JPS6238545B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides a method for controlling the boost pressure of an internal combustion engine equipped with a supercharger driven by exhaust gas, that is, an exhaust turbo supercharger, in response to acceleration of the engine. This relates to a device for

In an internal combustion engine equipped with an exhaust turbo supercharger, in order to control the supercharging pressure so that it does not exceed a certain value, an exhaust bypass passage provided for the exhaust turbine in the exhaust turbo supercharger is installed downstream of the blower compressor. A wastegate valve related to the boost pressure is provided, and when the boost pressure reaches the normal setting boost pressure, the wastegate valve is opened and the exhaust gas is bypassed, thereby preventing further increase in the boost pressure. It is well known to prevent this, for example, from Japanese Patent Laid-Open No. 52-59211.

However, when the engine accelerates, the exhaust turbo supercharger suffers from the inertia of the exhaust turbine and blower compressor.
The start of rotation is delayed and the boost pressure rises slowly, and
Since the supercharging pressure is controlled as described above, there is a drawback that sufficient acceleration performance cannot be obtained. Therefore, Japanese Utility Model Application Publication No. 54-37703 as a prior art discloses that when the accelerator pedal is rapidly depressed during acceleration of the engine, the waste gate valve is held in a closed state, so that the supercharging pressure is set to the normal setting of the waste gate valve. It is proposed to improve acceleration performance by increasing the pressure above the boost pressure.

However, in this prior art, as long as the accelerator pedal is depressed rapidly, in other words, unless the sudden depression of the accelerator pedal is stopped, the wastegate valve remains closed and the boost pressure remains at the normal level of the wastegate valve. The boost pressure will suddenly rise significantly above the set boost pressure, and the value of this sudden increase in boost pressure is completely unpredictable and may lead to extreme supercharging.
There is a high risk of damaging the exhaust turbo supercharger.
Furthermore, if you fear this and stop pressing the access pedal too early, the boost pressure will drop rapidly to the normally set boost pressure of the wastegate valve, making it impossible to obtain sufficient acceleration performance.

The present invention improves acceleration performance by keeping the wastegate valve closed during engine acceleration, by delaying the increase in boost pressure by an appropriate amount of time during the first pressure transmission path to the wastegate valve. providing a delay means adapted to communicate to the wastegate valve;
When the engine accelerates, the wastegate valve is kept closed for the appropriate period of time so that the boost pressure rises above the normally set boost pressure, while the delay means in the first pressure transmission passage A pressure opening/closing valve is provided in a second pressure transmission passage forming a bypass, which releases the delay of the delay means when the boost pressure reaches an acceleration setting boost pressure that is appropriately higher than the normal setting boost pressure. By configuring the upper limit of the boost pressure within the delay period of the delay means to improve acceleration performance without causing extreme supercharging, and in addition to this, the pressure on/off valve This prevents sudden changes and fluctuations in the boost pressure due to opening/closing operations, and controls the boost pressure smoothly and stably.

The present invention will be explained below with reference to drawings of embodiments. In the drawings, 1 is a three-cylinder internal combustion engine having an intake manifold 2 and an exhaust manifold 3, and 4 is an exhaust turbo supercharger in which an exhaust turbine 5 and a blower compressor 6 are directly connected. In the supercharging passage 7 connecting the discharge side of the blower compressor 6 and the intake manifold 2 in the exhaust turbo supercharger 4, a surge tank 8 for eliminating pulsation and a carburetor 10 with a throttle valve 9 are installed. The tank 8 is provided on the upstream side, an air cleaner 11 is connected to the suction side of the blower compressor 6, and the exhaust gas is connected to the inlet side of the exhaust turbine 5 in the exhaust turbo supercharger 4 via an exhaust passage 12. Manifold 3 is exhaust turbine 5
An exhaust pipe 13 to the atmosphere is connected to each outlet side.

Reference numeral 14 indicates an exhaust bypass passage provided for the exhaust turbine 5 between the exhaust passage 12 and the exhaust pipe 13, and 15 indicates a pressure-operated wastegate valve provided in the bypass passage 14. The valve 14 includes a spring 17 that normally biases the valve body 16 in the closing direction, and a supercharging passage 7 or a surge tank 8 between the blower compressor 6 and the carburetor 10 is provided in the pressure chamber 18. By introducing the supercharging pressure of
350 mmHg), the valve body 16 opens against the force of the spring 17.

And the pressure chamber 1 of the waste gate valve 15
A delay means 22 is provided in the first pressure transmission passage 19 to the waste gate 8, and a delay means 22 is provided in which a throttle orifice 20 and a check valve 21 which opens only in the direction toward the supercharging passage 7 are arranged in parallel. Pressure chamber 18 of valve 15
A second pressure transmission passage 23 is provided between the supercharging passage 7 or the surge tank 8 and constitutes a parallel bypass to the delay means 22 in the first pressure transmission passage 19. In the pressure transmission passage 23,
A pressure on/off valve 24 is provided.

This pressure opening/closing valve 24 has a diaphragm 28 that closes the port 25 with a spring 27 in an atmosphere communication chamber 26.
and the acceleration setting boost pressure P ₁ (for example, about 420 mmHg) whose boost pressure is appropriately higher than the normal setting boost pressure Po.
level), the port 25 is opened, and the atmospheric communication chamber 26 in the pressure opening/closing valve 24 is opened.
The communication path 29 to the atmosphere includes a throttle orifice 30.
and a check valve 31 which opens only in the direction toward the atmosphere communication chamber 26 are provided in parallel.

Note that the auxiliary delay means 32 is a throttle orifice 30.
You can also just eat it alone.

In this configuration, when the supercharging pressure in the supercharging passage 7 or the surge tank 8 drops below the normal setting supercharging pressure Po, the check valve 21 in the delay means 22 of the first pressure transmission passage 19 is opened. Then,
Since the drop in supercharging pressure is transmitted to the pressure chamber 18 of the wastegate valve 15 without any time delay, the valve element 16 of the wastegate valve 15 immediately closes.

On the other hand, the increase in the supercharging pressure in the supercharging passage 7 or the surge tank 8 is caused by the closing of the check valve 21 in the delay means 22 in the first pressure transmission passage 19, so that the pressure increases only through the throttle orifice 20. The signal is delayed and transmitted to the chamber 18. In this case, during normal acceleration in which the throttle valve 9 is opened slowly, the engine speed increases slowly, and the exhaust turbocharger 4 speed increases slowly, so the boost pressure also increases slowly. Since it is not subject to the delay restriction of the throttle orifice 20, the increase in supercharging pressure is directly transmitted to the pressure chamber 18, and the supercharging pressure becomes the normally set supercharging pressure at the wastegate valve 15.
When it becomes Po, the waste gate valve 15
Since the valve body 16 opens to bypass the exhaust gas to the exhaust turbine 5, the boost pressure is controlled so as not to exceed the normally set boost pressure Po, and the boost pressure characteristics with respect to the rotation speed at this time are becomes a curve A shown as a solid line in FIG.

However, when the throttle valve 9 is suddenly opened and the throttle valve 9 is suddenly opened for sudden acceleration, the engine speed rises quickly, and the exhaust turbocharger 4 speed rises quickly, and therefore the supercharging pressure rises rapidly. The transmission of the sudden increase in pressure to the pressure chamber 18 is delayed appropriately due to the regulation at the orifice 20, and during this time the valve body 16 of the waste gate valve 15 is held in the closed state, so that the boost pressure to the engine is maintained at the normal level. When the set supercharging pressure Po is exceeded and supercharging eventually reaches the acceleration setting supercharging pressure _P1 of the pressure on-off valve 24 in the second pressure transmission passage 23, the pressure on-off valve 24 opens and the supercharging pressure is second
By transmitting the pressure to the pressure chamber 18 via the pressure transmission passage 23, the delay action by the delay means 22 is canceled and the wastegate valve 15 is opened, bypassing the exhaust gas to the exhaust turbine 5. is controlled to return to the normal set boost pressure Po.

In other words, when the engine is rapidly accelerating, the boost pressure once increases beyond the normal set boost pressure Po, as shown by the characteristic curve B shown by the dashed line in Figure 2, and then reaches the normal set boost pressure Po. During this period, the engine's output increases and acceleration performance improves.However, at this time, the maximum boost pressure is regulated so that it does not exceed the acceleration setting boost pressure P ₁ , so extreme supercharging is prevented. can be prevented.

By providing the auxiliary delay means 32 in the communication path 29 of the atmosphere communication chamber 26 to the atmosphere in the pressure on-off valve 24, the boost pressure rises to the acceleration setting supercharging pressure _P1 , and the pressure on-off valve 24 opens, the pressure opening/closing valve 24 gradually opens in response to the air in the atmosphere communication chamber 26 leaking from the throttle orifice 30 in the auxiliary delay means 32, so the pressure opening/closing valve 24 opens suddenly. As a result, the wastegate valve opens suddenly and the boost pressure suddenly drops from the acceleration setting boost pressure P ₁ to the normal setting boost pressure Po, and the pressure on/off valve 24 repeats opening and closing, causing the boost pressure to fluctuate. This can be prevented. Therefore, the supercharging pressure characteristic line B has a smooth and stable shape without waves.

In addition, FIG. 3 shows a restrictor orifice 33 located downstream of the pressure on-off valve 25 in the second pressure transmission passage 23.
and a check valve 34 arranged in parallel.
5 is provided (however, the second delay means 25 may be only the throttle orifice 33).
When the delay means 35 is provided, the pressure transmission to the pressure chamber 18 due to the opening of the pressure on-off valve 24 is delayed by the second delay means 35, so that the boost pressure is increased slightly after the acceleration setting boost pressure P ₁ is exceeded. Gently set normal boost pressure
Po, and the boost pressure characteristics at that time will be like the curve C shown by the two-dot chain line in Figure 2, and the period in which the boost pressure exceeds the normal setting Po will be longer, so acceleration performance will further improve. In this case as well, by providing the auxiliary delay means 32 in the communication path 29 of the atmosphere communication chamber 26 to the atmosphere in the pressure on-off valve 24, the boost pressure characteristic curve C can be made smooth and stable. It can be made into something.

Furthermore, FIG. 4 shows the first pressure transmission passage 19.
An embodiment in which an atmosphere communication passage 36 is connected to the downstream side of the delay means 22 in the passage 19, and a throttle orifice 37 is provided in the atmosphere communication passage 36 to restrict leakage of supercharging pressure to the atmosphere. show. The supercharging characteristic line in this embodiment is approximately the same as that in the second embodiment shown in FIG.
Similar functions and effects can be obtained by providing the auxiliary delay means 32 in the communication path 29 of the atmosphere communication chamber 26 to the atmosphere.

In summary, the present invention provides an engine with an exhaust turbo supercharger, which is provided with an exhaust bypass passage that communicates the upstream side and the downstream side of the exhaust turbine, and is equipped with a pressure-operated wastegate valve in the bypass passage. The supercharging passage downstream of the blower compressor in the exhaust turbo supercharger and the pressure chamber of the wastegate valve are connected through a first pressure transmission passage having a delay means for delaying and transmitting pressure only in the direction of the wastegate valve. While communicating, the first
In parallel with the delay means in the pressure transmission passage, the pressure chamber of the supercharging passage downstream of the blower compressor and the waste gate valve is connected via a pressure opening/closing valve with an atmospheric communication chamber that opens when the supercharging pressure exceeds a predetermined level. A second pressure transmission passage for communication is provided, and an auxiliary delay means for delaying leakage to the atmosphere is provided in the communication passage from the atmosphere communication chamber to the atmosphere in the pressure opening/closing valve, so that the boost pressure is not transferred to the engine. During acceleration, the boost pressure can be raised within a range that does not exceed the set boost pressure in the pressure on/off valve, so the acceleration performance of the engine can be safely improved without unnecessary supercharging, while the pressure on/off valve By means of the auxiliary delay means installed in the atmosphere communication chamber, the boost pressure during acceleration can be controlled to a smooth and stable characteristic curve, and therefore the engine output can be controlled due to sudden changes and fluctuations in the boost pressure. It has the effect of improving acceleration feeling with less sudden changes and fluctuations.

[Brief explanation of the drawing]

The drawings show embodiments of the present invention; FIG. 1 is a diagram of the first embodiment, FIG. 2 is a diagram showing boost pressure characteristics with respect to rotational speed, FIG. 3 is a diagram of the second embodiment, and FIG. FIG. 4 is a diagram of the third embodiment. 1...engine, 4...exhaust turbo supercharger, 5...
Exhaust turbine, 6... Blower compressor, 14...
Exhaust bypass passage, 15... waste gate valve,
18...pressure chamber, 19...first pressure transmission passage,
22...First delay means, 23...Second pressure transmission passage, 24...Pressure opening/closing valve, 26...Atmospheric communication chamber, 29...Communication passage, 32...Auxiliary delay means.

Claims (1)

[Claims] 1. In an engine equipped with an exhaust turbo supercharger, which is provided with an exhaust bypass passage that communicates the upstream side and the downstream side of the exhaust turbine, and is equipped with a pressure-operated wastegate valve in the bypass passage, the exhaust turbo supercharger The supercharging passage downstream of the blower compressor and the pressure chamber of the wastegate valve are communicated via a first pressure transmission passage having a delay means for delaying and transmitting pressure only in the direction of the wastegate valve; In parallel with the delay means in the first pressure transmission passage, there is provided a pressure on/off valve with an atmosphere communication chamber that opens the pressure chamber of the waste gate valve and the supercharging passage downstream of the blower compressor when the supercharging pressure exceeds a predetermined level. A second pressure transmission passage communicating through the pressure on/off valve is provided, and an auxiliary delay means for delaying leakage to the atmosphere is provided in the communication passage between the atmosphere communication chamber and the atmosphere in the pressure opening/closing valve. A boost pressure control device for an exhaust turbocharged internal combustion engine.