JPS632005B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides an internal combustion engine for a motorcycle that supplies secondary air to the exhaust system of an internal combustion engine for running the motorcycle and promotes the combustion of unburned harmful components in the exhaust gas flowing therethrough. This relates to an engine exhaust purification device.

Generally, the exhaust gas purification device for motorcycles connects a secondary air supply system to the exhaust system, and a reed valve device is inserted in the middle of this secondary air supply system to respond to the exhaust pulsating pressure generated within the exhaust system. A reed valve device is already known in which the reed valve device is opened to supply secondary air for purifying the exhaust gas to the exhaust system (see Japanese Patent Laid-Open No. 1983-65215). By the way, in such an exhaust gas purification device, the passage that communicates the reed valve device of the secondary air supply system with the exhaust system, that is, the passage downstream of the reed valve device, is used to introduce secondary air into the exhaust system. In addition to being a passageway for the exhaust system, it also plays the role of transmitting the exhaust pulsating pressure in the exhaust system to the reed valve device and opening it, so that high-temperature exhaust gas is released instantly during the opening and closing operation of the reed valve device. The water flows back into the downstream passage and reaches the reed valve device, heating the downstream passage and the reed valve device, so it is necessary to take measures to effectively cool them.

Furthermore, in a motorcycle, since the internal combustion engine is exposed to the outside, the exhaust purification device is also exposed to the outside and attached to the internal combustion engine. It is desirable to place the device close to other equipment to prevent it from being damaged from the outside, and to avoid interfering with the installation and maintenance of existing equipment.

In view of the above circumstances, the present invention makes it possible to effectively cool the secondary air supply system, especially the supply system downstream of the reed valve, by using the running wind of a motorcycle, and also prevents the entire exhaust purification system from being damaged from the outside. It is an object of the present invention to provide an exhaust gas purification device for an internal combustion engine for a motorcycle, which has a simple structure and can be installed so as not to be affected by the heat.

In order to achieve the above object, the present invention
An internal combustion engine mounted on the body frame is housed in a space surrounded by a fuel tank and a seat supported on the upper part of the body frame, and front and rear wheels supported on the front and rear parts of the body frame. In this motorcycle, an exhaust port connected to an exhaust system is opened at the front of the internal combustion engine, and an exhaust pulsation pressure-responsive reed valve device is connected to the top surface of the head cover of the internal combustion engine, and the flow rate of the reed valve device is A secondary air introduction pipe that communicates with the atmosphere is connected to the inlet, and a secondary air distribution passage that is integrally formed with the head cover along the front surface thereof and communicates with the exhaust port is connected to the outlet of the device. It is characterized by connecting.

Hereinafter, one embodiment of the present invention will be described with reference to the drawings. In FIG. 1, a fuel tank T and a seat S are supported on the upper part of a body frame F of a motorcycle V, and front and rear wheels Wf,
Wr is supported, and in the space C surrounded by them, the rear wheel
It is equipped with a Wr internal combustion engine E for driving.

In Fig. 2, the cylinder head 2 of the engine body 1
An intake port 5 communicating with the combustion chamber 4 on the piston 3 is formed in the rear half thereof, and an exhaust port 6 communicating with the combustion chamber 4 in the front half thereof is formed in a uniflow type. The exhaust port 6 opens at the rear surface of the engine body 1, and the exhaust port 6 opens at the front surface of the engine body 1. An intake system such as a carburetor 7 and an air cleaner 8 disposed at the rear of the engine body 1 is connected to the intake port 5, and an exhaust system such as an exhaust pipe 9 and a muffler 10 is connected to the exhaust port 6. An exhaust gas purifying catalytic converter 11 is interposed in the middle of the exhaust gas. In addition, the cylinder head 2 has intake and exhaust ports 5 and 6 as usual.
Intake and exhaust valves 1 that open and close the opening end on the combustion chamber 4 side.
2 and 13 are provided, which are opened and closed by the cooperation of a valve spring 14 and a valve operating mechanism 15.

A head cover 17 is attached to the upper part of the cylinder head 2 with a packing material 16 interposed therebetween. An exhaust pulsation pressure responsive reed valve device L is integrally connected to the upper surface of the head cover 17.

The valve box 18 of the reed valve device L is attached to the head cover 1.
It is fixed onto a mounting surface 19 formed at the left and right center portions of the upper surface of 7 via a packing 20. Inside the valve case 18, a pair of left and right reed valves 21 are arranged side by side, and above these reed valves 21 there are formed left and right upstream chambers 22 corresponding to them, and below each reed valve 21 there are formed a pair of left and right upstream chambers 22 corresponding to the reed valves 21. Corresponding left and right downstream chambers 23 are formed. The valve seat body 24 of each reed valve 21 is
It is formed in a rectangular shape and is supported by the valve case 18 via a heat-resistant elastic packing material 25 having a U-shaped cross section, and each valve seat body 24 is provided with a valve hole 26 as shown in FIGS. 4 and 5. Each upstream chamber 22 and each downstream chamber 23 communicate with each other via each valve hole 26 . A reed seat surface 27 is provided on the lower surface of each valve seat body 24 facing the downstream chamber 23.
A reed 28 that can open and close each of the valve holes 26 is superimposed on this reed seat surface 27, and a reed stopper 29 that limits the degree of opening of this reed 28 is superimposed thereon. The base end of the lead stopper 29 is fixed to the valve seat body 24 with a set screw 30.

An inlet port 31 communicating with the left and right upstream chambers 22 is opened in the valve box 18 . The free end edges 32' of the partition wall 32 that partition the left and right upstream chambers 22 are tapered and face each other with a gap in the center of the inflow port 31. 32′ and
A branch passage 34 ₁ that connects the inflow port 31 to the left and right upstream chambers 22 through the wall surface of the valve case 18;
34 ₂ is formed. The secondary air from the inlet 31 is divided into approximately equal parts by the branch passages 34 ₁ and 34 ₂ and distributed to the left and right upstream chambers 22 . A secondary air introduction pipe 35 is connected to the inflow port 31 via a connecting pipe 40 provided with an orifice 50,
This secondary air introduction pipe 35 is communicated with the air cleaning chamber of the air cleaner 8 via an air control valve 36 in the middle thereof. The air control valve 36 is conventionally known and is normally closed, but is opened in response to negative intake pressure in the intake system when the internal combustion engine E is operating.

Two secondary air distribution passages 37 are integrally formed along the front surface of the head cover 17, and these passages 37 each extend toward the exhaust port 6. Each secondary air distribution passage 3
The upper end of 7 is communicated with the outlet 33 of the downstream chamber 23,
Its lower end is open to the lower surface of the head cover 17. Further, a passage 38 is formed in the cylinder head 2 and communicates with the exhaust port 6.
8 is connected to the secondary air distribution passage 37 via a connection joint 39, which will be described later. The secondary air distribution passage 37 and the passage 38 are formed to have approximately the same diameter.
Therefore, the suction force generated by the exhaust pulsating pressure generated in the exhaust port 6 opens the reed valve 21 and directs the secondary air in the upstream chamber 22 through the secondary air distribution passage 37 and passage 38 to the exhaust port. It can be introduced within 6.

The connection joint 39 is formed into a rivet shape from a material with low thermal conductivity such as phenolic resin, and the inner wall of the hollow part is covered with a heat-resistant metal foil or plate 41.
It is lined with. Connection joint 3
The large diameter head 42 of No. 9 is located in a recess 43 formed on the upper surface of the cylinder head 2 and communicating with the passage 38.
It is fitted in an airtight manner via an O-ring 44, and its small diameter pin portion 45 projects upward from the upper surface of the cylinder head 2. Note that the large diameter head 42 is located in the recess 4.
3 may be press-fitted or fixed in an airtight manner by other means. On the other hand, the head cover 17 is formed with an insertion hole 46 that communicates with the secondary air distribution passage 37 in correspondence with the small diameter pin portion 45 of the connection joint 39. By fitting the insertion hole 46 into the small diameter pin portion 45 of the connection joint 39 via an O-ring 47, the secondary air distribution passage 37 is airtightly connected to the passage 38 via the connection joint 39. The connecting joint 39 also functions to position the head cover 17 with respect to the cylinder head 2.

Secondary air distribution passage 3 of the head cover 17
A gap 48 is formed on the back side of the secondary air distribution passage 37 so as to surround the passage 37, and cooling fins 49 are integrally protruded from the front part of the outer peripheral wall of the secondary air distribution passage 37. The secondary air distribution passage 37 is effectively cooled.

Next, the operation of one embodiment of the present invention configured as described above will be explained.

When the internal combustion engine is operated, exhaust pulsating pressure is generated in the exhaust port 6, and this pulsating pressure passes through the passage 38, the connecting joint 39, and the secondary air distribution passage 37, and reaches the pair of reed valves 21, thereby discharging them. The valve is opened, and when the air control valve 39 is opened by the operation of the engine E, a part of the clean air in the air cleaner 8 is passed through the secondary air introduction pipe 35 to the upstream chamber 2 in the valve box 18.
2 and further flows into the downstream chamber 22 through the valve hole 26 of each reed valve 21 and from there into each exhaust port 5 through each secondary air distribution passage 37 and passage 38.

An orifice 50 is provided in the connecting pipe 40 that connects the inlet 31 of the valve case 18 and the secondary air introduction pipe 35.
is interposed, the air flow rate is adjusted upstream of the reed valve device L, and the secondary air distribution passage 3
7 and the passage 38 are formed to have approximately the same diameter over their entire length, so on the downstream side of the reed valve device L,
A substantially constant flow of secondary air flows, minimizing the attenuation of the pulsating pressure of the exhaust gas, and ensuring that the reed valve 21 is opened. The secondary air introduced into each exhaust port 6 mixes into the exhaust gas, and HC, which is mixed in the exhaust gas at the exhaust port and the exhaust pipe 9,
Oxidizes unburned harmful components such as CO. Furthermore, the exhaust gas mixed with secondary air flows into the muffler 10, promotes the reaction of the catalytic converter 11 built therein, and after finally purifying the unburned harmful components therein, is released into the atmosphere. .

By the way, since the reed valves 21 are opened and closed by positive and negative pressures caused by exhaust gas pulsations in the corresponding exhaust ports 6, the exhaust gas in the exhaust ports 6 instantly flows back through the secondary air distribution passage 37. In such a case, the secondary air distribution passage 37 and the reed valve device L are heated by the exhaust gas heat, and the components of the reed valve device L, especially the heat-resistant ones that are sensitive to heat, are heated. Although there is a risk that the elastic packing material 25 will deteriorate and the reed valve 21 will not function properly, and the life of the reed valve device L will be shortened, the secondary air distribution passage 37 should be aligned along the front surface of the head cover 17. Moreover, by providing a gap 48 in a part of its periphery and protruding cooling fins 49, the secondary air distribution passage 37 is effectively cooled by the running wind of the motorcycle, and its temperature rise is alleviated. be done.

As described above, according to the present invention, in a motorcycle that houses an internal combustion engine in a space surrounded by a fuel tank, a seat, and front and rear wheels, an exhaust pulsation pressure-responsive reed is provided on the upper surface of the head cover of the internal combustion engine. Since the valve device is installed in series, the reed valve device does not protrude directly to the outside, preventing contact and collision between the reed valve device and other objects, and preventing the reed valve device from colliding with other objects, not only when the motorcycle is running, but also when the motorcycle falls over. The reed valve device will not be damaged.

Furthermore, since the secondary air distribution passage that communicates the reed valve device and the exhaust port is formed integrally with the head cover so as to run along the front surface of the head cover, it is effectively cooled by the running wind of the motorcycle, and the secondary air distribution passage communicates with the exhaust port. The high-temperature exhaust gas flowing back into the secondary air distribution passage is quickly and efficiently cooled, preventing the reed valve device from being excessively heated by the heat of the exhaust gas, and minimizing deterioration and damage to the components of the device due to heat. This can extend the life of the device. Moreover, since the secondary air distribution passage, which is integrated with the head cover, can connect the reed valve device on the top surface of the head cover and the exhaust port as short as possible, the exhaust pulsating pressure is transmitted to the reed valve device with little resistance and controls its opening and closing. It can always be done accurately. Furthermore, since the secondary air distribution passage is formed integrally with the head cover, there is no protruding part to the outside, thereby preventing damage and breakage, and the head cover with the reed valve device can be simply attached to the cylinder head. The reed valve device can be easily connected to the exhaust port with just one step, simplifying the piping work.
Furthermore, since the reed valve device and the secondary air distribution passage are not exposed individually but are integrated into the head cover, the appearance can be improved.

Incidentally, if the head cover is provided with a gap that surrounds at least a portion of the secondary air distribution passage as in the above embodiment, and cooling fins are provided protruding from the outer periphery of the secondary air distribution passage, the secondary air Cooling of the distribution passage becomes more effective.

[Brief explanation of the drawing]

Fig. 1 is a side view of a motorcycle equipped with the device of the present invention, Fig. 2 is a longitudinal cross-sectional side view of the internal combustion engine head, and Fig. 3
4 is a cross-sectional plan view of the reed valve device, FIG. 5 is a sectional view taken along line V--V in FIG. 4, and FIG. 6 is a sectional view taken along line 2-- in FIG. 1... Internal combustion engine body, 6... Exhaust port, 17... Head cover, 31... Inlet, 33... Outlet, 35
...Secondary air introduction pipe, 37...Secondary air distribution passage, 4
8... air gap, 49... cooling fin, C... space, E... internal combustion engine, F... body frame, L... reed valve device,
S...Seat, T...Fuel tank, Wf...Front wheel, Wr
...rear wheel.

Claims (1)

[Claims] 1. A space C surrounded by a fuel tank T and a seat S supported on the upper part of the vehicle body frame F, and front and rear wheels Wf and Wr supported at the front and rear of the vehicle body frame F. In a motorcycle, a head cover 17 of the internal combustion engine E is configured to house an internal combustion engine E mounted on the body frame F, and has an exhaust port 6 opened to the front surface of the internal combustion engine E to which an exhaust system is connected. An exhaust pulsating pressure responsive reed valve device L is connected to the upper surface, and a secondary air introduction pipe 35 communicating with the atmosphere is connected to the inlet port 31 of the reed valve device L.
Further, at the outlet 33 of the device L, a secondary air distribution passage 3 is formed integrally with the head cover 17 along the front surface thereof and communicates with the exhaust port 6.
7 is connected to an exhaust purification device for an internal combustion engine for a motorcycle. 2. In the exhaust purification device for an internal combustion engine for a motorcycle as set forth in claim 1, the head cover 17 of the internal combustion engine E is provided with a gap 48 that surrounds at least a portion of the secondary air distribution passage 37. Exhaust purification device for internal combustion engines for motorcycles. 3. In the exhaust purification device for an internal combustion engine for a motorcycle according to claim 1 or 2, cooling fins 4 are provided on the outer periphery of the secondary air distribution passage 37.
9. An exhaust purification device for an internal combustion engine for a motorcycle, comprising: