JPS6215462Y2 - - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to a secondary air supply device that efficiently and appropriately supplies secondary air necessary for exhaust purification of a motorcycle equipped with an exhaust purification device.

When an exhaust purification device mainly consisting of a catalyst device is installed in the exhaust system of a motorcycle for the purpose of exhaust purification, it is necessary to supply secondary air to promote the oxidation reaction of the exhaust gas supplied to the catalyst device. Preferably, the secondary air supply must be efficient and appropriate.

Such secondary air is supplied to the exhaust system by opening and closing a reed valve using exhaust pulsation in the exhaust system, and automatically supplying the required amount to the exhaust system upstream of the catalyst device. The arrangement of the reed valve requires consideration in terms of efficiency and suitability of secondary air supply, as well as the type of engine and arrangement of the exhaust pipe.

The present invention was developed to meet the demand for such a secondary air supply system in a multi-cylinder engine with a horizontal V-type crankshaft, and its purpose is to:
A reed valve device is installed below the air cleaner located between the front and rear cylinders of the engine at the front lower part of the frame, and this is connected to the air cleaner via piping.The reed valve device is also installed at the rear of the lower part of the frame to connect the exhaust chamber and the front cylinder. An object of the present invention is to provide a secondary air supply device in which the upstream portion of the chamber of the exhaust pipe provided in the exhaust pipe and the reed valve device are connected in communication, and the secondary air supply is optimized and made efficient.

Next, a preferred embodiment of the present invention will be described in detail with reference to the accompanying drawings.

FIG. 1 is a schematic side view of a motorcycle 1, in which a front fork 4 supporting a front wheel 5 is supported in a steerable manner on a head tube 3 at the front end of a frame 2, and a handle 7 is disposed on a top bridge 6. In the embodiment, as shown in FIG. 2, the frame 2 includes a main pipe 2a extending rearward from the upper part of the head tube 3 with a slight downward inclination, a main pipe 2a extending rearward from the lower part of the head tube 3, and a middle part of the main pipe 2a. Connecting subtube 2b, subtube 2
Down tube 2c hanging down from b, down tube blower 2 extending rearward from the lower end of the down tube 2c
d, a center tube 2e that stands up from the rear end of this tube and is continuous with the rear end of the main pipe 2a; a rear stay 2 that extends rearward from the rear end of the main pipe 2a;
f down tube blower 2d rear end and rear stay 2f
It consists of substay 2g etc. that diagonally connects the rear part. The down tube 2c, the lower tube 2d, the center tube 2e, etc. are arranged in parallel on the left and right, and cross pipes 2h, 2i are installed horizontally between the lower ends of the down tubes 2c and between the rear ends of the lower tubes 2d.

A fuel tank 8 is mounted on the main pipe 2a of the frame 2, a seat 9 is attached to the rear of this, and a center tube 2e and a substay 2g are installed.
A substantially inverted triangular sub-plate 10 is connected between the lower parts of the rear fork 1 that supports the rear wheel 12.
The front end of 1 is pivotally connected, 13 in the figure is a seat cowl,
14 is a rear fender, 15 is a headlight unit, and 16 is a meter unit.

Above main pipe 2a, down tube 2
c, an engine 17 is mounted in a space surrounded by a lower part 2d and a center tube 2e. Engine 17
is a multi-cylinder engine with a V-shaped side and a horizontal crankshaft, and in this embodiment, the front cylinder 17a has two cylinders on the left and right, and the rear cylinder 17b has two cylinders on the left and right, for a total of four cylinders, and the front cylinder 17a is tilted forward. A portion thereof protrudes forward from the left and right down tubes 2c, and the rear cylinder 7b stands up and is slightly tilted rearward, forming a side V-shaped space between the cylinders 17a and 17b. The front and rear cylinders 17a and 17b each consist of a cylinder block 17d and a cylinder head 17e projecting from the crankcase 17c, and a cylinder head cover 17f, and the rear part of the crankcase 17c constitutes a transmission case.

The exhaust ports 17g of the left and right front cylinders 17a are opened downward in front of the down tube 2c, and are connected to the upstream ends of the exhaust pipes 18 whose sides are bent into an approximately L-shape. is facing the front of the down tube, and lower 2 from the bottom of the down tube.
A rear portion 18c that curves rearward following a shape continuous with d and extends rearward from the curved portion 18b is connected to the lower 2
d, and is connected to the front side of an exhaust chamber 19 disposed below the center tube 2e at the rear end portion 18d of the lower 2d. The exhaust ports 17h of the left and right rear cylinders 17b open rearward and are connected to the front ends of the exhaust pipes 20 having an L-shaped side surface.
The lower end of the chamber 19 is connected to the upper side of the chamber 19 to collect exhaust gas from the front and rear cylinders 17a and 17b into the chamber 19.

The exhaust chamber 19 is formed to have a length in the vehicle width direction, and has exhaust ports 19a and 19 on the left and right sides of the rear end.
a, to which the front ends of left and right mufflers 21 extending rearward are connected, and a catalyst 22 is connected to the front end of the muffler 2.
It's decorated.

An air cleaner 23 is disposed between the front and rear cylinders 17a and 17b, and the air cleaner 23 consists of an air cleaner case 23a, an internal air cleaner element 23b, etc.
The clean side in b is the front/rear cylinder 17
It is communicatively connected to the fuel supply device 24 of a and 17b.

Down tube 2c below the air cleaner 23
A reed valve device 25 is disposed between the lower end of the box 2d and the front end of the lower 2d.
An upstream chamber 25c is provided which communicates with an inlet 25b that introduces secondary air into the interior of the air conditioner. Close the left and right sides of the box with the left and right covers 25d, 25d,
A downstream chamber 25e and an upstream chamber 25c formed by 25d
A reed valve 26 is interposed between the left and right sides of the reed valve, and although only one side is shown in FIG. 4, the other side is constructed in the same manner.
Secondary air outlets 25f, 25f are provided in the left and right covers 25d, 25d. This reed valve 26 is made of a flexible material and allows flow only from the upstream chamber 25c to the downstream chamber 25e. The horizontal piece 27a of the mounting stay 27 having an L-shaped side surface is tied to the lower surface of the box 25a, the vertical piece 27b bent and standing up from the front end is tied to the cross pipe 2h, and the front and lower surfaces of the box 25a are attached to the stay. Cover with 27. Therefore, the stay 27 also functions as a guard plate that covers the front and lower surfaces of the reed valve device 25, and protects the reed valve device from flying stones and the like.

The upwardly protruding inlet port 25b is connected to the clean side inside the element 23b of the air cleaner 23 located above through a pipe 28. Further, secondary room air supply pipes 29, 29 are arranged inside the rear part 18c of the left and right exhaust pipes 18, 18, and the downstream ends 29a of these pipes are connected so as to open to the downstream part of the rear part 18c in front of the exhaust chamber, The upstream end 29b of the supply pipe 29 is connected to the outlet 25f of the reed valve device 25 by a joint pipe 30 made of, for example, a rubber material.

Next, to explain its function and effect in detail, exhaust gas is collected in the chamber 19 via the front and rear exhaust pipes 18 and 20, and from there is emitted through the muffler 21, but downstream of the exhaust chamber 19. is purified by the catalyst 22. By the way, due to the exhaust pulsation in the front exhaust pipe 18, the pressure in the secondary air supply pipe 29 facing the downstream side thereof becomes alternately positive and negative, and when the pressure is negative, it acts on the reed valve 26 via the pipes 29 and 30. Then, by opening this, purified air that has passed through the air cleaner 23 is sucked in from the upstream chamber 25c, and secondary air is introduced into the exhaust system from the downstream part of the exhaust pipe 18.
9 and promotes the subsequent oxidation reaction of the catalyst 22.

By the way, the reed valve device is located below the air cleaner, in the front lower part of the frame, and below the front cylinder of the engine, so it is advantageous in terms of space utilization, and the installation support is also provided by the cross pipe between the down tubes that is interposed between them. The stay can also be used as a guard plate to protect the reed valve device.

In particular, the space under the front cylinder with the V-shaped side and forward-tilting front cylinder can be used effectively.
The reed valve device is located approximately midway between the upper air cleaner and the exhaust pipe opening of the supply pipe, so it is possible to ensure the supply by using rational piping and reliable exhaust pulsation, and the reed valve opening/closing response. It can also be expected to have accurate movement, and also suppresses the occurrence of afterburn that would occur if it is installed in the upstream part to supply secondary air to the downstream part of the exhaust pipe, and makes effective use of exhaust pulsation because it is in the upstream part of the exhaust chamber. be able to. Furthermore, since the front reed valve device and the downstream part of the exhaust pipe are connected by piping, even if the joint pipe interposed between them is made of rubber, the thermal effect can be suppressed as much as possible, and the lead It is also advantageous in terms of vibration-proof connection between the valve and the supply pipe, and since the intermediate reed valve device is connected with piping, it is easy to adjust the length of the piping upstream and downstream of the reed valve, and it also reduces ventilation resistance. This can be done with optimal layout and adjustment.

Furthermore, since the reed valve device and the upstream piping of the reed valve device are disposed on the front side of the down tube, they are far from the knees of the occupant during operation, which is advantageous in terms of securing leg space.

As described above, the present invention has many advantages.

Furthermore, as shown by the chain line in Fig. 2, the air cleaner 23
A secondary air cutoff pipe (air intake cut valve) 3 is installed in the piping 28 connecting the reed valve device 25 and the reed valve device 25.
1 may be interposed to prevent the occurrence of afterburn by cutting off the supply of secondary air when the negative pressure in the exhaust pipe is extremely large, such as when the engine brake is activated.

[Brief explanation of the drawing]

The drawings show one embodiment of the present invention, in which Fig. 1 is a schematic side view of a motorcycle, Fig. 2 is a frame,
FIG. 3 is an enlarged side view of the engine section, FIG. 3 is a bottom view thereof, and FIG. 4 is a cutaway front view of essential parts of the reed valve device. In the drawings, 1 is a motorcycle, 2 is a frame, and 17
18 is an engine, 18 is an exhaust pipe, 19 is an exhaust chamber, 22 is a catalyst, 23 is an air cleaner, and 25 is a reed valve device.

Claims (1)

[Scope of utility model registration request] Equipped with a multi-cylinder engine with a horizontal V-shaped crankshaft, an air cleaner is installed between the front and rear cylinders, and the exhaust pipe of the front cylinder extends to the rear of the lower part of the frame and connects to the exhaust chamber installed at the lower rear of the frame. In addition, in motorcycles with a catalyst interposed in the exhaust system path downstream of the exhaust chamber, a reed valve device is installed in front of the frame that opens and closes with the exhaust pulsation of the front exhaust pipe and allows flow only from the inlet side to the outlet side. The reed valve device is disposed below the air cleaner, and the inlet of the reed valve device is connected to the air cleaner above by piping, and the outlet of the reed valve device is connected to the upstream part of the exhaust chamber of the exhaust pipe by piping. A secondary air supply device for an exhaust purification device for a motorcycle, characterized in that: