JPH108949A - Secondary air supplying device for motorcycle - Google Patents

Abstract

PROBLEM TO BE SOLVED: To shorten a secondary air passage to facilitate manufacturing a cylinder head, by forming a secondary air inlet chamber on a cylinder to provide a lead valve, and connecting the front side of the lead valve to an air cleaner via the secondary air supplying tube, when an exhaust passage is opened to the cylinder head to connect an exhaust pipe. SOLUTION: A lead valve 24 is inserted into the front end opening of a secondary air inlet chamber 23 integrally formed on the front wall of a cylinder block 1, to connect a secondary air supplying pipe 27 to the front wall of a valve cover 25. The secondary air inlet chamber 23 is communicated with a secondary air passage 31 opened into an exhaust passage 5 formed on the front wall of a cylinder head 2 via an air hole 28. In operation, secondary air, supplied from an air cleaner 40 to the secondary air supplying pipe 27, expands respective leads 33 to be supplied to the respective secondary air inlet chambers 23, from the inside of the valve cover 25, supplied, also to a secondary air passage 31 and the exhaust passage 5 from the air hole 28.

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.
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 protruding 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, there is provided a motorcycle in which an exhaust passage is opened at a front surface of a cylinder head and an exhaust pipe is connected to the front of the cylinder. A secondary air inlet chamber is formed in the wall, and a reed valve is provided to allow air to flow only from the front to the secondary air inlet chamber. A front wall of the cylinder head communicates with the secondary air inlet chamber and an exhaust passage. , And a front side of the reed valve is connected to an air cleaner via a secondary air supply pipe.

The invention according to claim 2 is characterized in that an air cleaner is arranged 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.

[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, and merges 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 left and right in the rear space X2 of the exhaust pipe 9, extends rearward on the side of the cylinder block 1, and is disposed at the rear of the air cleaner 40 via the on-off valve 42. 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 the inside of 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, according to the present invention, in a motorcycle in which an exhaust passage is opened to the front of a cylinder head and an exhaust pipe is connected, a secondary air inlet chamber is formed in a front wall of a cylinder. A reed valve that allows air to flow only from the front into the secondary air inlet chamber, and forms a secondary air passage on the front wall of the cylinder head that communicates with the secondary air inlet chamber and that leads to the exhaust passage. Is connected to the air cleaner via the secondary air supply pipe, so that there are 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) The space between the front wall of the cylinder and the exhaust pipe in front of the cylinder can be effectively used for arranging the secondary air supply pipe.

(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

Claims (2)

[Claims] 1. A motorcycle in which an exhaust passage is opened in front of a cylinder head and an exhaust pipe is connected to the cylinder, a secondary air inlet chamber is formed in a front wall of the cylinder, and a secondary air inlet chamber is formed from the front. A reed valve that allows only air flow is provided, and a secondary air passage communicating with the secondary air inlet chamber and leading to the exhaust passage is formed in the front wall of the cylinder head. A secondary air supply device for a motorcycle, wherein the secondary air supply device is connected to an air cleaner via a motor. 2. A secondary air supply device for a motorcycle, comprising: an air cleaner disposed above a cylinder head cover coupled to an upper surface of a cylinder head; and a secondary air supply pipe connected to the air cleaner.