary air that has entered the common valve cover 25 from the secondary air supply pipe 27 pushes and opens the lead 33 for each cylinder to enter the secondary air inlet chamber 23. Therefore, in a four-cylinder internal combustion engine, the valve covers 25 and the secondary air supply pipes 27 for the first and second cylinders and the valve covers 25 and the secondary air supply pipes 27 for the third and fourth cylinders are arranged. ing.

FIG. 1 is a left side view of the entire internal combustion engine. The exhaust pipe 9 extends downward behind the front radiator 37 and bends rearward below the engine to merge two by two. And then to the rear of the aircraft. 38 is a crankcase and 39 is a mission case.

An air cleaner 40 is arranged in a space above the cylinder head cover 13. Each of the secondary air supply pipes 27 is bent right and left in the rear space X2 of the exhaust pipe 9 and extends rearward on the side of the cylinder block 1. Connected to

The operation will be described. The air cleaner 40 of FIG.
The secondary air supplied to the secondary air supply pipe 27 through the on-off valve 42 is sent forward and pushes each lead 33 from inside the valve cover 25 as shown in FIG. It is supplied to the chamber 23.

Since the upper end of the lead 33 is bent backward in FIG. 2, the secondary air is guided upward and the air hole 28 is formed.
Into the secondary air passage 31 of the cylinder head 2 through
It is supplied to the exhaust passage 5.

[0023]

Other Embodiments The present invention can be applied to an internal combustion engine having a plurality of cylinders other than a single cylinder or four cylinders.

[0024]

As described above, the present invention relates to a motorcycle in which a plurality of cylinders are arranged in parallel and in which the exhaust pipe 5 is opened and the exhaust pipe 9 is connected to the front surface of the cylinder head of the engine. A concave secondary air inlet 23 for an adjacent cylinder is arranged adjacent to a front wall portion of a cylinder block between the two via a partition wall 36, and each secondary air inlet chamber 23 is connected to the secondary air inlet chamber 23 from the front. A reed valve 24 for allowing only air to flow is disposed, and a common valve body 32 and a common valve cover 2 are provided for a pair of adjacent secondary air inlet chambers 23.
5, a secondary air passage 31 communicating with each secondary air inlet chamber 23 and reaching the exhaust passage 5 is formed on the front wall of the cylinder head 2, and the front side of the adjacent reed valve 24 is connected to a common secondary air passage. The connection to the air cleaner 40 via the air supply pipe 27 has the following advantages.

(1) Compared with the conventional structure in which a long secondary air passage is formed from the upper wall of the cylinder head cover to the exhaust passage through the valve arm chamber, the secondary passage from the secondary air inlet chamber to the exhaust passage is formed. The secondary air passage can be shortened, and the manufacture (casting) of the cylinder head becomes easy.

(2) Since the secondary air inlet chamber 23 is formed by forming a recess in the front end wall of the cylinder block, the space between the secondary air inlet chamber 23 and the exhaust pipe 9 in front thereof is effective for disposing the secondary air supply pipe 27. Further, a pair of secondary air inlet chambers 23 for adjacent cylinders are arranged adjacent to each other via a partition wall 36, and the valve body 32 and the valve cover 25 of the reed valve 24 for both secondary air inlet chambers are shared. The number of parts is reduced, and the space in front of the cylinder block can be used more effectively.
The work of attaching the valve body 32 and the valve cover 25 can also be simplified.

(3) The space above the cylinder head cover can be sufficiently ensured, and when it is used as a space for arranging an air cleaner or a space for arranging a fuel tank as in the second aspect of the present invention, setting the shape or volume thereof. The degree of freedom increases.

[Brief description of the drawings]

FIG. 1 is a side view of a main part of a motorcycle provided with a secondary air supply device according to the present invention.

FIG. 2 is a longitudinal sectional view (a II-II sectional view of FIG. 3) of the internal combustion engine of the motorcycle of FIG.

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

FIG. 4 is a longitudinal sectional view of a conventional example.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Cylinder block (cylinder) 2 Cylinder head 5 Exhaust passage 9 Exhaust pipe 23 Secondary air inlet chamber 24 Reed valve 27 Secondary air supply pipe 31 Secondary air passage 40 Air cleaner

Continuation of the front page (56) References JP-A-60-79115 (JP, A) JP-A-58-106119 (JP, A) JP-A-4-153522 (JP, A) JP-A-59-90715 (JP) , A) Japanese Utility Model Application Hei 4-137216 (JP, U) Japanese Utility Model Application No. 3-45400 (Japanese Utility Model Application No. 4-137216) (58) Field surveyed (Int.Cl. ⁶ , DB name) F01N 3/34

Claims (2)

(57) [Claims] 1. In a motorcycle in which an exhaust passage 5 is opened to the front of a cylinder head of an engine in which a plurality of cylinders are arranged in parallel and an exhaust pipe 9 is connected, a cylinder block front wall between adjacent cylinders is provided with: A pair of concave secondary air inlets 23 for adjacent cylinders are arranged adjacently via a partition 36;
Each secondary air inlet chamber 23 has a secondary air inlet chamber 23 from the front.
And a common valve body 32 and a common valve cover 25 for a pair of adjacent secondary air inlet chambers 23, and a front wall of the cylinder head 2 includes: Secondary air passages 31 communicating with the respective secondary air inlet chambers 23 and reaching the exhaust passage 5 are formed, respectively.
The front side of the adjacent reed valve 24 is connected to the common secondary air supply pipe 2.
A secondary air supply device for a motorcycle, wherein the secondary air supply device is connected to an air cleaner 40 via a motor 7. 2. The motorcycle according to claim 1, wherein an air cleaner is disposed above a cylinder head cover coupled to an upper surface of the cylinder head, and a secondary air supply pipe is connected to the air cleaner. Next air supply device.