JPS644052B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a secondary air supply device for an internal combustion engine that supplies secondary air to an exhaust passage of an internal combustion engine equipped with a turbocharger to purify exhaust gas.

(Prior art) Conventionally, secondary air is supplied to the exhaust passage of an internal combustion engine to combust unburned components such as carbon monoxide (CO) and hydrocarbons (HC) in the exhaust gas, thereby reducing CO and
Methods have been adopted to reduce HC emissions.

(Problem to be solved by the invention) In particular, when the engine rotation speed range is wide, such as in motorcycles, it is necessary to maintain the discharge characteristics of the turbocharger, match the air amount required by the engine, and then provide appropriate secondary air. must be supplied to the exhaust passage to achieve exhaust purification.

The present invention was made to solve this problem, and maintains the discharge characteristics of the turbocharger.
Not only can exhaust purification be achieved by matching the amount of air required by the engine, but also secondary air is supplied to the exhaust passage without the need for a special exhaust re-burning device in the exhaust passage, even in the engine's high-speed operating range. This makes it possible to re-burn and reliably reduce the unburned components of CO and HC in this exhaust passage, and it also has a simple structure, is inexpensive, has excellent durability, and is easy to maintain. The object of the present invention is to provide a secondary air supply device for an internal combustion engine.

(Operation) The intake air pressurized by the turbocharger is temporarily stored in the resonance chamber and pre-chamber. The resonance chamber adjusts the natural frequency of the intake passage between the compressor and pre-chamber of the turbocharger, thereby damping pressure vibrations within the intake passage. In addition, pressure vibrations within the intake passage are damped by the action of the pre-chamber, and the air flow is changed to a substantially constant pressure. This air is then supplied from the pre-chamber to the exhaust passage via the secondary supply passage, and unburned components such as CO and HC are re-burned within this exhaust passage. Further, when the pressure in the pre-chamber becomes lower than the pressure in the exhaust passage, the check valve closes and the exhaust gas does not flow back to the pre-chamber side.

(Example) Hereinafter, an example of the present invention will be described with reference to the drawings. In the figure, numeral 1 indicates an internal combustion engine,
Intake port 1 equipped with intake valve 1a of this engine 1
An intake pipe (intake passage) 2 and an exhaust pipe (exhaust passage) 3 are attached to the exhaust port 1d equipped with the exhaust valve 1c and the exhaust valve 1c, respectively.
are connected. An air cleaner 4 is provided at the open end of the intake pipe 2. A compressor 5a of a turbocharger 5 and a pre-chamber 6 for temporarily storing intake air pressurized by the turbocharger 5 are arranged in the intake pipe 2 in this order toward the intake port 1b. Inside the exhaust pipe 3,
An exhaust turbine 5b of the turbocharger 5 is disposed, and the exhaust turbine 5b is connected to the compressor 5a.
The drive shaft 5c is connected to the drive shaft 5c. A muffler 7 is provided at the discharge end of the exhaust pipe 3. The upstream and downstream sides of the exhaust turbine 5b of the exhaust pipe 3 are connected by a waist pipe 8. A waste gate valve 9 is disposed in the middle of this waste pipe 8. The inside of the casing of this wastegate valve 9 is provided with an operating pressure chamber 9 by a diaphragm 9b.
c and an atmospheric pressure chamber 9d. This working pressure chamber 9c is connected to the compressor 5 through a pipe 10.
It communicates with the intake pipe 2 portion between the prechamber 6 and the prechamber 6. When the working pressure in the working pressure chamber 9c is below a predetermined value, the diaphragm 9b is moved to the working pressure chamber 9 by the pressing force of the spring 9e attached to the atmospheric pressure chamber 9d.
The valve body 9a, which is displaced toward the c side and is integrally attached to the diaphragm 9b, comes into contact with a valve seat 8a provided on the waist pipe 8, thereby shutting off the waist pipe 8. An open end 11a of a secondary air supply path 11 made of piping is opened near the exhaust port 1d, and the pre-chamber 6 and the exhaust pipe 3 are communicated through the secondary air supply path 11. A check valve 1 is provided in the middle of this secondary air supply path 11.
2 is provided. The check valve 12 includes, for example, an upper chamber 1 which is partitioned by a partition wall 12a and communicates with the pre-chamber 6 and the exhaust pipe 3, respectively, as shown in the figure.
2b and the lower chamber 12c, and the lower chamber 12 of the partition wall 12a.
c. Hole 1 of the partition wall 12a is attached to the side surface.
This is a differential pressure responsive valve composed of a reed 2d and a reed 12e that opens and closes.

In the figure, reference numeral 13 indicates a resonance chamber, 14 indicates a throttle valve, and 15 indicates a fuel injection valve that supplies fuel to the engine 1.

Next, the operation of the secondary air supply system for an internal combustion engine configured as described above will be explained.

Air supplied to the engine 1 is passed through an air cleaner 4 to a compressor 5 of a turbocharger 5.
It is pressurized at a and temporarily stored in the pre-chamber 6,
After that, the throttle valve 14 adjusts the amount to the engine 1.
is supplied to The prechamber 6 attenuates pressure fluctuations (pulsations) in the intake air and supplies air with a substantially constant pressure to the engine 1, and has the effect of suppressing output fluctuations due to fluctuations in the intake air amount of the engine 1. . Further, the resonance chamber 13 has a function of adjusting the natural frequency of the intake pipe 2 portion between the compressor 5a and the pre-chamber 6, and damps pressure vibrations within the intake pipe 2.

On the other hand, when the exhaust gas collides with the exhaust turbine 5b, the exhaust turbine 5b is rotationally driven, and the compressor 5a, which is connected to the exhaust turbine 5b via the drive shaft 5c, is rotated. The intake air is compressed by the compressor 5a. The exhaust gas that has passed through the exhaust turbine 5b is muffled while passing through the muffler 7, and then is released into the atmosphere. As the rotation speed of the engine 1 increases, the supercharging pressure by the turbocharger 5 increases, so the pressure in the pre-chamber 6 increases, and when this pressure exceeds a predetermined value, it is transmitted through the pipe 10 to the operating pressure chamber 9c of the wastegate valve 9. The pressure acts on the diaphragm 9b, resisting the pressing force of the spring 9e, and displacing the diaphragm 9b to the right in the figure. Therefore,
The valve body 9a moves to the right in the figure and opens, opening the waist pipe 8. As a result, a part of the exhaust gas flows to the exhaust pipe 3 via the waist pipe 8 without passing through the exhaust turbine 5b, so that the flow rate of the exhaust gas to the turbocharger 5 is adjusted, and the prechamber 6 is pressurized by the turbocharger 5. pressure does not exceed the specified value.

After being pressurized by the turbocharger 5, a part of the air supplied to the pre-chamber 6 is supplied to the exhaust pipe 3 via the secondary air supply path 11 and the check valve 12, and this secondary air Then, carbon monoxide (CO) and hydrocarbons (HC) remaining in the exhaust gas are completely combusted within the exhaust pipe 3. Specifically, when the pressure in the upper chamber 12b of this check valve 12 is higher than the pressure in the lower chamber 12c, that is, when the pressure in the prechamber 6 is higher than the pressure in the exhaust pipe 3, the reed 12e opens. Secondary air is supplied to the exhaust pipe 3 through the hole 12d of the partition wall 12a, and conversely, when the pressure in the lower chamber 12c is higher than the pressure in the upper chamber 12b,
That is, when the pressure in the prechamber 6 is lower than the pressure in the exhaust pipe 3, the reed 12e is closed and exhaust gas does not flow back into the prechamber 6.

The intake pressure in the prechamber 6 is approximately atmospheric pressure or a positive pressure higher than that in all operating ranges such as engine idling, acceleration, cruising, and deceleration.Especially in high-speed operating ranges, the intake pressure of the turbocharger 5 is Due to the pressure, the pressure within the pre-chamber 6 becomes a fairly high positive pressure. Further, the open end 11a of the secondary air supply path 11 is opened near the exhaust port 1d as described above, and the exhaust valve 1c is opened to allow high-speed exhaust from the exhaust port 1d. When the jet flows out, this is the position where a large negative pressure (small pressure in terms of absolute pressure) induced by the exhaust jet is generated, so the differential pressure with the pressure of the pre-chamber 6 is
It can be made larger than other locations in the exhaust pipe 3. Therefore, even when the exhaust pressure in the exhaust pipe 3 is high in the high-speed operating range, an appropriate amount of secondary air can be reliably supplied to the exhaust pipe 3.

In addition, in the above-mentioned embodiment, in order to simplify the explanation,
Although the engine 1 is a single-cylinder engine, similar effects can be obtained even if the present invention is applied to a multi-cylinder engine.

(Effects of the Invention) As described in detail above, the secondary air supply device for an internal combustion engine of the present invention uses the energy of the exhaust gas flowing through the exhaust passage to rotate the turbine and drive the coaxial compressor. a turbocharger that compresses and supercharges the intake air flowing through the intake passage; and a turbocharger that is provided in the middle of the intake passage and temporarily stores the intake air pressurized by the turbocharger to attenuate pressure fluctuations in the intake air flowing within the intake passage. a pre-chamber which changes the flow of air into an air flow having a substantially constant pressure; and a pre-chamber located between the pre-chamber and the compressor of the turbocharger, the pre-chamber is provided in the intake passage and temporarily stores the intake air pressurized by the turbocharger. a resonance chamber that damps pressure vibrations in the intake passage by adjusting the natural frequency of the intake passage between the prechamber and the compressor; and a resonance chamber between the prechamber and the exhaust passage near the exhaust valve. A secondary air supply path constructed by piping connection of is equipped with a differential pressure responsive check valve that closes to prevent backflow of exhaust gas, and supplies secondary air from the pre-chamber to the exhaust passage via the secondary air supply passage and the check valve. This is how it was done.

Therefore, after maintaining the discharge characteristics of the turbocharger and matching the required air amount of the engine,
The intended purpose of exhaust gas purification can be achieved. In particular, the provision of a resonance chamber prevents resonance phenomena in the intake system over the entire operating speed range of the engine, and the provision of a pre-chamber prevents the intake air from flowing due to the opening and closing movements of the intake valve. Pulsations are absorbed and smoothed to form a good intake system airflow, so the surging prevention function is reliably demonstrated, and intake air is supplied without disturbances in flow velocity, resulting in a stable exhaust flow. It will be done. By supplying stable secondary air to the stable exhaust flow in this way, unburned components such as CO and HC can be reburned and removed in the exhaust pipe without the need for a special afterburner. I can,
The structure of the exhaust purification treatment device is simple and its treatment performance is high. Furthermore, since a check valve is installed in the secondary air passage, flashback can be prevented even if the exhaust pressure exceeds the boost pressure.

In addition, since it is sufficient to add a secondary air supply path and a differential pressure-responsive check valve to the conventional device, the structure is simple, inexpensive, durable, and easy to maintain. play.

[Brief explanation of the drawing]

The drawing is a configuration diagram showing an embodiment of an internal combustion engine to which the present invention is applied. DESCRIPTION OF SYMBOLS 1... Engine, 1d... Exhaust port, 2... Intake passage, 3... Exhaust passage, 5... Turbocharger, 6... Pre-chamber, 11... Secondary air supply path, 12... Check valve, 13 ... Resonance chamber.

Claims (1)

[Claims] 1. A turbocharger that compresses and supercharges the intake air flowing through the intake passage by rotating a turbine with the energy of the exhaust gas flowing through the exhaust passage and driving a coaxial compressor, and a turbocharger provided in the middle of the intake passage. a prechamber which temporarily stores intake air pressurized by the intake passageway to attenuate pressure fluctuations in the intake air flowing through the intake passage and converts the intake air into an air flow having a substantially constant pressure; and a compressor for the prechamber and the turbocharger. By temporarily storing the intake air pressurized by the turbocharger, the intake passage is located between the prechamber and the compressor, and adjusts the natural frequency of the intake passage between the pre-chamber and the compressor. a resonance chamber that damps pressure vibrations in the intake passage; a secondary air supply path configured by connecting piping between the pre-chamber and the vicinity of the exhaust valve in the exhaust passage; and a differential pressure-responsive check valve that opens when the pressure in the pre-chamber is higher than the pressure in the exhaust passage and closes when the pressure in the pre-chamber is higher than the pressure in the exhaust passage to prevent backflow of exhaust gas. A secondary air supply device for an internal combustion engine, characterized in that secondary air is supplied from the prechamber to the exhaust passage through the secondary air supply passage and the check valve.