JPS595765B2 - Secondary air supply device for exhaust turbocharged engine - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention aims to purify unburned components such as HC7CO in the exhaust system of an engine equipped with a supercharger driven by an exhaust gas turbine, that is, an exhaust turbo supercharger. The present invention relates to a device for supplying secondary air.

Generally speaking, there are two ways to supply secondary air to the engine exhaust system: one is to use the pulsation of exhaust gas in the exhaust system to naturally suck in the secondary air, and the other is to use an air pump in the exhaust system to supply secondary air.
However, in exhaust turbocharged engines, the exhaust pulsation in the exhaust system is reduced by the exhaust turbine installed in the exhaust system, so depending on the exhaust pulsation, a sufficient amount of Secondary air cannot be supplied, and secondary air must be supplied under pressure using an air pump.
Engine output decreases by the amount of air pump drive, and fuel efficiency worsens.

It is also conceivable to install a constriction part such as a venturi, pipe orifice, or pipe nozzle in the middle of the exhaust system to create a flow trap where the pressure is low and to suck in secondary air, but the amount of exhaust gas from the engine changes greatly depending on the engine load, so if the aperture of the throttle part is set to match the amount of exhaust gas in the high load range, the specified amount of secondary air cannot be secured in the low load range, and the throttle part If the diameter of the engine is set to match the amount of exhaust gas in the low load range, the flow resistance of the exhaust gas will increase significantly in the high load range, which will not only increase the exhaust gas pressure from the engine and reduce the output, but also reduce the exhaust gas turbine output. efficiency will decrease.

The present invention provides a throttle section for sucking secondary air and a control valve that is linked to the engine load in parallel in the exhaust passage leading from the engine to the exhaust turbine. A predetermined amount of secondary air is sucked in by the flowing exhaust gas, and in high load ranges, part of the exhaust gas is bypassed through the throttle section to ensure a predetermined amount of secondary air, and the flow resistance of the exhaust gas is reduced. The aim is to reduce the

Next, an example of the present invention will be explained with reference to the drawings, in which 1 is an engine having an intake manifold 2 and an exhaust manifold 3, 3 is an exhaust turbine 5 and a blower-compressor 6.
7 indicates a muffler or a catalytic converter for discharging exhaust gas into the atmosphere, and the intake manifold 2 is provided with a fuel injection device 8 for each cylinder in the engine 1.

Further, the collecting part 9 of the intake manifold 2 is provided with a throttle valve 10 for increasing or decreasing the amount of air to the engine 1 (in this case, in other embodiments, a collecting part or a processor is installed instead of the fuel injection device). - A vaporizer may be provided on the suction side of the compressor), and the collecting section is connected to the discharge side of the blower-compressor 6 via the supercharging passage 11, and the suction side of the blower-compressor 6 is connected to the air flow. Air intake passage 1 with meter 14
It is connected to the air cleaner 13 via 2.

Further, the exhaust side of the exhaust turbine 5 is connected to the muffler 7 via an exhaust pipe 15, and the inlet side of the exhaust turbine 5 is connected to the exhaust manifold 3 via an exhaust passage 16.

A pipe nozzle 17 is provided in the middle of the exhaust passage 16 (preferably near the inlet side of the exhaust turbine 5), and a port 18 is provided at a position downstream of and close to the pipe nozzle 17, This port 18 is connected to a secondary air supply passage 20 with a check valve 21 whose tip is connected to an air suction filter 19 or the air cleaner 13, while a bypass passage 22 for the pipe nozzle 17 is provided in the exhaust passage 16. A control valve 23 is provided in the bypass passage 22, and is interlocked with the throttle valve 10 and opens and closes in substantially the same manner as the throttle valve 10.

In this case, a pipe orifice may be used in place of the pipe nozzle 17, a veturi may be used in place of the pipe nozzle 17, and the secondary air supply passage 20 may be connected to its throat;
The control valve 23Fi may be opened and closed in relation to the pressure of exhaust gas, or in relation to the engine load by other means (throttle opening, engine speed, intake pipe negative pressure, or a combination thereof).

In addition, the reference numeral 24 in the figure is an intake bypass passage that connects the supercharging passage 11 and the intake passage 12 by bypassing the blower compressor 6.
The passage 24 is provided with a plow-off valve 25 that opens during deceleration by rapidly closing the throttle valve 10, and reference numeral 26 connects the exhaust passage 16 and the muffler 7 or the exhaust pipe 15 by bypassing the exhaust turbine 5. In the exhaust detour, the passage 26 is provided with a wastegate valve 27 that opens when the supercharging exceeds the engine's critical speed and becomes supercharging.

In this configuration, exhaust gas discharged from the engine during operation of the engine is transferred from the exhaust passage 16 to the exhaust turbine 5.
The engine enters the engine, rotates the exhaust turbine 5, and rotationally drives the blower-compressor 6 directly connected thereto.

In this case, in a low load range where the opening degree of the throttle valve 10 is small, the amount of intake air is small, and therefore the amount of exhaust gas is small, and the rotation of the turbocharger 14 is slow, so that so-called turbocharging cannot be performed. In this state, the control valve 23 in the bypass passage 22 is closed, so all the exhaust gas from the engine 1 passes through the pipe nozzle 17 and enters the port 1 downstream of it.
Since a low pressure field is formed at 8, secondary air is sucked into the area through the secondary air supply passage 20 and mixed with the exhaust gas, and the amount of exhaust gas in this low load area is reduced. By setting the diameter of the pipe nozzle 17 in advance, a predetermined amount of secondary air can be secured in the low load range.

In a high load range with the throttle valve 10 wide open, the amount of exhaust gas increases as the amount of intake air increases.
The rotation of the turbo supercharger 4 becomes faster, resulting in a so-called turbo supercharging state.

In this state, the control valve 23 in the bypass passage 22 does not open due to the increase in load, so the exhaust gas from the engine 1 flows through both the pipe nozzle 17 and the bypass passage 22, and some of the exhaust gas flowing through the pipe nozzle 17 flows through the pipe nozzle 17 and the bypass passage 22. While secondary air is sucked from the secondary air supply passage 20 by the exhaust gas, some of the exhaust gas from the engine is sucked into the bypass passage 22.
through the pipe nozzle 1 with almost no pressure loss.
7 and merges with the exhaust gas from the tube nozzle 17, and the pressure after the merge becomes approximately equal to the average pressure before and after the tube nozzle 17.

Therefore, the pressure loss between the front and back of the pipe nozzle 17 is such that the total amount of exhaust gas is adjusted to the amount of exhaust gas in the low load range.
This can be reduced to an incomparable extent compared to the case where it passes through 7.

Therefore, according to the present invention, it is possible to reliably supply a predetermined amount of secondary air over the entire load range of a turbocharged engine by means of a constriction section such as a pipe nozzle provided in the exhaust passage, and the HC2C
While it is possible to accurately purify unburned components such as O, the bypass passage with a control valve provided for the throttle section prevents an increase in engine exhaust pressure and a decrease in exhaust turbine efficiency in a high load range, thereby improving engine efficiency. It has the effect of improving output.

[Brief explanation of the drawing]

The drawing is a diagram of an apparatus according to an embodiment of the present invention. 1... Engine, 4... Exhaust turbo supercharger, 5... Exhaust turbine, 6... Prower compressor, 16...・Exhaust passage, 1T...
... Pipe nozzle, 20 ... Secondary air supply passage,
22...Bypass passage, 23...Control valve.

Claims (1)

[Claims] 1. In an engine equipped with an exhaust turbo supercharger, a constriction part is provided in the exhaust passage leading from the engine to the exhaust turbo supercharger@exhaust turbine, and a bypass passage for the constriction part is provided, and the engine 1. A secondary air supply device for an exhaust turbocharged engine, characterized in that a control valve is provided that is linked to a load, and a secondary air supply passage is connected to the throttle portion.