JPH0415950Y2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a device for controlling boost pressure when a detector that obtains data for determining boost pressure fails.

[Conventional technology]

It is already known to provide a supercharger such as a turbocharger to improve the output of an internal combustion engine. Normally, boost pressure is determined based on data such as water temperature and intake pipe pressure, and Japanese Utility Model Application Publication No. 58-152520 states that the set value of maximum boost pressure is calculated according to engine speed and cooling water temperature. Japanese Patent Publication No. 58-55330 discloses a configuration in which the set value of the maximum boost pressure is determined according to the temperature of the engine body. Further, Japanese Patent Application Laid-open No. 57-56626 discloses a configuration in which the boost pressure is reduced when a knock sensor detects the occurrence of knocking.

In addition, the applicant's earlier application, JP-A-59-
Publication No. 165841 states that when a disconnection of the signal line from the vehicle speed sensor is detected, the exhaust relief valve is fully opened in order to lower the engine's output at high loads by lowering the boost pressure. A vehicle speed limiter is listed.

[The problem that the idea aims to solve]

In these conventional techniques, no special consideration is given to the case where the rotation speed sensor, temperature sensor, or the like outputs an abnormal signal due to a failure. In the conventional technology disclosed in Japanese Patent Application Laid-Open No. 59-165841, when the signal line from the vehicle speed sensor is disconnected, the exhaust relief valve is fully opened to reduce the boost pressure. The safety of not only vehicles but also internal combustion engines and superchargers is ensured, but if we were to follow this example and take similar measures for the failure of many sensors other than the vehicle speed sensor, which sensor would fail? Even if there is a failure of the sensor, which may not have a significant effect on the supercharging pressure, the supercharging effect will not be obtained.

The present invention focuses on this problem of the conventional technology, and protects the internal combustion engine and the supercharger body by reducing the boost pressure when the knock control sensor, pressure sensor, water temperature sensor, etc. fail. However, the problem that the invention aims to solve is to maintain the boost pressure as high as possible within a safe range and maintain high engine efficiency.

[Means to solve the problem]

A supercharging pressure control device for an internal combustion engine according to the present invention includes a waste gate valve provided in a bypass passage that bypasses a turbine wheel of a turbocharger, a diaphragm type actuator that opens and closes the waste gate valve, and a diaphragm type actuator of the actuator. A variable pressure chamber is formed on the side to accept the boost pressure of the intake passage and bias the diaphragm in a direction that increases the opening degree of the waste gate valve according to the magnitude of the boost pressure, and the variable pressure chamber is connected to the atmosphere. a switching valve provided in a passage that opens to the air, a knock control sensor that detects occurrence of knocking, a pressure sensor that detects supercharging pressure in the intake passage, a water temperature sensor that detects cooling water temperature, and the knock control sensor, By receiving the signals outputted by the pressure sensor and the water temperature sensor and controlling the duty ratio of the switching valve, the pressure in the variable pressure chamber can be changed in multiple stages, and the occurrence of an abnormality in each of the sensors can be detected. It is equipped with an electronic control unit that can detect
The electronic control unit is configured to include the knock control sensor or a plurality of the sensors, the pressure sensor,
Alternatively, when it is detected that there is an abnormality in any of the water temperature sensors, the opening degree of the switching valve is set to be increased in accordance with the order of description.

[Effect]

Normally, when the pressure in the intake passage, that is, the boost pressure, increases, the pressure in the variable pressure chamber that receives it increases, and this pressure pushes the diaphragm and increases the opening of the waste gate valve. While boost pressure is kept approximately constant, the electronic control unit accepts signals from various sensors and performs calculations, allowing the engine to achieve maximum efficiency within a safe range depending on the operating conditions at the time. In this way, the duty ratio of the switching valve is controlled to release a portion of the pressure in the variable pressure chamber to the atmosphere, and the opening characteristics of the waste gate valve are changed to increase the supercharging pressure as much as possible.

When the electronic control unit detects that a specific sensor is emitting an abnormal signal, the electronic control unit reduces the duty output to be sent to the switching valve at a predetermined rate depending on the type of abnormal sensor. , the valve opening time ratio (duty ratio) of the switching valve is decreased from the calculated value, and the pressure in the variable pressure chamber is relatively increased. As a result, the opening degree of the waste gate valve becomes relatively large, preventing an increase in supercharging pressure and protecting the engine body and the supercharger body.

In this case, the feature of the present invention is that the degree of reduction in the valve opening time ratio of the switching valve is changed depending on the type of sensor that has become abnormal, so that excessive boost pressure is applied to the engine. The electronic control unit is set so that the sensor that detects a more serious factor in the situation will cause the opening degree of the switching valve to be smaller when the sensor becomes abnormal.

In other words, when the knock control sensor or multiple sensors that detect important knocking are abnormal, the opening of the switching valve is set to the minimum, and then the opening of the pressure sensor and water temperature sensor is increased in that order. , as in the prior art,
Regardless of which sensor becomes abnormal, the system does not uniformly lower the boost pressure, but operates to maintain the boost pressure as high as possible and increase engine efficiency within a safe range.

〔Example〕

FIG. 1 shows an internal combustion engine to which a boost pressure control device according to an embodiment of the present invention is applied. In this diagram,
A turbocharger 3 for supercharging high pressure air into a combustion chamber 2 formed in a cylinder 1 has a turbine wheel 4, a compressor wheel 5, and a shaft 6 connecting the centers of these wheels 4 and 5. The turbine wheel 4 and the compressor wheel 5 are provided in an exhaust passage 7 and an intake passage 8, respectively, which communicate with the combustion chamber 2, and rotate around the axis of the shaft 6. That is, the compressor wheel 5 rotates as the turbine wheel 4 is rotationally driven by the exhaust gas passing through the exhaust passage 7, and as a result, the air taken into the intake passage 8 from the atmosphere port 9 is brought into high pressure and combusted. It is fed to the chamber 2 side.

A throttle valve 10 is provided in the middle of the intake passage 8. A fuel injection valve 11 is provided downstream of the throttle valve 10 and near the combustion chamber 2, and a pressure sensor 51 is provided immediately downstream of the throttle valve 10 to detect intake pipe pressure.

The waste gate valve 20 limits the rotational speed of the turbocharger 3 to keep the supercharging pressure to a constant value, and opens and closes a bypass passage 21 that connects the upstream and downstream sides of the turbine wheel 4 in the exhaust passage 7. The diaphragm device 22, which is an actuator that opens and closes the wastegate valve 20, includes a shell 23, a diaphragm 26 that partitions the shell into a variable pressure chamber 24 and a spring chamber 25, and a spring 27 provided in the spring chamber 25. The variable pressure chamber 24 is constantly communicated with the intake passage 8 via a passage 28, and is also able to communicate with the atmosphere via a switching valve 29 whose duty ratio is controlled by an electronic control unit, which will be described later. A rod 31 fixed to the diaphragm 26 projects from the spring chamber 25 to the outside of the shell 23 and is connected to a link 32 provided in the tube wall forming the bypass passage 21. This link 32 is coupled to the wastegate valve 20. When the pressure in the variable pressure chamber 24 overcomes the elastic force of the spring 27, the wastegate valve 20 opens the bypass passage 21, thereby reducing the amount of exhaust gas supplied to the turbine wheel 4, and reducing the amount of exhaust gas supplied to the turbine wheel 4. 4 is suppressed, and the supercharging pressure of the turbocharger is limited.

The switching valve 29 is controlled by an electronic control section 40 consisting of a microcomputer. Electronic control section 4
0 includes a central processing unit (CPU) 41, a random access memory (RAM) 42, a read only memory (ROM) 43, an input/output port (I/O port) 44, and a bus line 45 interconnecting these. The I/O port 44 has a switching valve 2.
In addition to the solenoid 30 for driving the valve body 9,
A pressure sensor 51, a knock control sensor 52 for detecting occurrence of knocking, and a water temperature sensor 53 for detecting cooling water temperature are connected.

The electronic control unit 40 periodically repeats energization and demagnetization of the solenoid 30, that is, the high pressure air in the intake passage 8 supplied to the pressure transformation chamber 24 of the diaphragm device 22 via the passage 28 is transferred to the switching valve 29.
Partially released into the atmosphere by intermittent valve opening operations. As a result, waste gate valve 20
The bypass passage 21 is opened in accordance with the ratio of opening/closing time of the switching valve 29 that causes a change in the pressure acting on the variable pressure chamber, that is, the duty ratio, and thereby the supercharging pressure can be controlled. For example, when the duty output is 100%, the switching valve 29 is always open to the atmosphere, the pressure in the variable pressure chamber 24 is close to atmospheric pressure, and the waste gate valve 20 tends to close the bypass passage 21 due to the elastic force of the spring 27. Therefore, the boost pressure becomes relatively high (see Figure 2). on the other hand,
When the duty output is 0%, the switching valve 29 always communicates with the intake passage 8, the pressure in the variable pressure chamber 24 becomes high, and the waste gate valve 20 resists the spring 27 and easily opens the bypass passage 21. The electronic control unit 40 controls the switching valve in order to determine the boost pressure based on the map in the ROM 43 according to the output signals of the pressure sensor 51, knock control sensor 52, and water temperature sensor 53, the load at that time, and the engine rotation speed. 29 to control the duty ratio.
In this embodiment, when any one of the sensors 51, 52, 53 becomes abnormal, the electronic control unit 40 controls the duty output according to the sensor in which the abnormality is detected. That is, when an abnormality in the knock control sensor 52 is detected, the duty output is set to 0%, when an abnormality in the pressure sensor 51 is detected, the duty output is set to 50%, and when an abnormality in the water temperature sensor 53 is detected. When this happens, the duty output is set to 70%. However, when a plurality of sensors detect an abnormality, the duty output is set to 0%. Note that an abnormality in each sensor is detected when the output signal from each sensor deviates from a predetermined range or when the content of the output signal does not change even after a predetermined period of time has elapsed.

[Effect of idea]

As described above, according to the present invention, even if each sensor is in an abnormal state, the boost pressure is not reduced uniformly, but the boost pressure is increased to the extent that safety can be ensured depending on the type of abnormal sensor. Therefore, while protecting the internal combustion engine main body or the supercharger main body, it is possible to prevent unnecessary reduction in supercharging pressure as much as possible, and to operate the internal combustion engine efficiently.

[Brief explanation of the drawing]

FIG. 1 is a sectional view showing an internal combustion engine to which an embodiment of the present invention is applied, and FIG. 2 is a graph showing the relationship between engine speed and boost pressure using duty ratio as a parameter. 3...Supercharger, 20...Wastegate valve (control means), 21...Bypass passage (control means), 40...Electronic control section (failure detection means).

Claims (1)

[Scope of utility model registration request] a wastegate valve provided in a bypass passage that bypasses a turbine wheel of a turbocharger; a diaphragm-type actuator that opens and closes the wastegate valve; and a diaphragm-type actuator formed on one side of a diaphragm of the actuator to receive supercharging pressure in an intake passage. , a variable pressure chamber that biases the diaphragm in a direction in which the opening degree of the waste gate valve increases in accordance with the magnitude of boost pressure; a switching valve provided in a passage that opens the variable pressure chamber to the atmosphere; a knock control sensor that detects the occurrence of a knock, a pressure sensor that detects the supercharging pressure in the intake passage, a water temperature sensor that detects the cooling water temperature, and signals output by the knock control sensor, the pressure sensor, and the water temperature sensor, respectively. and an electronic control unit capable of changing the pressure in the variable pressure chamber in multiple stages by accepting the changeover valve and controlling the duty ratio of the switching valve, and also capable of detecting the occurrence of an abnormality in each of the sensors. When the electronic control unit detects that there is an abnormality in the knock control sensor or the plurality of sensors, the pressure sensor, or the water temperature sensor, the electronic control unit opens the switching valve according to the stated order. A supercharging pressure control device for an internal combustion engine, characterized in that the boost pressure control device is set to increase the boost pressure.