JPS5823489B2 - Exhaust turbocharger output control device for internal combustion engine - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an output control device for preventing excessive output of an exhaust turbocharger installed in an internal combustion engine.

As is well known, an exhaust turbocharger has a structure in which exhaust pressure drives a turbine, and a compressor directly connected to the turbine compresses intake air, converts it into excess air, and sends it to the internal combustion engine.

The internal combustion engine obtains sufficient combustion air from this supercharged air, increasing its output.

With this structure, when the internal combustion engine rotates at high speeds, the exhaust turbocharger also rotates at high speeds due to the increased amount of exhaust gas, resulting in excessive supercharging and excessive output. The exhaust passages of the exhaust gas are connected by a bypass passage, and a bypass valve is provided in the bypass passage.When the boost air pressure in the intake passage downstream of the compressor of the exhaust turbocharger exceeds a set value, the bypass valve is opened and the exhaust is removed. Excessive output is prevented by using an exhaust bypass control device that prevents excessive amounts of supercharging air from the compressor by flowing from the bypass passage to the exhaust passage downstream of the turbine and reducing the exhaust energy acting on the turbine.

However, if only this exhaust bypass control method is used, the excessive output of the exhaust turbocharger compressor is controlled by controlling the amount of exhaust gas that goes to the turbine. Since the engine continues to rotate at a high speed, the amount of supercharged air does not decrease immediately and a time delay occurs.

Therefore, for example, during rapid deceleration at high speeds, or during steady or decelerated driving after rapid acceleration, the reduction in boost pressure cannot be followed in time, causing the internal combustion engine to thrash, over-powering, and eventually causing damage to the pistons and exhaust valves of the internal combustion engine. Otherwise, damage may occur.

There is a way to improve the performance of the bypass valve so that it responds sufficiently even during sudden deceleration, but the bypass valve is generally placed at the upstream side of the bypass passage where it is easily affected by exhaust heat. It is difficult to maintain performance.

If this bypass valve malfunctions, there is a risk that the performance of the main parts of the internal combustion engine will deteriorate.

In addition, if you set the bypass valve opening pressure to a low value from a safe perspective, anticipating a delay in the response of reducing the excessive rise in turbine speed when the bypass valve is opened, you can make the most of the supercharging effect of the compressor. It was something that would disappear.

This invention aims to improve the malfunction of the output control device caused by the exhaust bypass control method of an exhaust turbocharger for an internal combustion engine, and also to prevent an increase in supercharging pressure and engine damage when the exhaust bypass valve malfunctions. and the compressor downstream intake passage through a relief passage equipped with an on-off valve, and when the boost air pressure in the intake passage downstream of the compressor exceeds a set value, the on-off valve is opened and the IJ-F passage is connected to the compressor downstream intake passage. By flowing the supercharged air and returning it to the intake passage upstream of the compressor or releasing it to the atmosphere, the amount of supercharged air going to the internal combustion engine can be immediately reduced.

In this case, the set pressure is set higher than the valve opening set pressure of the exhaust bypass valve.

The present invention will be described below with reference to embodiments shown in the drawings.

In FIG. 1, 1 is an upstream intake passage.

2 is an exhaust turbocharger, which has a structure in which a compressor 3 and a turbine 9 are directly connected through a shaft 10.

The compressor 3 has an inlet part 3' and an outlet part 3'', and the turbine 9 has an inlet part 9' and an outlet part 9''.

An air cleaner 15 and an air flow meter 16 are connected to one end of the upstream intake passage 1, and an inlet portion 3' of a compressor 3 of an exhaust turbocharger 2 is connected to the other end.

An outlet section 3'' of the compressor 3 is connected to a downstream intake passage 4.

5 is a throttle valve, which is provided near the outlet side of the downstream intake passage 4.

The downstream intake passage 4 is connected to an intake manifold 6 fixed to the main body of the internal combustion engine 7.

20 is a fuel injection valve, which is attached to the intake manifold 6.

One end of an upstream exhaust passage 11 is connected to an exhaust manifold 8 fixed to the body of the internal combustion engine 7, and the other end is connected to an inlet portion 9' of a turbine 9.

A downstream exhaust passage 12 is connected to the outlet section 9'' of the turbine 9.

Furthermore, the upstream exhaust passage 11 and the downstream exhaust passage 12 are
They communicate through a bypass passage 14, and the bypass passage 14 includes a bypass valve 13, which controls the opening and closing of exhaust gas passing through the bypass passage 14.

The bypass valve 13 is controlled by the supercharging air pressure on the upstream side of a throttle valve 5 provided near the outlet side of the downstream intake passage 4.

The reason why it is not placed downstream of the throttle valve is that if a diaphragm is used for the valve 13, it would be expensive to make the diaphragm of a material that can receive both positive and negative pressures, which would pose problems in terms of durability. This is because there is a pressure difference and there is a problem with operability before and after the exhaust bypass, so it is necessary to send the bypass valve signal upstream of the throttle valve.

As mentioned above, if the bypass valve is controlled by the boost pressure upstream of the throttle valve, the response during sudden deceleration will be poor due to the inertia of the exhaust turbine, and if emergency measures are not taken if the bypass valve breaks, engine failure will occur. It is as follows.

Therefore, the present invention is configured as follows.

That is, 18 is a relief passage, which communicates the upstream side intake passage 1 with the downstream side intake passage 4 on the upstream side of the throttle valve.

A one-way valve 19, which is a type of on-off valve, is provided at the connection between the relief passage 18 and the upstream intake passage 1.

The one-way valve 19 has the same part as the control pressure of the exhaust bypass valve, that is, the supercharging air pressure in the IJ-F passage 18 is the set value (3
80WHg is suitable and exhaust bypass control pressure is 350MH
When the pressure exceeds (a little higher than g), the valve opens at this pressure and the supercharged air is returned to the upstream intake passage 1.

The details of the one-way valve 19 as a type of on-off valve are shown in FIG.
It is shown in Figure 3.

The casing 19a of the one-way valve 19 is connected to the IJ IJ-
A cylindrical body 21 is fitted into the open end of the air passage 18 and has an opening 21a through which supercharged air passes at the fit-in end, and an annular seal member is provided at the other open end of the cylindrical body 21. It consists of a pipe joint 23 whose one end is connected by caulking via 22,
A male thread 23a formed on the outer circumferential surface of the other end of the pipe joint 23 is formed to penetrate through the wall constituting the upstream intake passage 1, and is screwed into the female thread for connection.

An annular valve seat 24 made of a sealing material such as fluororubber is fixed to the opening 21a of the cylindrical body 21.
A flat plate-shaped valve body 25 disposed opposite to the receiving seat 2 has a peripheral edge 26 a sandwiched between the cylindrical body 21 and the pipe joint 23 .
A compression coil spring 27 interposed between 6 and this valve body 25
As a result, it is urged to come into pressure contact with the end surface of the valve seat 24 and close the opening 21a.

As shown in FIG. 3, the valve body 25 has a plurality of notches 25a on its periphery, and when the valve body 25 moves to the left in FIG. Supercharged air can flow into the cylindrical body 21 through the notch 25a of 25.

The peripheral portion of the valve body 25 other than the notch 25a has an appropriate gap (0,1 to 0,511111) with the inner wall of the cylindrical body 21.
).

The center portion of the seat 26 protrudes toward the valve body 25, and a stopper 28 made of an elastic material such as rubber is fixed to the protruding end, and this stopper 28 regulates the maximum movement position of the valve body 25 when the valve is opened. It is supposed to be done.

In addition, a plurality of communication holes 29 are bored in the peripheral edge 26a of the catch seat 26, and these communicate with each other between the inside of the cylindrical body 21 and the pipe joint 2.
The supercharged air that has entered the cylindrical body 21 can flow to the upstream intake passage via the pipe joint.

Since the valve body 25 is plate-shaped, unlike a diaphragm, there is no problem in terms of durability even if it receives both positive and negative pressure.

Next, the operation will be explained.

Exhaust gas discharged from the main body of the internal combustion engine 7 to the exhaust manifold 8 passes through the upstream exhaust passage 11, enters the inlet part 9' of the turbine 9, rotates the turbine 9, and then flows to the outlet part 9''.
from there to the downstream exhaust passage 12.

The rotation of the turbine 9 at this time causes the compressor 3 directly connected to the shaft 10 to rotate.

By the rotation of compressor 3, air cleaner 1
5. Compress the air that has passed through the air flow meter 16 and the upstream intake passage 1 to the inlet section 3' of the compressor 3,
It is forced to the outlet section 3''.

The pressurized supercharging hollow enters the downstream intake passage 4, and after its flow rate is adjusted by a butterfly type throttle valve 5, it passes through the intake manifold 6 and enters the internal combustion engine 7.

In the internal combustion engine T, the supercharged air mixes well with the gasoline injected from the fuel injection valve 20 into the intake manifold 6, and combustion occurs sufficiently.

Since the air is supercharged air from the exhaust turbocharger 2, there is a sufficient amount of air, so there is little chance of unburned combustion.

Next, when the engine speed increases and a large amount of exhaust gas comes out, the turbine speed increases by 90 rpm due to the exhaust gas. A large amount of supercharging air enters the engine, resulting in excessive supercharging.

Therefore, when the supercharging pressure on the upstream side of the throttle valve 5 in the downstream side intake passage 4 exceeds a set value (for example, 350 MHN), that pressure is transmitted from the pipe 17 to the bypass valve 13.
It is designed to open.

When the bypass valve 13 opens, the exhaust gas escapes through the bypass passage 14, which does not have a turbine serving as a resistor, so that the increase in rotation of the turbine 9 is suppressed, and at the same time, the increase in the rotation of the compressor 30 is also suppressed. The amount of supercharging air decreases, and eventually the power of the internal combustion engine 7 no longer increases excessively.

However, even if the bypass valve 13 is opened and the exhaust gas is released to the bypass passage 14, the rotation of the turbine does not slow down immediately, and the rotation due to inertia continues for a while, and then the rotation of the turbine gradually slows down, resulting in poor responsiveness. It is too late to reduce the amount of supercharged air.

Therefore, even if the compressor 3 continues to supercharge, if the boost pressure on the upstream side of the throttle valve 5 in the downstream intake passage 4 rises to a set value or higher (for example, 38 (ltl!HN)), the The bypass valve 13 is further opened, and the one-way valve 1 is opened further.
9 valve body 25 is pushed open against the compression coil spring 27,
The supercharged air is immediately released to the upstream intake passage 1 through the relief passage 18, so that excessive supercharging can be sufficiently avoided and adjusted.

The opening pressure of the one-way valve 19 is set higher than the opening pressure of the bypass valve 13 because the one-way valve 19 prevents excessive rise during supercharging due to a delay in the response of the turbine after the bypass valve 13 is opened. Therefore, there is an advantage that the opening pressure of the bypass valve 13 can be set sufficiently large to make maximum use of the supercharging action of the third compressor.

If the opening pressure of the one-way valve 19 is set equal to the opening pressure of the bypass valve 13, this will prevent the supercharging pressure from rising excessively, but due to the inertia of the turbine 9 after the bypass valve 13 is opened, Due to the overspeed and the reduction in load on the compressor 3 due to the opening of the one-way valve 19, the rotational speed of the turbine and compressor increases considerably, leading to damage to the turbocharger.

Also, if there is no one-way valve 19 and relief passage 18,
It is necessary to set the opening pressure of the bypass valve 13 sufficiently low to prevent the boost pressure from rising above a safe value even if there is overspeed due to inertia of the turbine 9 after the bypass valve 13 is opened. , the supercharging effect of the combustor cannot be utilized to the fullest.

Furthermore, in this embodiment, by installing the one-way valve 19 on the side of the compressor inlet 3' in the relief passage 18, the one-way valve 19 is constantly cooled with low-temperature intake air, and the temperature of the valve does not rise. This prevents valve deterioration.

Furthermore, the supercharged air may be configured to flow from the relief passage to the atmosphere via an on-off valve.

In this case, the sound emitted has the effect of notifying the driver of an abnormality.

As mentioned above, the bypass valve performs the function of constantly adjusting the amount of supercharged air so that it does not increase beyond a certain value, and the one-way valve is used when there is a sudden or abnormal increase in the amount of supercharged air that cannot be responded to by the bypass valve. Instead of compensating for this, both valves reduce the boost pressure, so the amount of boost air can always be maintained at an appropriate level.

Further, when the exhaust bypass valve fails, an increase in overpressure occurs, but the engine is not supercharged beyond the setting of the on-off valve provided in the IJ-F passage, thereby preventing damage to the engine.

By the action of these two valves, it is possible to sufficiently prevent damage to various parts of the engine due to an excessive increase in engine power or a sudden or abnormal increase in supercharging pressure.

In addition, since the opening pressure of the on-off valve is set higher than the opening pressure of the bypass valve, the opening pressure of the bypass valve can be set sufficiently large to maximize the supercharging effect of the turbocharger.
Engine output or engine efficiency can be improved.

[Brief explanation of drawings]

FIG. 1 is a schematic diagram of an internal combustion engine equipped with an exhaust turbocharger according to the present invention, and FIGS. 2 and 3 are diagrams showing the structure of a one-way valve according to the present invention. 1...Upstream intake passage, 2...Exhaust turbocharger, 13...Bypass valve, 14
...Bypass passage, 18...IJ I
J-fu passage, 19... one-way valve.

Claims (1)

[Claims] 1 The exhaust passages upstream and downstream of the turbine of the exhaust turbocharger are connected by a bypass passage equipped with a bypass valve, and when the supercharging air pressure in the intake passage downstream of the compressor of the exhaust turbocharger exceeds a set value, the above-mentioned It is equipped with an exhaust bypass device that opens the bypass valve and allows exhaust gas to flow through the bypass passage, and also connects a relief passage with an on-off valve to the intake passage downstream of the compressor, so that the supercharged air pressure in the intake passage downstream of the compressor is set at a set value. A supercharged air IJ leaf device is provided which opens the on-off valve and allows supercharged air to flow through the relief passage when the above condition occurs, and the set pressure for opening of the on-off valve is set higher than the set pressure for opening of the bypass valve. This is an output control device for an exhaust turbocharger for internal combustion engines.