JP2654967B2 - Engine exhaust control valve device - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to an exhaust control valve device that changes an opening area near a downstream end of an exhaust pipe of a multi-cylinder engine in accordance with an operation state.

BACKGROUND OF THE INVENTION It is known that an exhaust control valve for changing an opening area is provided near an exhaust pipe downstream end of an engine, and the opening is controlled in accordance with an operation state to improve performance such as engine output. is there.

Generally, exhaust gas expands abruptly at the downstream end of the exhaust pipe, and the negative reflected wave at this time flows back through the exhaust pipe and acts on the exhaust valve of the engine. In a high-speed type engine, the exhaust system is set such that the negative reflected wave flowing backward at a high speed acts to promote the exhaust to increase the high-speed output. However, in this high-speed engine, at a middle speed, the negative reflected wave acts to hinder exhaust, and the output decreases. Therefore, at the middle speed, the exhaust control valve is almost half-opened, and the negative reflected wave generated at the downstream end of the exhaust pipe and flowing backward is canceled out by the positive reflected wave reflected by the exhaust control valve and flowing backward. Is to increase the torque. In a low-speed range, the exhaust valve is closed to prevent fresh air from flowing through the combustion chamber, thereby stabilizing idling operation.

In the case of a multi-cylinder engine, it is preferable that the exhaust control valve be provided independently for each cylinder. However, this causes a problem that the exhaust system becomes large and it is difficult to mount the exhaust system on a vehicle. In particular, the mounting space is severely restricted. This is a major problem for some motorcycles.

(Object of the Invention) The present invention has been made in view of such circumstances,
An object of the present invention is to provide an exhaust control valve device for a multi-cylinder engine capable of reducing the size of an exhaust system when such an exhaust control valve is provided in a multi-cylinder engine.

(Constitution of the Invention) According to the present invention, an object of the present invention is to provide an exhaust control valve, which is controlled to change an exhaust passage area in accordance with an operation state of an engine, near an opening end where an exhaust pipe opens to an expansion chamber. In the engine, the exhaust pipes of the cylinders having different ignition timings are gathered by a collecting pipe and guided to an expansion chamber, and the exhaust control valve is arranged near an opening end of the collecting pipe opening to the expansion chamber. This is achieved by a characteristic exhaust control valve device for a multi-cylinder engine.

It is desirable that the cylinders assembled here do not overlap in the exhaust period. In the case of a two-cylinder engine, it is desirable that the cylinders ignite (exhaust) at equal intervals. It is desirable to collect cylinders having no overlap.

(Embodiment) FIG. 1 is a block diagram of an embodiment of the present invention, FIG. 2 is a side view of a motorcycle to which the embodiment is applied, FIG. 3 is an enlarged view of a part of the motorcycle, and FIG. Is a plan view, FIG. 5 is a front view, FIG. 6 is a cross-sectional view of the exhaust control valve, and FIGS. 7, 8, and 9 are left, right, and bottom views thereof.

In FIG. 2, reference numeral 10 denotes a parallel four-cylinder four-cycle engine, which is mounted near the center of the vehicle body and covered by a cowling 12. 14 is a front wheel, 16 is a rear wheel, 18 is a steering handlebar, 20 is a cover for covering an air cleaner and a vertically long fuel tank (both are not shown), and 22 is a driving seat.

The engine 10 includes a cylinder 26 that rises obliquely forward from the upper surface of the front part of the crankcase 24. This cylinder 26
Is a group of cylinders of four cylinders arranged in the width direction of the engine, and the upper part thereof is a cylinder head 28 having a built-in intake / exhaust valve and its valve operating mechanism. Cylinder 26
The rear surface is connected to a down-draft type vaporization type (not shown). This carburetor is a four-unit type having four carburetors connected to each cylinder. The upper end of the vaporizer is connected to an air cleaner located above the vaporizer.

Next, the exhaust system 50 will be described. The exhaust system 50 includes four exhaust pipes 52 (52a to 52d) independently connected to each of the cylinders I, II, III, and IV of the engine 10. The exhaust pipes 52 of the two cylinders are assembled.
For example, each of the cylinders I to IV is referred to as I-II-IV-III or I-III
When the ignition is performed in the order of -IV-II, the exhaust pipes 52a and 52d of the cylinders I and IV are collected in the collecting pipe 54a, and the exhaust pipes 52b and 52c of the cylinders II and III are collected in the collecting pipe 54b. As a result, exhaust gas is guided to the collecting pipes 54a and 54b at intervals of 360 degrees in crankshaft angle. Each exhaust pipe 52 descends from the front surface of the cylinder 26 and passes below the crankcase 24 and is connected to the collecting pipe 54. The exhaust pipes 52a and 52d of the outer cylinders I and IV are connected to the inner cylinders II and III. Pass over the exhaust pipes 52b and 52c (fifth
FIG.), The length of each exhaust pipe 52 is considered as uniform as possible. A recess 58 is formed on the lower surface of the oil pan 56 at the lower portion of the crankcase 24. The recess 58 passes in the front-rear direction, and a part of each exhaust pipe 52 and the collecting pipe 54 is located in the recess 58 so that the distance from the road surface (road Clearance).

Reference numeral 60 denotes an exhaust control valve, which is located below and behind the engine 10. As shown in FIGS. 6 to 9, the control valve 60 has a vertically-long rectangular body 62, horizontally-long rectangular passages 62a and 62b which open in the body 62 in two stages, and vertically penetrates these passages 62a and 62b. And a rectangular valve plate 66 (66a, 66b) fixed to the valve shaft 64, and a pulley 68 provided at the lower end of the valve shaft 64. Connecting pipe 70 (70a, 70
The respective collecting pipes 54 are connected via b). That is, while each of the collecting pipes 54a and 54b is a pipe having a circular cross section, the passages 62a and 62b of the body 62 are rectangular,
One end is circular and fitted and pressed against the collecting pipe 54, and the other end is fixed to a flange 72 in a rectangular shape, and the flange 72 is bolted to the body 62. A second collecting pipe 76 forming an expansion chamber 74 is connected to the right (rear) surface of the body. That is, a flange 78 is fixed to the rectangular opening of the collecting pipe 76, and the flange 78 is bolted to the body 62, while a rear exhaust pipe 80 is fitted to the circular opening of the collecting pipe 76, and It is pressed and connected by the like. An exhaust muffler 82 is connected to the rear exhaust pipe 80.

The ends of two wires 84 are locked to a pulley 68 provided on the valve shaft 64 of the exhaust control valve 60, and the other ends of these wires 84 are connected to a servomotor 86 (see FIG. 2).

The servo motor 86 is controlled by a control device 88 (FIG. 1) composed of a microcomputer, and opens and closes the valve plate 66. That is, the control device 88 opens and closes the valve plate 66 in accordance with characteristics stored in advance based on a signal indicating an operating state such as the engine rotation speed, and generates optimum engine performance. For example, during idling, the valve plate 66 is sufficiently closed to prevent fresh air from flowing through the combustion chamber and stabilize the operation. In the speed range where a torque valley occurs, the valve plate 66 is set to a substantially half-open position, and the negative reflected wave at the opening end and the positive reflected wave reflected by the valve plate 66 cancel out the torque valley near the engine exhaust valve. Increases the torque in the rotation range where the torque occurs. At high speed, the valve plate 66 is fully opened to obtain high output.

(Effect of the Invention) As described above, the present invention collects the exhaust pipes of the cylinders whose ignition timings are distant from each other, guides them to the expansion chamber, and arranges the exhaust control valve near the open end of the collecting pipe. Therefore, there is no need to provide an exhaust control valve independently for each cylinder, which has the effect of simplifying the configuration of the exhaust system and achieving downsizing.

[Brief description of the drawings]

FIG. 1 is a block diagram of one embodiment of the present invention, FIG. 2 is a side view of a motorcycle to which the present invention is applied, FIG. 3 is an enlarged view of a part of the motorcycle, FIG. FIG. 5 is a front view, and FIG.
The figures are cross-sectional views of the exhaust control valve, and FIGS. 7, 8, and 9 are a left side view, a right side view, and a bottom view thereof. 10 Engine 50 Exhaust system 52 Exhaust pipe 54 Collecting pipe 60 Exhaust control valve 74 Expansion chamber

Claims (1)

(57) [Claims] 1. An exhaust pipe in the vicinity of an opening end opening to an expansion chamber,
In an engine provided with an exhaust control valve that is controlled to change the exhaust passage area in accordance with the operating state of the engine, the exhaust pipes of the cylinders whose ignition timings are distant are gathered by a collecting pipe and guided to an expansion chamber. An exhaust control valve device for a multi-cylinder engine, wherein the exhaust control valve is disposed near an opening end where a collecting pipe opens to an expansion chamber.