JPH03194120A - Exhaust device for engine - Google Patents

Abstract

PURPOSE:To improve engine output and reduce exhaust noise by communicating the pressure intensification/reduction operating chamber of a pressure intensifying/reducing device, timing interlocked with a crankshaft, connectedly with an exhaust passage, and reducing/intensifying the pressure of the exhaust passage according to the rise/fall of exhaust pulsating pressure. CONSTITUTION:The pressure intensification/reduction operating chamber 5 of a pressure intensifying/reducing device 4 is communicated with an exhaust passage 3 communicated with the cylinder chamber 2 of a multiple cylinder diesel engine 1 through an exhaust port 15. The pressure intensifying/reducing device 4 provided with a diaphragm 23 reciprocated through gear trains 24, 25 and an interlocking crank 22 timing interlocked with a crankshaft 6 is constructed in such a way as to reduce the pressure of the exhaust passage 3 at the exhaust pulsating pressure rising time of the exhaust passage 3 and intensify the pressure of the exhaust passage 3 at the exhaust pulsating pressure falling time. The rise of exhaust pulsating pressure is thereby suppressed at its rising time so as to heighten the scavenging efficiency of the cylinder chamber 2 to improve engine output, and the fall of exhaust pulsating pressure is suppressed at its falling time so as to minimize the fluctuation of exhaust pulsating pressure to minimize exhaust noise.

Description

[Detailed description of the invention] [Industrial application field] The present invention relates to an engine exhaust system.

[Prior Art] Conventionally, an engine exhaust system does not include a means for suppressing pressure fluctuations in exhaust pulsation pressure in an exhaust passage.

[Problem to be solved by the invention] Therefore, the above conventional technology has the following problems.

■The pressure fluctuations in the exhaust pulsating pressure in the exhaust passage are large, and when the exhaust pulsating pressure rises, the exhaust back pressure increases, so the scavenging efficiency in the cylinder chamber decreases and the engine output performance decreases.

■Exhaust noise is large due to large pressure fluctuations in the exhaust pulsating pressure in the exhaust passage.

An object of the present invention is to suppress pressure fluctuations in exhaust pulsating pressure.

[Means for Solving the Problems] The present invention is characterized in that an engine exhaust system is configured as follows.

For example, as shown in FIGS. 1 to 3, an exhaust passage 3 is communicated with the cylinder chamber 2 of the engine 1, a pressure increase/decrease working chamber 5 of a pressure increase/decrease device 4 is communicated with the exhaust passage 3, and the pressure increase/decrease device 4 is connected. The pressure increasing/decreasing device 4 is timed in conjunction with the crankshaft 6, and is configured to reduce the pressure in the exhaust passage 3 at a rising time 8 of the exhaust pulsating pressure 7 in the exhaust passage 3, and to increase the pressure at a falling time 9.

The pressure increase/decrease device 4 may be one that increases or decreases the pressure in the exhaust passage 3 by operating a diaphragm 23, as shown in FIG. 2, for example, or one that increases or decreases the pressure in the exhaust passage 3 by operating a plunger.

[effect] The present invention provides the following effects (1) and (2).

■When the exhaust pulsating pressure in the exhaust passage increases, the pressure increasing/decreasing device reduces the pressure in the exhaust passage to reduce the increase in exhaust pulsating pressure.
Since the exhaust back pressure is reduced, the scavenging efficiency in the cylinder chamber is increased, and the output performance of the engine can be improved.

■When the exhaust pulsating pressure in the exhaust passage increases, the pressure increasing/decreasing device reduces the pressure in the exhaust passage to reduce the increase in exhaust pulsating pressure, and when the exhaust pulsating pressure in the exhaust passage decreases,
The pressure increasing/decreasing device increases the pressure in the exhaust passage to reduce the drop in the exhaust pulsating pressure, thereby reducing fluctuations in the exhaust pulsating pressure, thereby reducing exhaust noise.

■The pressure increase/decrease device is linked at a speed that corresponds to the rotational speed of the crankshaft, and the timing of the pressure increase/decrease operation is automatically adjusted according to changes in the engine speed, so the pressure increase/decrease device is activated. This can be done with accurate timing regardless of engine speed.

[Example] Embodiments of the present invention will be described based on the drawings.

Figures 1 to 3 are diagrams for explaining the exhaust system for an engine according to the present invention, in which Figure 1 is a partially vertical cross-sectional front view of the engine, Figure 2 is a partially cutaway side view of the engine, and Figure 3 is a partially cutaway side view of the engine. 7 is a graph showing fluctuations in exhaust pulsating pressure in an exhaust passage.

In FIG. 1 or 2, reference numeral 1 indicates an engine.

This engine 1 is a multi-cylinder diesel engine, in which air is drawn from an air cleaner (not shown) into each cylinder chamber 2 by passing through an intake passage 11 in an intake manifold 10 and an intake boat 12 in order, and fuel is pumped into a fuel injection pump. The fuel is injected from the fuel injection nozzle 14 by the pumping force of 13 and combusted,
The combustion gas is made to pass from each cylinder chamber 2 through an exhaust port 15, an exhaust passage 3 in an exhaust manifold 16, and a muffler 17 in order, and is released into the atmosphere.

In addition, the intake/exhaust operation is performed by transmitting the rotational force of the crankshaft 6 through the crank gear 18, the idle gear 19, and the valve gear 20 in order to open and close the intake valve (not shown) and the exhaust valve 21 at predetermined timings. It is supposed to be done.

An exhaust passage 3 is communicated with the cylinder chamber 2 of the engine 1,
A pressure increasing/decreasing chamber 5 of a pressure increasing/decreasing device 4 is communicated with the exhaust passage 3;
The pressure increasing/decreasing device 4 is timed in conjunction with the crankshaft 6, and the pressure increasing/decreasing device 4 reduces the pressure in the exhaust passage 3 at the rising time 8 of the exhaust pulsating pressure 7 of the exhaust passage 3 shown in FIG. By configuring to increase the pressure, the pressure increasing/decreasing device 4 reduces the pressure in the exhaust passage 3 at the rising timing 8 of the exhaust pulsating pressure 7 in the exhaust passage 3, and the increase in the exhaust pulsating pressure 7 becomes the state shown by the chain line. The goal is to reduce the exhaust back pressure to the solid line.

Therefore, the scavenging efficiency of the cylinder chamber 2 is increased, and the output performance of the engine 1 can be improved.

Further, as shown in FIG. 3, the exhaust pulsating pressure 7 of the exhaust passage 3
At rising time 8, the pressure increase/decrease operating device 4 opens the exhaust passage 3
The increase in the exhaust pulsating pressure 7 is reduced from the state shown by the chain line to the state shown by the solid line, and at the time 9 when the exhaust pulsating pressure 7 in the exhaust passage 3 falls, the pressure increasing/decreasing device 4 Increase the pressure in the exhaust passage 3 to lower the exhaust pulsating pressure 7,
What should be a chain line state is reduced to a solid line state, and fluctuations in the exhaust pulsating pressure 7 are reduced, so exhaust noise can be reduced.

Furthermore, the pressure increase/decrease device 4 is interlocked at a speed corresponding to the rotational speed of the crankshaft 6, and the timing of the operation of the pressure increase/decrease device 4 is automatically adjusted according to changes in the rotational speed of the engine 1. The device 4 can be operated at accurate timing regardless of the rotational speed of the engine 1.

The pressure increasing/decreasing device 4 has a pressure increasing/decreasing working chamber 5 disposed below the interlocking crank 22, and a diaphragm 2 on the upper surface of the pressure increasing/decreasing working chamber 5.
3, the interlocking crank 22 is connected to the crankshaft 6 for timing through a driving gear 24 and a driven gear 25, and the diaphragm 23 is interlockingly connected to the interlocking crank 22 through a connecting rod 26. Exhaust pulsating pressure of 7'
- At the H period 8, the diaphragm 23 is raised, the exhaust gas in the exhaust passage 3 is sucked into the pressure increasing/decreasing chamber 5, and the exhaust passage 3 is depressurized. The flamm 23 is lowered to release the exhaust gas previously sucked into the pressure increase/decrease working chamber 5 into the exhaust passage 3, thereby increasing the pressure in the exhaust passage 3.

[Brief explanation of drawings]

1 to 3 are diagrams explaining the exhaust system for an engine according to the present invention, in which FIG. 1 is a partially vertical cross-sectional front view of the engine, FIG. 2 is a partially cutaway side view of the engine, and FIG. 3 is a partially cutaway side view of the engine. 7 is a graph showing fluctuations in exhaust pulsating pressure in an exhaust passage. 1. Engine, 2. Cylinder chamber, 3. Exhaust passage.
4. Pressure increase/decrease device, 5. Pressure increase/decrease operating chamber, 6. Crankshaft,
7...Exhaust pulsating pressure, 8...7 rise timing, 9...7
period of decline.

Claims (1)

[Claims] 1. An exhaust passage 3 is communicated with the cylinder chamber 2 of the engine 1, a pressure increase/decrease working chamber 5 of a pressure increase/decrease device 4 is communicated with the exhaust passage 3, and the pressure increase/decrease device 4 is adjusted with the crankshaft 6. An exhaust system for an engine, characterized in that the pressure increasing/decreasing device 4 is configured to reduce the pressure in the exhaust passage 3 when the exhaust pulsating pressure 7 in the exhaust passage 3 rises (8) and to increase the pressure when the exhaust pulsation pressure (7) in the exhaust passage 3 falls.