JPS61101626A - Supercharge pressure control unit - Google Patents

Abstract

PURPOSE:To prevent the engine output from lowering and the air-fuel ratio from changing by controlling to open or close a waste gate valve based on the detected value of the atmospheric pressure and/or the atmospheric temperature so that knocking or the cylinder inside pressure assumes a predetermined allowable value. CONSTITUTION:In the control unit in which a bypass 7 is connected to an exhaust passage 6 so that the bypass 7 makes detour of a turbine 3 of a supercharger 1, and a waste gate valve 8 is provided swingably around a pin 9 at the joint portion on the upstream side, said valve 8 is opened by the output of a step motor 18 controlled by an electronic control unit (ECU)20 through a connecting rod 19 against a force exerted by a tension coil spring 17. The ECU is designed to control the opening degree of the valve 8 so that the cylinder inside pressure detected by a cylinder inside pressure sensor 21 provided by being exposed within a combustion chamber 4 assumes a set maximum value, in a case where the atmospheric pressure detected by an atmospheric pressure sensor is lower than a reference atmospheric pressure and/or the atmospheric temperature detected by an atmospheric temperature sensor is higher than a reference atmospheric temperature.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a boost pressure control device for a turbocharger installed in an internal combustion engine.

Conventional boost pressure control is performed by controlling the opening and closing of a bypass that bypasses the turbine of a turbocharger using a wastegate valve. To explain this with reference to FIG. 5, the turbocharger I has a compressor 2 and a turbine 3 that are coaxially connected and rotate integrally,
The compressor 2 is disposed midway through an intake passage 5 leading from an air cleaner to a combustion chamber 4 of the engine, and the turbine 3 is disposed midway through an exhaust passage 6 leading from the combustion chamber 4 of the engine to a muffler. In the exhaust passage 6, a turbine 3
A bypass 7 is connected to communicate the second flow with the downstream, and a wastegate valve 8 is provided on the upstream side of the connection so as to be able to swing around a pin 9. It is designed to open and close. The wastegate valve 8 is opened and closed by an actuator 10.

The actuator 10 includes a first pressure chamber 12 which is communicated with the intake passage 5 downstream of the compressor 2 through a conduit 11, and a second pressure chamber 12 which is separated by a diaphragm 13 and is open to the atmosphere.
The pressure chamber 14 and the diaphragm 13 are always connected to the first pressure chamber 12.
A compression coil spring 15 is connected to the diaphragm 13 at one end and a wastegate valve 8 at the other end.
and an actuating rod 16 pivotally connected to the actuating rod 16.

The turbine 3 is rotated by exhaust gas flowing from the combustion chamber 4 through the exhaust passage 6, and this rotation causes the compressor 2 to rotate, supercharging the air taken in from the air cleaner, and expelling the air from the intake passage 5 into the combustion chamber 4. Send it in. When the engine speed increases and the turbine 3 and compressor 2 rotate at high speed, the pressure of the supercharging air sent into the combustion chamber 4 also increases. When this supercharging pressure becomes larger than the set pressure of the spring 15 of the actuator IO, the diaphragm 13 is pushed down, and the wastegate valve 8 swings around the pin 9 via the rod 16 to open the bypass inlet lower a. As a result, part of the exhaust gas from the combustion chamber 4 flows downstream of the turbine 3 through the bypass 7, suppressing an increase in rotation of the turbine 3, and maintaining the supercharging pressure by the compressor 2 at the set pressure.

Such control of boost pressure not only prevents the turbine 3 and compressor 2 from seizing due to overspeed.

In the case of a gasoline engine, this is absolutely necessary to prevent knocking. However, in the wastegate valve actuator 10 in the conventional device as shown in FIG. Even if the boost pressure is introduced, the waste gate valve 8 will open, and the boost pressure will be controlled to a low level that does not reach the maximum boost pressure set at low altitudes. As a result, the engine output decreases, and the amount of air entering the combustion chamber 4 decreases, causing a change in the air-fuel ratio.If this is not corrected, diesel engines will contain a large amount of black smoke in their exhaust gas. .

By the way, in the case of a gasoline engine, the maximum boost pressure is set high in the engine's low-speed rotation range to increase engine output, and the maximum boost pressure is set low in the high-speed rotation range to prevent knocking. It is desirable to suppress this. In the case of a diesel engine, similarly, in the low speed range of the engine, supercharging is increased to increase engine output, and in the high speed range, supercharging can be suppressed so as not to exceed the maximum allowable cylinder pressure (Pmax). is desired. In this way, the permissible knocking limit in the case of a gasoline engine and the maximum permissible in-cylinder pressure in the case of a diesel engine serve as a guideline for how much supercharging is allowed.

Therefore, an object of the present invention is to provide a boost pressure control device that corrects boost pressure according to fluctuations in environmental conditions such as atmospheric pressure using the knocking allowable limit or maximum allowable cylinder pressure as a guide. There is a particular thing.

The boost pressure control device according to the present invention includes a sensor for detecting atmospheric pressure and/or atmospheric temperature, a sensor for detecting engine knocking or cylinder pressure, and a sensor for detecting engine knocking or cylinder pressure to a predetermined tolerance value. and means for controlling the opening and closing of the wastegate valve based on signals from a sensor that detects atmospheric pressure and/or atmospheric temperature.

When the atmospheric pressure decreases, the supercharging pressure also decreases, so if you do not supercharge the engine even more than when driving on a single losing ground, the engine output will decrease. Therefore, boost pressure is increased until the knocking permissible limit or maximum permissible cylinder pressure is reached to increase engine output.

When the atmospheric temperature rises, the supercharging pressure decreases compared to when the temperature is low, so even in such a case, extra supercharging is performed to increase engine output. It is desirable to precisely control boost pressure by taking into account both atmospheric pressure and atmospheric temperature conditions.

An embodiment of the present invention will be described below with reference to FIG. Note that the reference numerals used in the description of the conventional example in FIG. 5 are used for similar members. In this invention, the structure of the device itself is almost the same as that of the conventional example, but the structure for controlling the opening and closing of the waste gate valve 8 is different from the conventional example. The wastegate valve 8 is provided with a tension coil spring 17 at its rear end, and is given a counterclockwise rotational habit around the pin 9 so that its tip closes the bypass man lower a in a normal state. It is being Also at the rear end of wastegate valve 8.

One end of a connecting rod 19 is connected to the step motor 18, and the other end of the connecting rod 19 is pivotally connected. The step motor 18 is driven by a signal from an electronic control unit (ECU) 20.

In addition to signals from an in-cylinder pressure sensor 21 provided exposed in the combustion chamber 4, the ECU 20 also includes an engine rotation speed sensor,
Signals from a load sensor, atmospheric pressure sensor, atmospheric temperature sensor, etc. are input.

FIG. 2 shows an example of how this device is controlled. First, a predetermined maximum allowable cylinder pressure (Pmax) is set by matching the engine.

Next, based on the signals from the engine speed sensor and load sensor, it is determined whether the operating conditions at that time are within the waste gate valve (WGV) control range as shown in Figure 2a. Since there is no need for control, control ends immediately. If it is within the control range, it is determined whether the cylinder pressure has reached the set Pmax based on the signal from the cylinder pressure sensor 21, and if it has, no further control is necessary, so control is performed. will end just like that. If the predetermined Pmax has not been reached, the signals from the atmospheric pressure sensor and/or atmospheric temperature sensor indicate that the cylinder pressure is lower than the standard atmospheric pressure and/or the atmospheric temperature is higher than the standard atmospheric pressure. The opening degree of the waste gate valve 8 is set so that Pmax becomes Pmax, and the step motor 18 is driven so that the opening degree is reached.

In another embodiment of the invention shown in FIG.

Wastegate valve actuator I similar to the conventional example
An atmosphere release pipe 22 is connected to the first pressure chamber 12, and a pressure control solenoid valve 23 is provided on the atmosphere release pipe 22. This electromagnetic valve 23 is driven and controlled by the ECU 20, which receives signals representing operating conditions and environmental conditions similar to those in the above embodiment. Namely.

When the atmospheric pressure sensor detects a decrease in atmospheric pressure and/or the atmospheric temperature sensor detects an increase in temperature, a map representing the amount of boost pressure relief by the solenoid valve 23 in response to a predetermined decrease in atmospheric pressure and/or increase in atmospheric temperature is displayed. Therefore, the solenoid valve 23 is controlled. For example, when the atmospheric pressure is lower than the standard atmospheric pressure state by ΔP, the solenoid valve 23 is controlled so that the pressure in the first pressure chamber 12 is also lower than the boost pressure at that time by ΔP. By doing this, the maximum boost pressure set by the spring 15 is maintained in the standard atmospheric pressure state, and even when traveling at high altitudes and/or high temperatures, the waste gate valve 8 is activated in the same manner as when traveling at low altitudes and/or low temperatures. The opening/closing control is performed and Pma
x is kept constant.

In yet another embodiment of the invention shown in FIG.
The second pressure chamber 14 of the wastegate valve actuator 10 is sealed by a sealing bellows 24, and a second conduction pipe 26 is provided with a pressure control solenoid valve 25 in the middle thereof.
one end is connected. The other end of the second conduit pipe 26 connects the boost pressure downstream of the compressor 2 to the first
It is connected in the middle of the first conduction pipe 11 for introducing into the pressure chamber 12 .

Under normal conditions, the solenoid valve 2 is activated by a signal from the ECU 20.
5 operates to open the second pressure chamber 14 of the actuator 10 to the atmosphere, and the actuator 10 operates in the same manner as the normal actuator 10. When the atmospheric pressure sensor detects a decrease in atmospheric pressure and/or when the atmospheric temperature sensor detects an increase in temperature, the ECU2
0 actuates the solenoid valve 25 to introduce a portion of the supercharging pressure into the second pressure chamber 14 of the actuator IO to increase back pressure. In this way, the wastegate valve 8 must be supercharged more than in the case of standard atmospheric pressure and/or standard atmospheric temperature.
does not open, thus correcting the lack of supercharging due to a drop in atmospheric pressure and/or a rise in atmospheric temperature.

Instead of introducing a part of the supercharging pressure into the second pressure chamber 14 of the actuator 10, negative pressure generated downstream of the vacuum pump or throttle valve of the engine is also introduced via the pressure control solenoid valve 25 to reduce the pressure of the spring 15. The back pressure within the second pressure chamber 14 may be controlled in combination with the restoring force.

That is, under normal conditions, a certain value of negative pressure is introduced into the second pressure chamber 14 to keep the back pressure in the second pressure chamber 14 constant, and when driving at high altitudes, part of the negative pressure is removed by the solenoid valve 25. is released to increase the back pressure in the second pressure chamber 14, and the waste gate (waste gate) is prevented from opening unless the back pressure in the second pressure chamber 14 is increased.

In each of the embodiments described above, supercharging is controlled so that the cylinder pressure reaches Pmax, but supercharging may be controlled using a knock sensor so that the knocking tolerance limit is reached. Also,
If a suitable engine torque sensor is available, it may be used to control the engine output to be constant.

As described above, the boost pressure control device according to the present invention includes a sensor for detecting atmospheric pressure and/or atmospheric temperature, a sensor for detecting engine knocking or cylinder pressure, and a sensor for detecting engine knocking or cylinder pressure. The system is equipped with a means for controlling the opening and closing of the wastegate valve based on signals from atmospheric pressure and/or atmospheric temperature sensors to maintain a predetermined tolerance value, so boost pressure can be appropriately corrected in response to changes in environmental conditions. This makes it possible to prevent a decrease in engine output and changes in the air-fuel ratio, etc.

[Brief explanation of the drawing]

FIG. 1 is a schematic configuration diagram showing one embodiment of the present invention, and FIG.
The figure shows the control flowchart of the embodiment shown in FIG.
Figure a is a graph showing the waste gate valve control area, Figure 3 is a schematic configuration diagram showing the main part of another embodiment of the invention, and Figure 4 is a graph showing the waste gate valve control area. FIG. 5 is a schematic configuration diagram showing yet another embodiment of the present invention, and FIG. 5 is a schematic configuration diagram showing an example of a conventional boost pressure control device. 1...Turbocharger, 2...Compressor, 3...Turbine, 4...Combustion chamber, 5...
Intake passage, 6...exhaust passage, 7...bypass,
8... Waste gate valve, 10... Waste gate valve actuator, 11... Conduit pipe, 12... First pressure chamber, 13... Diaphragm, 14... First 2 pressure chamber, 15... compression coil, r spring, 16... actuating rod, 18
...Step motor, 21...Cylinder pressure sensor,
23.25...Pressure control solenoid valve, 24...Sealing bellows. IP) δ KufP) D Warm--ISl12Q-

Claims (1)

[Claims] The boost pressure of the compressor of the turbocharger is controlled by a wastegate valve to open and close a bypass that leads from an exhaust passage for supplying exhaust gas from the combustion chamber of the engine to the turbine of the turbocharger to an exhaust passage downstream of the turbine. A device for controlling a system, comprising: a sensor for detecting atmospheric pressure and/or atmospheric temperature; a sensor for detecting engine knocking or cylinder pressure; A supercharging pressure control device comprising means for controlling opening and closing of the waste gate valve based on a signal from a sensor that detects the atmospheric pressure and/or the atmospheric temperature.