JPH08200082A - Overspeed preventive device of turbocharger - Google Patents

Abstract

PURPOSE: To prevent the deterioration of drivability just after actuation when outside air pressure is low without complicating control in an overspeed preventive device of a turbocharger. CONSTITUTION: An overspeed preventive device is provided with a turbocharger 5 having a compressor 5a arranged in an intake air passage 2 and a turbine 5b arranged in an exhaust air passage 4, a fluid outflow port 2b formed at least in one of the compressor downstream of the intake air passage 2 and the turbine upstream of the exhaust air passage 4, a closing valve 11 to close the fluid outflow port 2b and a detecting means 21 to detect that the turbocharger 5 exists in an overspeed area, and is provided with closing valve opening means 10 and 20 to open the closing valve 11 only when the fact that the turbocharger 5 exists in an overspeed area is detected by the detecting means 21 and a sonic nozzle 12 installed in the fluid outflow port 2b.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a turbocharger over-rotation preventing device used for supercharging an internal combustion engine.

[0002]

2. Description of the Related Art In the case where an internal combustion engine having a turbocharger is mounted on an aircraft, the external pressure becomes low when the flight altitude of the aircraft becomes high. Requires the turbocharger to rotate at a very high speed, which can cause the turbocharger to overrun, i.e., overspeed and be damaged. Even when an internal combustion engine having a turbocharger is mounted on a vehicle, such an over-rotation of the turbocharger is caused by the difference in the external pressure between the highland and the lowland, and the set supercharging during the highland driving is similar to that in the lowland traveling. It can occur when trying to achieve pressure.

In Japanese Patent Laid-Open No. 2-163419, in a supercharging pressure control device generally provided in an internal combustion engine having a turbocharger, the target supercharging pressure is set to be lower as the atmospheric pressure is lower. Describes that the turbocharger is prevented from over-rotating.

If such a supercharging pressure control device functions normally, it is possible to prevent the turbocharger from over-rotating without any particular problem, but the turbocharger over-rotating may damage it. Because it must be reliably prevented, it is not possible to rely on it only for the supercharging pressure control device that uses a step motor or the like to perform duty control on the wastegate valve in a complicated manner. Further, it is common to provide a highly reliable independent over-rotation preventing device.

Such an over-rotation preventing device for a turbocharger is generally a closing valve for closing an opening to the outside air provided in the intake passage, and this closing valve is a turbocharger using a rotation sensor or the like. When the over-rotation of the engine is detected, the valve is opened to open the opening, so that a part of the intake air is discharged to the outside air and the flow rate of the intake air flowing into the cylinder is reduced. As a result, it is provided to the turbocharger. By reducing the exhaust gas pressure, the rotation of the turbocharger is reduced to the normal rotation range, and then the closing valve is closed and the opening is closed again.

[0006]

In such an overspeed preventive device, the time from the opening of the closing valve to the closing of the closing valve has a time delay until the turbocharger actually reaches the normal rotation range. Since it is included, it becomes relatively long, and especially when the external air pressure is low and the pressure difference from the supercharging pressure is large, the intake flow rate flowing out from the opening during this period becomes very large, and the turbocharger is in the normal rotation range. When the closing valve is closed, the boost pressure is considerably low,
There is a problem that the engine output is significantly reduced and drivability is considerably deteriorated as compared with before the operation of the over-rotation preventing device.

In order to solve this problem, it is possible to make the opening area of the opening relatively small so that the intake flow rate flowing out from the opening becomes an appropriate value for a large differential pressure. When it is small, the flow rate of the intake air flowing out from the opening becomes considerably small, which extends the time until the excessive rotation of the turbocharger is suppressed, which is not practical. Further, duty control of the closing valve is considered, but not only the drive system and the control system for that cause a considerable increase in cost, but also complicating the control system in this way reduces reliability. . Therefore, an object of the present invention is to provide a turbocharger over-rotation preventing device capable of preventing deterioration of drivability immediately after the operation when the external pressure is low without complicating the control.

[0008]

A turbocharger over-rotation preventing device according to a first aspect of the present invention is a turbocharger having a compressor arranged in an intake passage and a turbine arranged in an exhaust passage, and an intake passage. A fluid outlet formed on at least one of the compressor downstream side and the turbine upstream side of an exhaust passage, a closing valve that closes the fluid outlet, and detection that detects that the turbocharger is in the over-rotation region. Means, a closing valve opening means for opening the closing valve only when the detection means detects that the turbocharger is in an over-rotation range, and a sonic nozzle attached to the fluid outlet. It is characterized by including.

According to a second aspect of the present invention, there is provided a turbocharger over-rotation preventing device according to the first aspect of the present invention, wherein the turbocharger over-rotation preventing device is provided in the passage in which the fluid outlet is formed. It is characterized by further comprising valve opening preventing means for preventing the closing valve opening means from opening the closing valve when the pressure difference between the open air and the outside air is equal to or lower than a predetermined pressure.

[0010]

In the turbocharger over-rotation preventing device according to the first aspect, the closing valve opening means opens the closing valve only when the detecting means detects that the turbocharger is in the over-rotation range. Since the fluid outlet formed in at least one of the downstream side of the compressor in the intake passage and the upstream side of the turbine in the exhaust passage is opened, the exhaust gas pressure provided to the turbine of the turbocharger is reduced and the turbocharger is reduced. Becomes the normal rotation range, at which time the fluid outlet is closed again by the closing valve. The flow velocity of the fluid flowing out from the fluid outlet by the sonic nozzle attached to the fluid outlet even when the external pressure is low and the pressure difference in the passage where the fluid outlet is formed is very large while the closing valve is open. Is suppressed to the sonic speed, the outflow flow rate does not exceed the flow rate at the sonic speed, and the engine output immediately after the operation does not significantly decrease compared to immediately before the operation of the overspeed prevention device.

The turbocharger over-rotation preventing device according to claim 2 is the turbocharger over-rotation preventing device according to claim 1 in which the valve opening preventing means forms the fluid outlet. In order to prevent the closing valve from being opened by the closing valve opening means when the pressure difference between the inside of the passage and the outside air is equal to or lower than the predetermined pressure, the closing valve is not opened when the atmospheric pressure is relatively high. Absent.

[0012]

1 is a schematic cross-sectional view of an internal combustion engine for an aircraft equipped with a turbocharger over-rotation preventing device according to a first embodiment of the present invention. Reference numeral 1 is an internal combustion engine, 2 is an intake passage communicating with the internal combustion engine through a throttle valve 3, and 4 is an exhaust passage. A compressor 5a of a turbocharger 5 is arranged upstream of the throttle valve 3 in the intake passage 2, and a turbine 5b thereof is arranged in the exhaust passage 4. Intake passage 2
The upstream side of the compressor 5a is open to the atmosphere via an air cleaner (not shown).
An intercooler 6 for cooling the intake air supplied to the internal combustion engine 1 is arranged between the throttle valve 3 and the throttle valve 3.

A downstream side of the turbine 5b of the exhaust passage 4 is open to the atmosphere via a catalytic converter (not shown), and a bypass passage 4a is formed to bypass the turbine 5b and communicate with the catalytic converter. A wastegate valve 7 is arranged in the bypass passage 4a. As is generally known, the wastegate valve 7 is duty-controlled by a step motor (not shown) or the like, and is connected to the turbine 5b so that the target boost pressure in the current engine operating state is realized. It regulates the exhaust gas pressure provided.

Between the throttle valve 3 of the intake passage 2 and the intercooler 6, two openings communicating with the atmosphere are formed, and the first opening 2a thereof opposes the pressure in the intake passage 2. It is closed by a first closing valve 9 which is biased in a valve closing direction by a first spring member 8 and the like, a sonic nozzle 12 is attached to the second opening 2b, and a second closing is driven by a driving device 10. It is closed by the valve 11.

The first spring member 8 has an upper limit value, for example, 133 kPa (1000 mmHg), which is set so that the supercharging pressure in the intake passage 2 by the compressor 5a of the turbocharger 5 does not damage the internal combustion engine as the output increases. The spring constant of the first closing valve 9 is selected so that it is opened by this pressure when the pressure receiving area of the first closing valve 9 is taken into consideration. The upper limit value of is controlled. Further, a bellows 22 having a vacuum inside is attached to the back surface side of the first closing valve 9, so that when the first closing valve 9 is opened, the bellows 22 is less susceptible to the atmospheric pressure acting thereon. Has become.

Further, the second closing valve 11 is for preventing the turbocharger 5 from over-rotating which causes damage to the turbocharger 5, and the drive device 10 of the second closing valve 11 has the second closing valve 11 fixed. The first chamber 10 communicating with the outside air is provided with the diaphragm 10a and the second spring member 10b for urging the second closing valve 11 in the closing direction via the diaphragm 10a.
c, a second chamber 10d formed on the opposite side of the first chamber 10c with the diaphragm 10a as a boundary, and a switching valve 10e for communicating the second chamber 10d with the inside of the intake passage 2 or one of the outside air. . This switching valve 10e is designed to normally communicate the second chamber 10d with the outside air, whereby the outside air pressure acts on both sides of the diaphragm 10a and these forces cancel each other out. Has
Further, since the second spring member 10b exerts an urging force in the valve closing direction of the second closing valve 11, the second closing valve 11 is closed and the second opening 2b is closed.

20 is the waste gate valve 7 described above.
Is a control device that controls the opening / closing of the second closing valve 11 by switching the switching valve 10e of the drive device 10 while being in charge of the duty control of the engine 10. Each sensor for detecting the engine operating state, for example, the engine speed is detected. An engine rotation sensor for detecting the engine speed, a throttle opening sensor for detecting a throttle opening as an engine load, and the like are connected, and a turbocharger rotation sensor 21 for detecting the rotation speed of the turbocharger 5 is connected. .

In the duty control of the waste gate valve 7 by the control device 20, the target supercharging pressure for each engine operating state is set to the above-mentioned upper limit value or lower in consideration of the external atmospheric pressure and becomes lower. Therefore, the first closing valve 9 and the second closing valve 11 will not operate if this duty control is realized as intended, but for example, in the actual operation, If the duty ratio is not realized as instructed, the boost pressure may exceed the upper limit value, or the turbocharger 5 may be in the overspeed range. This is for surely preventing damage to the internal combustion engine 1 and the turbocharger 5.

The opening / closing control of the second closing valve 11 via the drive unit 10 by the control unit 20 causes the turbocharger 5 detected by the turbocharger rotation sensor 21 to be in the over-rotation region when the rotational speed of the turbocharger 5 exceeds a predetermined rotational speed. The switching valve 10e of the drive device 10 is switched so that the second chamber 10d communicates with the inside of the intake passage 2 only when it is set. As a result, the supercharging pressure in the intake passage 2 is provided to the second chamber 10d, and the supercharging pressure when the turbocharger 5 is in the overspeed range is considerably high.
The diaphragm 10a is pressed in the valve opening direction of the second closing valve 11 against the external air pressure acting on the opposite side to the biasing force of the second spring member 10b, and the second closing valve 11 is opened.

When the second closing valve 11 is opened, the second opening 2b is opened and a part of the supercharged intake air is supplied to the second opening 2b.
The flow rate of intake air supplied to the internal combustion engine 1 in order to flow to the outside air side from b is reduced, whereby the flow rate of exhaust gas discharged from the internal combustion engine 1 is reduced and the exhaust pressure provided to the turbine of the turbocharger 5 is reduced. Is reduced, and the rotation speed of the turbocharger 5 can be reduced to the normal rotation range. When the turbocharger rotation sensor 21 detects that the rotation of the turbocharger 5 has reached the normal rotation range,
The switching valve 10e of the drive device 10 is switched again to the atmospheric pressure side, the second closing valve 11 is closed, and the second opening 2b is closed.

In the prevention of excessive rotation of the turbocharger 5 as described above, the rotational speed of the turbocharger 5 in the overspeed region is actually normal during the time from the opening of the second closing valve 11 to the closing thereof. Since it is the time until the rotational range is reached, the time until the inertial force of the turbocharger 5 declines is added to the time until the exhaust pressure provided to the turbocharger 5 actually decreases, which is relatively long. As a result, the intake flow rate flowing out from the second opening 2b becomes a value according to the pressure difference between the external atmospheric pressure and the supercharging pressure during this period, so that the supercharging pressure can be reduced immediately before the opening of the second closing valve 11. Compared to, the engine output immediately after closing the valve decreases.

FIG. 2 is a graph showing this engine output reduction amount with respect to the flight altitude. The solid line is for this embodiment and the dotted line is for the conventional example. In both cases, when the flight altitude is relatively low, the engine output reduction amount is zero, which means that the external pressure at this time is relatively high and the desired supercharging pressure is achieved without the rotational speed of the turbocharger 5 increasing so much. To be done
This is because the turbocharger 5 does not enter the overspeed range and the second closing valve 11 is not opened.

In the drive device 10 for the second closing valve 11 in the present embodiment, the spring constant of the second spring member 10b is the external pressure when the flight altitude is relatively low, for example, 73.2 kPa.
When the external pressure of (550 mmHg) or more is provided to the first chamber 10c, the upper limit boost pressure 133 kPa is supplied to the second chamber 10d.
The second closing valve 11 is selected so as not to open even when (1000 mmHg) is provided, so that the turbocharger 5 is in the over-rotation range when the flight altitude of the aircraft is relatively low for some reason. Even if the switching valve 10e of the drive unit 10 is switched to the intake passage 2 side due to the erroneous determination that the second closing valve 11 is not opened, an unnecessary reduction in engine output is prevented. .

When the flight altitude is further increased, the external pressure becomes relatively low, and the turbocharger 5 may be in the over-rotation range. When the over-rotation preventing device operates, the supercharging pressure decreases as the external pressure decreases. And the flow rate of intake air flowing out from the second opening 2b increases, and the second closing valve 1
In both the present embodiment and the conventional example, the engine output reduction amount when the valve 1 is closed increases as the flight altitude increases until the flow velocity of the intake air flowing out from the second opening 2b reaches the sonic velocity.

Even if the atmospheric pressure decreases until the flight altitude reaches the predetermined altitude H1 and the flow velocity of the intake air flowing out from the second opening 2b reaches the sonic speed, in the conventional example, the second opening increases as the flight altitude further increases. Since the intake air flow velocity flowing out of the portion 2b is accelerated and the outflow flow amount is increased, the engine output reduction amount when the second closing valve 11 is closed is further increased. On the other hand, in this embodiment, since the sonic nozzle 12 is attached to the second opening 2b, even if the flight altitude exceeds the predetermined altitude H1, the intake flow velocity flowing out from the opening 2b is suppressed to the sonic velocity. Since the intake flow rate at the time of sound velocity is prevented from becoming higher than the intake flow rate, the engine output reduction amount when the second closing valve 11 is closed does not increase above the value at the predetermined altitude H1, and the engine speed decreases. It is possible to prevent the engine output immediately after the operation from being significantly reduced as compared to immediately before the operation of the protective device.

FIG. 3 is a schematic sectional view of an internal combustion engine for an aircraft equipped with a turbocharger over-rotation preventing device according to a second embodiment of the present invention. Only the differences from the first embodiment will be described below. In the present embodiment, the second opening 4b ′ closed by the second closing valve 11 ′ is formed not on the intake passage 2 but on the upstream side of the branch portion of the bypass passage 4a of the exhaust passage 4. The connection pipe 13 is connected to the second opening 4b 'through a sonic nozzle 12', and the second opening 4b 'is opened when the second closing valve 11' is opened.
The exhaust gas flowing out from b'is guided to the catalytic converter by this connecting pipe 13.

The second closing valve 11 'for closing the second opening 4b' is driven by the driving device 10 'which utilizes the differential pressure between the external pressure and the supercharging pressure as in the first embodiment. The control device 20 'controls opening / closing similarly to the first embodiment. When the second closing valve 11 ′ is opened while the turbocharger 5 is in the overspeed range, a part of the exhaust gas is supplied to the turbine 5b of the turbocharger 5 in order to flow out from the second opening 4b ′. The exhaust gas pressure generated is reduced, and the rotational speed of the turbocharger 5 can be reduced to the normal rotational range as in the first embodiment.

Since the sonic nozzle 12 'is attached to the second opening 4b' when the exhaust gas flows out, even if the flight altitude is considerably high and the external pressure is extremely low, the exhaust gas The outflow velocity is suppressed to the speed of sound,
Since the outflow rate does not exceed the flow rate at this sound speed,
When the second closing valve 11 'is closed, the exhaust gas pressure is too low to perform sufficient supercharging by the turbocharger 5, and the engine output is increased immediately after the operation just before the operation of the over-rotation preventing device. It is prevented from dropping significantly.

In the two embodiments, the drive device for driving the second closing valve is not limited to the one that uses the differential pressure between the supercharging pressure and the atmospheric pressure, but uses other forces such as hydraulic pressure and electromagnetic force. It may be one that does.

[0030]

As described above, according to the overcharge preventing device for a turbocharger according to the first aspect of the present invention, the closing valve is opened only when the detecting means detects that the turbocharger is in the overspeed range. The exhaust provided to the turbine of the turbocharger for opening the fluid outlet formed on at least one of the intake passage downstream of the compressor and the exhaust passage upstream of the turbine by the valve means opening the closing valve. The gas pressure is reduced and the turbocharger enters the normal rotation range. The flow velocity of the fluid flowing out from the fluid outlet by the sonic nozzle attached to the fluid outlet even when the external pressure is low and the pressure difference in the passage where the fluid outlet is formed is very large while the closing valve is open. Is suppressed to the speed of sound, and the outflow flow rate does not exceed the flow rate at the time of sound speed, and the engine output immediately after the operation does not significantly decrease compared to immediately before the operation of this over-rotation prevention device. Can be prevented from worsening.

According to a second aspect of the present invention, there is provided the turbocharger over-rotation preventing device according to the first aspect of the present invention, wherein the turbocharger over-rotation preventing device according to the first aspect is characterized in that When the differential pressure between the inside of the passage where the outlet is formed and the outside air is less than or equal to the predetermined pressure, the atmospheric pressure is relatively high to prevent the closing valve from being opened by the closing valve opening means, and the turbocharger is excessively rotated. If not, the closing valve will not be opened even if the detecting means erroneously determines that the turbocharger is excessively rotating, and it is possible to prevent an unnecessary reduction in engine output.

[Brief description of drawings]

FIG. 1 is a schematic cross-sectional view of an internal combustion engine equipped with a turbocharger over-rotation preventing device according to a first embodiment of the present invention.

FIG. 2 is a graph showing the engine output reduction amount immediately after the operation of the over-rotation preventing device with respect to the flight altitude.

FIG. 3 is a schematic cross-sectional view of an internal combustion engine equipped with a turbocharger over-rotation preventing device according to a second embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Internal combustion engine 2 ... Intake passage 4 ... Exhaust passage 5 ... Turbocharger 7 ... Wastegate valve 9 ... First closing valve 10, 10 '... Drive device 11, 11' ... Second closing valve 12, 12 '... Sonic nozzle 20, 20 '... Control device 21 ... Turbocharger rotation sensor

Claims (2)

[Claims] 1. A turbocharger having a compressor arranged in an intake passage and a turbine arranged in an exhaust passage, and a fluid flow formed in at least one of the compressor downstream side of the intake passage and the turbine upstream side of the exhaust passage. An outlet, a closing valve that closes the fluid outlet, a detection unit that detects that the turbocharger is in the overspeed range, and a detection unit that detects that the turbocharger is in the overspeed range. A turbocharger over-rotation prevention device comprising: a closing valve opening means for opening the closing valve only occasionally; and a sonic nozzle attached to the fluid outlet. 2. A valve opening prevention means for preventing the closing valve opening means from opening the closing valve when the pressure difference between the inside of the passage in which the fluid outlet is formed and the outside air is not more than a predetermined pressure. The turbocharger over-rotation preventing device according to claim 1, further comprising: