JPS6233959Y2 - - Google Patents

Description

[Detailed description of the invention] [Technical field of the invention] The invention relates to an internal combustion engine with an exhaust turbo supercharger,
In particular, an exhaust turbo supercharger that prevents lubricating oil from leaking from the bearing part to the intake system side, which is in a negative pressure state, when the exhaust gas is detoured from the turbine to create a non-supercharging state during low-load operation of the internal combustion engine. The invention relates to an internal combustion engine equipped with a

[Technical background of the invention and its problems]

In general, in a diesel engine, the amount of air taken into the cylinder is approximately constant during both low-load and high-load operation, and its output is controlled by the fuel injection amount. Therefore, conversely, the maximum output of the engine is determined based on the fact that the amount of fuel that can be combusted is limited by the amount of air that can be taken in.

On the other hand, an exhaust turbo supercharger mainly includes a compressor provided in the intake system of an internal combustion engine, a turbine provided in the exhaust system, and a drive shaft that connects these turbines and the compressor to drive them coaxially.
A turbine driven by exhaust gas drives a compressor via the drive shaft, pressurizes intake air, and supplies it to the internal combustion engine (supercharging). have.

Installing such an exhaust turbo supercharger in the intake/exhaust system of a diesel engine to perform supercharging,
By increasing the amount of air filled into the cylinder using the energy of the exhaust gas and adding fuel that can be combusted by the increased amount, it is possible to improve the output of the engine.

However, in a diesel engine in a low/medium load operating range, the amount of air is excessive compared to the amount of fuel injected. For this reason, such low
Supercharging in a medium load operating range will only unnecessarily increase friction and worsen fuel efficiency.

Considering these characteristics of diesel engines, conventionally, during low to medium load operation, the exhaust gas of the internal combustion engine is bypassed from the turbine and the compressor function is canceled to stop the entire function of the exhaust turbo supercharger, and the function of the compressor is canceled. It is known that the engine is operated by drawing air only by the suction force of the piston. However, in such a non-supercharging state, the entire intake system including the area around the compressor is placed in a large negative pressure state due to the intake action of the internal combustion engine, while the area around the turbine in the exhaust system is Due to the exhaust pressure of the engine, the pressure is relatively higher than atmospheric pressure, which creates a pressure difference in the bearings located between the turbine and the compressor, and a large negative pressure suction force acts from the intake system side. It turns out. The inside of this bearing is filled with lubricating oil supplied to lubricate the drive shaft, and a strong seal is applied to prevent oil leakage. There was a problem in that the lubricating oil leaked to the intake system side due to the pressure suction force and the above-mentioned pressure difference. In order to deal with this, it is possible to adjust the amount of oil supplied during non-supercharging, but simply stopping the supply of oil means that even when the compressor is cancelled, the drive shaft is rotated by the turbine that receives a small amount of exhaust gas. On the other hand, if oil is supplied continuously even in a small amount, there is a possibility of oil leakage, and a complicated oil supply adjustment device is required as it may cause seizing of the bearing when transitioning to supercharging operation where the rotation speed increases instantly. It was difficult to do so.

In addition, if the exhaust turbo supercharger is completely stopped to achieve a non-supercharging state, even if the internal combustion engine shifts to high-load operation and attempts to supercharge instantly,
There was a problem in that the rotation of the compressor did not increase immediately and its starting response deteriorated, making it impossible to obtain a smooth increase in output. Furthermore, when there is no supercharging in which intake air is bypassed from the compressor, the compressor is in a no-load state, so there is a risk that the exhaust turbo supercharger will overrun and cause surging. As a related technology, "supercharging engine"
No. 2) has been proposed.

[Purpose of invention]

The present invention has been developed in view of the conventional problems as mentioned above.
It was devised to solve these problems all at once and effectively.

The purpose of this invention is to prevent lubricating oil from leaking from the bearing part into the intake system, which is in a negative pressure state, when the internal combustion engine is operated at low to medium loads and the exhaust gas is detoured from the turbine to create a non-supercharging state. It can be prevented and
An object of the present invention is to provide an internal combustion engine with an exhaust turbo supercharger that can prevent compressor surging.

[Example of idea]

Hereinafter, a preferred embodiment of an internal combustion engine with an exhaust turbo supercharger according to the present invention will be described in detail with reference to the accompanying drawings.

As shown in FIG. 1, 1 is an internal combustion engine, and a cylinder 2 thereof is connected to an intake system 5 and an exhaust system 6 via an intake valve 3 and an exhaust valve 4. As shown in FIG. The intake system 5 and the exhaust system 6 are provided with an exhaust turbo supercharger 7 for connecting them and imparting exhaust energy to the intake air. Specifically, this exhaust turbo supercharger 7 mainly includes a turbine 8 provided in the middle of the exhaust system 6, a compressor 9 provided in the middle of the intake system 5, and the compressor 9 and the turbine 8. It is comprised of a drive shaft 10 that is connected to drive coaxially, and a bearing part 11 that bears this drive shaft 10. The exhaust turbo supercharger 7 is connected to the exhaust system 6 during high-load operation of the internal combustion engine 1.
A turbine 8 driven by exhaust gas flowing through the intake system 5 coaxially drives a compressor 9 to pressurize intake air flowing through the intake system 5 and supply it to the internal combustion engine 1 (supercharging). Further, the bearing portion 11 of the exhaust turbo supercharger 7 has a drive shaft 1 inside thereof.
The compressor 9 and turbine 8 sides of this bearing section 11 are filled with lubricating oil to lubricate the intake system 5 and exhaust system 6.
A seal is applied to prevent leakage to the outside.

By the way, as shown in the figure, the exhaust system 6 includes exhaust gas that is branched upstream of the exhaust gas inlet 8a of the turbine 8 and bypasses the turbine 8 to the downstream side of the exhaust gas outlet 8b of the turbine 8, which is the downstream side of the exhaust system 6. A bypass passage 12 is provided in the other intake system 5, and a bypass passage 12 is provided in the intake system 5.
An intake bypass passage 13 that bypasses the compressor 9 is provided over the b side. Furthermore, these bypass passages 12 and 13 are provided with a first bypass on-off valve 14 and a second bypass on-off valve 15 for opening and closing them in synchronization with each other. and,
During high-load operation of the internal combustion engine 1, these bypass passages 12 and 13 are both closed by the bypass on-off valves 14 and 15, so that all of the exhaust gas is supplied to the turbine 8 and the compressor 9 supercharges all of the intake air to the internal combustion engine 1. It is composed of On the other hand, during low/medium load operation, these bypass passages 12, 13 are both opened by bypass opening/closing valves 14, 15. At this time, the exhaust bypass passage 12 is configured to bypass most of the exhaust gas from the turbine 8 in order to place the exhaust turbo supercharger 7 in a non-supercharging state. In addition, the intake bypass passage 13 is configured to direct intake air to the compressor 9 so that the flow of intake air due to the suction action of the piston 16 of the internal combustion engine 1 is not obstructed by the compressor 9 interposed in the intake system 5 in the non-supercharging state. is configured to be diverted from.
In particular, since the first bypass opening/closing valve 14 opens and closes only the exhaust bypass passage 12 on the upstream side of the exhaust gas inlet 8a of the turbine 8, the turbine Since the 8 side is connected and a part of the exhaust gas is supplied to the turbine 8, the turbine 8 is continuously driven even though the rotation speed is relatively low.

In particular, a discharge port side passage 17 that is formed continuously with the discharge port 9b of the compressor 9 and connected to the downstream side of the intake bypass passage 13 is closed so that the discharge port 9b side of the compressor 9 can be connected to a predetermined position. A gate valve 19 is provided to partition a pressure chamber 18 that is maintained at a positive pressure. This gate valve 19 has
Gate valve opening degree control means 20 is provided to operate this. This gate valve opening control means 20 includes a cylinder 21, a diaphragm 24 that partitions the inside of the cylinder 21 into an atmospheric pressure chamber 22 and a pressure introduction chamber 23,
It has a rod 25 that operates the gate valve 19 by the deflection of the diaphragm 24. Atmospheric pressure is introduced into the atmospheric pressure chamber 22 through a hole 26 formed in the cylinder 21, and a spring 27 is provided that biases the diaphragm 24 toward the pressure introduction chamber 23 side. On the other hand, a compressor 9 is installed in the pressure introduction chamber 23.
A pressure detection pipe 28 is connected to detect the pressure on the discharge port 9b side (inside the pressure chamber 18 when the gate valve 19 is closed). Then, the discharge port 9 of the compressor 9
When the pressure on the b side is low, the gate valve 19 closes the discharge port side passage 17 due to the biasing force of the spring 27, and the pressure detection tube 28 detects that the pressure gradually increases to a predetermined pressure or higher. When the pressure introduced into the pressure introduction chamber 23 is balanced with the spring 27, the diaphragm 24 is bent to operate the gate valve 19, and the pressure on the discharge port 9b side of the compressor 9 is restored to a predetermined pressure. It is configured to control the opening degree of the outlet side passage 17. Therefore, during non-supercharging, the entire intake system 5 including the discharge port 9b side of the compressor 9 is in a negative pressure state, so the discharge port side passage 17 is closed by the gate valve 19 and the pressure chamber 18 is closed. The compressor 9 draws in a part of the intake air sucked into the intake bypass passage 13 side by the turbine 8 driven by a part of the exhaust gas and discharges pressurized air, thereby increasing the pressure in the pressure chamber 18. The discharge port 9b side of the compressor 9 facing this can be brought to a predetermined pressure (positive pressure). Furthermore, when the pressure inside the pressure chamber 18 exceeds a predetermined pressure due to continuously discharged pressure air, the gate valve opening control means 20 detects this and can control the opening of the gate valve 19 to release the pressure. ,
While preventing surging of the compressor 9 due to excessive pressure rise, the discharge port 9 of the compressor 9 is
This means that the b side can be maintained at a predetermined pressure. Further, the spring 27 provided in the gate valve opening control means 20 is
With the pressure ratio of the compressor 9 (=compressor discharge port side pressure/compressor suction port side pressure) set to an appropriate value, the pressure on the exhaust gas inlet 8a side of the turbine 8 (=exhaust pressure of the internal combustion engine) during non-supercharging is determined. Its spring constant is set to reduce friction without increasing it.

The first bypass on-off valve 14 and the second bypass on-off valve 15 are provided with valve actuation means 29 having the same configuration as the gate valve opening degree control means 20 to open and close them respectively. ing.
This valve operating means 29... includes a cylinder 21..., a diaphragm 24... that partitions the inside of this cylinder 21... into an atmospheric pressure chamber 22... and a pressure introduction chamber 23..., and a bypass opening/closing valve 1 by the deflection of this diaphragm 24...
4, 15. Atmospheric pressure is introduced into the atmospheric pressure chambers 22 through holes 26 formed in the cylinders 21, and springs 27 are provided to bias the diaphragms 24 toward the pressure introduction chambers 23. It is being On the other hand, the pressure introduction chambers 23 are connected to the pressure source 31 or the atmosphere via a three-way switching solenoid valve 34. A load detection switch 33 connected to a battery 32 or the like is connected to the electromagnetic valve 34 in order to detect the load condition of the internal combustion engine 1 and excite the electromagnetic valve 34 to switch the load state.

During low/medium load operation of the internal combustion engine 1, this is detected and the load detection switch 33 is opened.
The solenoid valve 34 is not excited and the pressure source 31 and pressure introduction chamber 23
... are communicated with each other, and the diaphragm 24 is bent against the spring 27. Diaphragm 2
4... is bent, the bypass on-off valves 14, 1
5 opens the bypass passages 12 and 13 synchronously. On the other hand, when the load detection switch 33 detects that high-load operation has started, it closes, and the electromagnetic valve 34 is excited and switched, so that the atmosphere and the pressure introduction chambers 23 are communicated with each other.

The operation of the above configuration will be described.

During low/medium load operation of the internal combustion engine 1, it is not desirable to supercharge the intake air to the cylinder 2, so the bypass opening/closing valve 1 is operated by the valve operating means 29.
4 and 15 are activated, both the intake bypass passage 13 and the exhaust bypass passage 12 are opened, intake air and exhaust air are detoured from the exhaust turbo supercharger 7, and the engine is operated in a non-supercharging state. At this time, the intake system 5
Since the pressure is in a negative pressure state, the gate valve 19 closes the discharge port side passage 17 to partition the pressure chamber 18, and at the same time, in the exhaust system 6, a part of the exhaust gas flows into the turbine 8 and It's driving. Therefore, the compressor 9 can operate the turbine 8 even in the non-supercharging state.
This means that a portion of the intake air is sucked in and pressurized air is discharged, thereby increasing the pressure in the pressure chamber 18 and maintaining the pressure on the discharge port 9b side of the compressor 9 at a predetermined pressure (positive pressure). Therefore, due to this pressure chamber 18, the bearing portion 1
1 from the negative pressure suction force of the intake system 5, and it is possible to prevent lubricating oil from leaking into the intake system 5 via the seal.

In addition, since the discharge port 9b side of the compressor 9 is maintained at a positive pressure, the compressor 9 is allowed to perform work based on the pressure difference even when there is no supercharging.
The turbine 8 does not overrun, and the exhaust turbo supercharger 7 can be continuously driven.

Further, since the opening of the gate valve 19 is appropriately controlled by the gate valve opening degree control means 20 that detects the pressure inside the pressure chamber 18, the inside of the pressure chamber 18 can be maintained at a predetermined pressure, and the surging of the compressor 9 can be controlled. In addition, it is possible to reduce friction without increasing the exhaust pressure of the internal combustion engine 1.

Note that during high-load operation of the internal combustion engine 1, the bypass on-off valves 14 and 15 are closed to the bypass passages 12 and 1.
By closing 3, the engine will be operated in a normal supercharging state. At this time, the gate valve 19
is operated by the pressure on the discharge port 9b side of the compressor 9, so when such a compressor 9 has a high discharge pressure, it does not close the discharge port side passage 17 and induces surging of the compressor 9. There's nothing to do.

[Effect of idea]

In summary, the present invention provides the following excellent effects.

(1) When the internal combustion engine is in a non-supercharging state during low-load operation, a pressure chamber is formed on the discharge port side of the compressor and pressurized air is accumulated in the pressure chamber to bring the discharge port side of the compressor to a predetermined pressure (positive pressure). Because you can
The bearing part can be isolated from the negative pressure intake system, and leakage of lubricating oil can be prevented.

(2) Even when there is no supercharging, the compressor can perform work based on the pressure difference between the intake port side and the discharge port side, so overrun of the turbine can be prevented.

(3) Since the opening degree of the gate valve is controlled by the gate valve opening degree control means that detects the pressure in the pressure chamber, it is possible to avoid sequentially excessive pressure rise and prevent compressor surging.

[Brief explanation of the drawing]

The figure is a side sectional view showing a preferred embodiment of an internal combustion engine with an exhaust turbo supercharger according to the present invention. In the figure, 1 is an internal combustion engine, 5 is an intake system, 6 is an exhaust system, 8 is a turbine, 8a is an exhaust inlet, 9 is a compressor, 9a is an inlet, 9b is an outlet, 10 is a drive shaft, 12 is an exhaust bypass passage;
13 is an intake bypass passage, 14 is a first bypass on-off valve, 15 is a second bypass on-off valve, 17 is a passage on the discharge port side, 18 is a pressure chamber, 19 is a gate valve, and 20 is a gate valve opening control It is a means.

Claims (1)

[Scope of utility model registration request] An exhaust turbo supercharger that drives a compressor in the intake system by a turbine in the exhaust system via the same drive shaft to supercharge the internal combustion engine, and an exhaust turbo supercharger that is connected to the above-mentioned intake and exhaust systems and supplies intake and exhaust from these compressors and the turbine. an intake/exhaust bypass path to be detoured; a gate valve that closes the discharge port side of the compressor to make the pressure on the discharge port side positive; and an opening degree of the gate valve that is sequentially adjusted as the pressure on the discharge port side increases. An internal combustion engine with an exhaust turbo supercharger, characterized in that it is equipped with means for controlling the opening degree of a gate valve.