JPS63208612A - Exhaust controller for engine - Google Patents

Abstract

PURPOSE:To enhance assembling and maintenance of exhaust control valves by composing the exhaust control valves of holders and valve discs held rotatably by said holders and attaching said exhaust control valves detachably to an expansion chamber after they are previously assembled. CONSTITUTION:The exhaust system of an engine has a pair of exhaust pipes 20, 22 which extend from the front surface of a front bank through right and left sides of a crankcase to the back, and a pair of exhaust pipes 24, 26 which extend from the back surface of a rear bank downward on the back of the engine. In addition, an expansion chamber 28 to which the downstream sides of respective exhaust pipes are connected, and a pair of exhaust mufflers 30, 32 are provided. In the expansion chamber, respective exhaust control valves 34, 36 which face respective opening ends of respective exhaust pipes are provided. In the above construction, respective exhaust control valves are previously assembled before they are attached to the inside of the expansion chamber. Namely, after one side shaft of a valve disc 40 is inserted the through the bearing plate 42 of a holder 38, the other side shaft is inserted into a bearing arm 46 so that the bearing arm is fixed to a substrate 44.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to an exhaust control device for an engine in which an exhaust control valve is installed in an exhaust pipe.

(Background of the Invention) It is known that in 4-stroke engines, 2-stroke engines, etc., exhaust gas is intermittently guided into the exhaust pipe by opening and closing the exhaust valve, causing an inertial effect and a pulsation effect of the exhaust gas in the exhaust pipe. . These effects (referred to as dynamic effects) vary depending on engine speed. Therefore, if this dynamic effect is maximized to increase the volumetric efficiency at the rotational speed, the dynamic effect acts in the opposite direction at other rotational speeds, resulting in a significant decrease in the volumetric efficiency. Therefore, if the exhaust system specifications (exhaust pipe length, exhaust pipe diameter, etc.) are set so that this dynamic effect is optimal in the high speed range, the torque will significantly decrease (torque trough) in the medium speed range. There was a problem that occurred.

Therefore, it is proposed to install an exhaust control valve in the exhaust pipe to change the area of the exhaust flow path, reducing the flow path area in the rotation speed range where the volumetric efficiency decreases, and increasing the flow path area in other rotation speed ranges. (Japanese Patent Application No. 60-263752). In this case, it is desirable that the exhaust control valve be provided near the downstream end of the exhaust pipe, that is, the opening end to the expansion chamber, so as to effectively cancel out the positive and negative pressure waves of the exhaust, as will be described later.

Furthermore, in a multi-cylinder engine, if the downstream sides of each exhaust pipe are merged in an expansion chamber, exhaust interference between the cylinders may cause a decrease in body exertion rate and a decrease in torque. Therefore, it has been proposed to reduce the exhaust flow area by providing an exhaust control valve for each exhaust pipe and closing this control valve in the rotational speed range where the adverse effect of exhaust interference occurs (Japanese Patent Application No. 60-2837
No. 53).

It is also being considered to improve combustion by controlling the back pressure in the exhaust pipe, and to control exhaust components by controlling self-EGR (exhaust gas recirculation).

As described above, it is conceivable to provide an exhaust control valve in the expansion chamber to change the area of the exhaust flow path for various purposes such as improving volumetric efficiency, improving combustion, and controlling exhaust components.

However, when the exhaust control valve is installed in the expansion chamber in this manner, it is required that the exhaust control valve be easily assembled.

Furthermore, since carbon and the like tend to adhere to the bearings of this valve, it is also required that the bearings be easy to inspect and maintain.

(Object of the Invention) The present invention has been made in view of the above circumstances, and provides an engine exhaust control device in which the exhaust control valve is easy to assemble and maintainable when the exhaust control valve is provided in the expansion chamber. The purpose is to provide

(Structure of the Invention) According to the present invention, this object is provided in an engine including an expansion chamber connected to the downstream side of an exhaust pipe, and an exhaust control valve housed in the expansion chamber and changing the exhaust flow path area of the exhaust pipe. , the exhaust control valve includes a holder and a valve body rotatably held by the holder, and the exhaust control valve is detachably attached to the expansion chamber in a preassembled state. This is achieved by a characteristic engine exhaust control device.

(Embodiment) Fig. 1 is a partially sectional plan view of an embodiment of the present invention, and Fig. 2 is a partially sectional plan view of an embodiment of the present invention.
The figure is a side view, and Figure 3 is a partially sectional rear view.
FIG. 4 is a side view of a motorcycle using this, FIG. 5 is a plan view of this exhaust system, and FIG. 6 is a side view of the same.

In FIG. 4, reference numeral 10 is a 4-cycle, 4-cylinder V-type engine, which is mounted near the center of the vehicle body. This engine 10 has a crankshaft (not shown) disposed in the vehicle width direction, and the front cylinder 12 and rear cylinder 14, which form a V-shape in side view, are separated in the front-rear direction to form a so-called front-rear V-type engine. .

The exhaust system of the engine 10 includes exhaust pipes 20, 22 extending rearward from the front surface of the front bank 12 through the left and right lower portions of the crankcase 16, and exhaust pipes 24.22 extending rearward from the rear surface of the rear bank 14 downwardly behind the engine 10. 26, and the expansion chamber 2 to which the downstream sides of these exhaust pipes 20, 22, 24, and 26 are connected.
8 and two exhaust mufflers 30 and 32. Note that the expansion chamber 28 is located below and rearward of the engine 10.

Disposed within the expansion chamber 28 are an exhaust control valve 34 facing the open end of the exhaust pipe 20.24 and an exhaust control valve 36 facing the open end of the exhaust pipe 22.26. Re-exhaust control valve 34.36
are symmetrical, so below, the left exhaust control valve 34 is referred to as the first to
This will be explained based on Figure 3.

As shown in FIG. 1, the exhaust control valve 34 includes a cast holder 38 and a crank-shaped valve body 40 rotatably held by the holder 38.

The holder 38 includes a bearing plate 42 that is removably attached to the left side of the expansion chamber 28, and a substrate 44 that is integrally formed with the bearing plate 42.
A bearing arm 46 (see FIG. 3) is screwed to this base plate 44. The portion of the valve body 40 facing the open end of the exhaust pipe 20.24 has an arcuate cross section. Valve body 40
The left shaft passes through the bearing plate 42 and projects outward, and a pulley 48 is fixed to this projecting end. Left and right exhaust control valves 3
4.36 pulleys 4B and 4B each have wires 50 (
6) is wound around the valve body 4 via this wire 50.
0 is rotated by a drive device such as a servo motor 52. Note that this motor 52 is controlled by a control device 56 in accordance with the engine rotation speed detected from an ignition device 54.

In Fig. 4, 58 is the front fork, 60 is the front wheel, and 6 is the front fork.
2 is a handlebar, 64 is a rear arm attached to the pivot shaft 66 so as to be able to swing up and down, 68 is a rear wheel attached to the rear end of this rear arm 66, 70 is a cushion unit, 72 is a fuel tank, and 74 is a driver's seat. It is.

Next, the operation of this embodiment will be explained. When the diameter and length of the exhaust pipes 20 to 26 are set so that the volumetric efficiency is high in the high speed range of the engine 10, the exhaust control valve 34.3
6 is driven by a servo motor 52 so as to close in a low to medium speed range and open in a high speed range.

A positive pressure wave caused by the opening of the exhaust valve of the engine 10 propagates inside the exhaust pipes 20 to 26 at the speed of sound, and a negative pressure wave generated by rapid expansion at the open end of the exhaust pipe travels back through the exhaust pipes 20 to 26 at the speed of sound. It propagates in the direction and returns to the exhaust valve of the engine IO. If the exhaust control valves 34 and 36 are closed, the positive pressure waves caused by the opening of the exhaust valves are reflected by the exhaust control valves 34 and 36 and returned to the exhaust valves as positive pressure waves at the speed of sound.

Therefore, in the low and medium speed range where the dynamic effect acts in the opposite direction, the exhaust control valve 34.
36, the negative pressure waves generated and returned by the open ends of the exhaust pipes 20-26 cancel out the positive pressure waves reflected by the exhaust control valves 34, 36. At this time, the pulsation effect is canceled and the volumetric efficiency decreases in the medium speed range (
(occurrence of torque valley) can be suppressed.

Further, when the exhaust control valves 34, 36 are used for the purpose of preventing torque reduction due to exhaust interference between cylinders, the exhaust control valves 34, 36 may be closed in a rotation range where the torque reduction due to exhaust interference is significant. In addition, exhaust control valve 34.36
It is possible to use a device that reduces the area of the exhaust flow path to about 10 to 30% in this closed state.

The exhaust control valves 34 , 36 are preassembled before assembly into the expansion chamber 28 . That is, the bearing plate 4 of the holder 38
After one shaft of the valve body 40 is inserted into the valve body 2, a bearing arm 46 is inserted into the other shaft, and this bearing arm 46 is fixed to the base plate 44 with screws. After pre-assembling in this way, this assembly is inserted into the expansion chamber 28 through the window 28a (FIGS. 1 to 3) provided on the side of the expansion chamber 28, and the bearing plate 42 is screwed to the side of the expansion chamber 28. . Furthermore, by fixing the substrate 44 to the bottom of the expansion chamber 28 with screws, the exhaust control valves 34 and 36 can be attached to the bottom of the expansion chamber 28.
mounted on.

Therefore, by removing appropriate screws, this assembly can be removed from the expansion chamber 28, making it easy to inspect and maintain the bearing portion, and to remove adhering carbon.

In the exhaust control valves 34 and 36 of the above embodiments, the valve body 40 having an arcuate cross section faces the opening of the exhaust pipe, but the present invention may also use valves of other structures, such as butterfly valves.

(Effects of the Invention) As described above, when the exhaust control valve is provided in the expansion chamber, the present invention pre-assembles the exhaust control valve and removably attaches the assembly to the expansion chamber. The control valve is easy to assemble. Furthermore, the bearings and other parts can be maintained and inspected with the exhaust control valve removed, and carbon removal work can also be done, so work efficiency is good.

[Brief explanation of the drawing]

FIG. 1 is a partially sectional top view of one embodiment of the present invention, and FIG.
The figure is a side view, and Figure 3 is a partially sectional rear view.
FIG. 4 is a side view of a motorcycle using this exhaust system, FIG. 5 is a plan view of this exhaust system, and FIG. 6 is a side view of the exhaust system. 10...■ type 4-cylinder engine, 12...front bank, 14...rear bank, 20-26...exhaust pipe, 28...expansion chamber, 34.36...exhaust control valve, 38...Holder, 40...Valve body.

Claims (1)

[Claims] In an engine including an expansion chamber connected to the downstream side of an exhaust pipe, and an exhaust control valve housed in the expansion chamber to change an exhaust flow path area of the exhaust pipe, the exhaust control valve includes a holder and a circuit connected to the holder. 1. An engine exhaust control device comprising: a movably held valve body; the exhaust control valve being removably attached to the expansion chamber in a preassembled state.