JPH0214530B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention relates to a control device for an engine with an exhaust turbo supercharger, and in particular opens and closes a bypass passage of an exhaust turbine in response to boost pressure of a supercharger. A pressure introduction passage for introducing the supercharging pressure into the pressure-responsive valve, and a restriction provided in a part of the pressure introduction passage to reduce the amount of pressure in the pressure introduction passage in the supercharging region to the atmosphere. The present invention relates to a control device for an engine equipped with an exhaust turbo supercharger, which is equipped with a control valve that regulates the exhaust gas in cooperation with the engine.

(Prior art) Conventionally, in engines equipped with an exhaust turbo supercharger in which the supercharger is operated by the exhaust turbine, a bypass passage is provided in the exhaust system to bypass the exhaust turbine, and the supercharging pressure is maintained at a predetermined value. When the supercharging pressure exceeds the supercharging pressure, a pressure-responsive valve is activated to open a bypass passage, thereby bypassing a portion of the exhaust gas and reducing the driving force applied to the supercharger. A wastegate method is used. In this case, a pressure introduction passage for introducing supercharging pressure to the pressure-responsive valve is provided with its upstream end opening into the intake passage between the supercharger and the downstream throttle valve. By the way, boost pressure has been conventionally controlled according to predetermined conditions, and for example, in an engine designed to be able to use both regular gasoline and high-octane gasoline, it is necessary to prevent knocking from occurring. Therefore, the boost pressure is changed depending on the octane number of the fuel gasoline used. As disclosed in Special Publication No. 56-501376,
A relief passage that releases the pressure in the pressure introduction passage in the supercharging region to the atmosphere, and a control valve consisting of an electromagnetic solenoid valve to control the amount of relief through this relief passage are provided. By changing the duty ratio of the electromagnetic control valve, a boost pressure that matches the octane number of the fuel gasoline used is obtained.

By the way, with such electromagnetic control valves, the capacity cannot be changed significantly due to the amount of change in duty ratio, accuracy, and reliability of airtightness.
Therefore, if only this solenoid control valve is used,
It has been difficult to create a supercharging pressure difference that is compatible with both regular gasoline and high octane gasoline. For this reason, at present, the pressure introduction passage is provided with a constriction part whose inner diameter is pre-selected according to the octane number of the gasoline used, and this constriction part cooperates with an electromagnetic control valve to adjust the supercharging pressure suitable for each case. It has gained.

However, the inner diameter of the throttle part is, for example, 0.8 to 1.0 due to the relationship with the capacity (passage system) of the electromagnetic control valve.
mmφ, and as a result, dust contained in the outside air, gasoline from the engine blowback, oil from blow-by, etc. accumulate in the pressure introduction passage, resulting in clogging and reduction of the effective diameter. Since this occurs mainly in the area, there was a risk that the boost pressure could not be controlled or the control accuracy would be insufficient.

(Object of the Invention) Therefore, the present invention provides an engine with an exhaust turbo supercharger that prevents clogging of the pressure introduction passage and reduction of the effective system, and enables precise control of supercharging pressure. The purpose is to provide a control device.

(Structure of the Invention) The present invention opens the upstream end of a pressure introduction passage for introducing supercharging pressure to a pressure-responsive valve constituting a wastegate into an intake passage downstream of a throttle valve located downstream of a supercharger. and a control means for controlling a control valve that controls the amount of relief to the atmosphere in the pressure introduction passage to open when the pressure in the intake passage downstream of the throttle valve is lower than atmospheric pressure. shall be.

(Effects of the Invention) According to the above configuration, the pressure introduction passage is always under negative pressure during normal driving, which occupies most of the entire driving of the automobile, and it is possible to prevent dust, gasoline, oil, etc. from entering this passage. Even if they do get mixed in, the negative pressure causes these foreign substances to be drawn into the engine, so that they can be prevented from staying in the pressure introduction passage for a long period of time, and the supercharging pressure can be precisely controlled.

(Embodiment of the Invention) An embodiment of the present invention will be described in detail below with reference to the drawings.

First, in FIG. 1, an engine 1 has an intake passage 2
The intake passage 2 is provided with a throttle valve 4 and an air flow meter 5 upstream of the throttle valve 4 for measuring the amount of air taken into the engine 1. The output of the air flow meter 5 is given to a control circuit U, which receives the air flow rate signal from the air flow meter 5, as well as a throttle valve opening sensor 6 that generates a signal representing the opening of the throttle valve 4, and the engine rotation. The fuel injection valve 7 generates an output in response to various signals representing the operating state of the engine, and controls the fuel injection valve 7 based on the output.

A supercharger 8 is provided in the intake passage 2 at a position between an air flow meter 5 and a throttle valve 6, and this supercharger 8 is driven by an exhaust turbine 9 provided in the exhaust passage 3. Further, a bypass passage 10 that bypasses the exhaust turbine 9 is formed in the exhaust passage 3, and a pressure-responsive valve 11 is provided in this bypass passage 10. Intake pressure is introduced into this pressure-responsive valve 11 through a pressure introduction passage 12a whose upstream end opens into the intake passage 2 at a position downstream of the throttle valve 4. When the supercharging pressure in the intake passage 2 reaches a predetermined pressure or higher, the pressure-responsive valve 11 is activated to open the bypass passage 10, thereby bypassing a portion of the exhaust gas and providing drive to the supercharger 8. This reduces the force and prevents the supercharging pressure from rising above a predetermined pressure.

The pressure introduction passage 12a communicates with a relief passage 12a that opens into the intake passage 2 on the upstream side of the supercharger 8. A control valve 13 made of an electromagnetic solenoid valve is provided in the relief passage 12b in order to control the amount of pressure relief in the pressure introduction passage 12a through the relief passage 12a. Further, the pressure introduction passage 12a is formed with a constricted portion 14 whose inner diameter is preselected according to the octane number of the gasoline used.

A control device 15 is provided to control the electromagnetic control valve 13, and this control device 15 includes:
a filter circuit 17 that filters the output of the knock sensor 16; a comparison circuit 19 that compares the output of the filter circuit 17 with the output of the comparison level setting circuit 18;
an integrating circuit 20 that integrates the output of the comparison circuit 19;
It consists of a drive circuit 21 that amplifies the output of the integration circuit 20 to form a control valve drive voltage. The electromagnetic control valve 13 is duty-controlled by this drive circuit 21, and cooperates with the throttle section 14 to reduce the pressure in the pressure introduction passage 12a in the supercharging region to the relief passage 12b.
The pressure is relieved to the upstream side of the supercharger 8 through the supercharger 8, and the supercharging pressure is controlled.

On the other hand, the opening degree of the throttle valve 4 is detected by the throttle valve opening degree sensor 6 and inputted to the control circuit U, but the opening degree of the throttle valve 4 is small (e.g.
20 degrees or less), the pressure in the intake passage on the downstream side of the throttle valve 4 is lower than atmospheric pressure, so the opening degree of the throttle valve 4 is, for example,
Throttle valve opening sensor 6 indicates that the angle is 20° or less.
When the output indicates, the control circuit U determines that the pressure in the intake passage on the downstream side of the throttle valve 4 is lower than atmospheric pressure, and controls the drive circuit 21 to fully open the electromagnetic control valve 13. do. As a result, since the upstream end of the pressure introduction passage 12a is open to the intake passage 2 on the downstream side of the throttle valve 4, the inside of the pressure introduction passage 12a is always under negative pressure during normal running. The entry of foreign matter into the intake passage 2 is prevented, and even if it does, during normal driving when the opening degree of the throttle valve 4 is small, the opening of the relief passage 12b in the intake passage 2 (first
Since the pressure at point A in the figure becomes higher than the pressure at the opening of pressure introduction passage 12a (point B in Figure 1), foreign matter mixed into pressure introduction passage 12a is sucked into the engine. For example, when the throttle valve 4 is opened at 20 degrees or less, the operating condition is 80% of the total operating time.
During this period, the solenoid control valve 13
It is clear that by fully opening the pressure introduction passage 12a, foreign matter is prevented from accumulating in the pressure introduction passage 12a.

Next, FIG. 2 shows a flowchart of the control executed by the control circuit U of FIG. 1, and in step 31, the engine speed, throttle valve opening, and engine speed are read. Next, in step 32, throttle valve 4 is
If the judgment result is "NO", the duty of the solenoid control valve 13 is determined as in the conventional method by reading the duty map in step 33. Control is exercised. If the determination result in step 32 is "YES", control moves to step 34 and a command to fully open the control valve is issued. Then, in step 35, the solenoid is energized, and in step 36, the electromagnetic control valve 13 is operated, and the process returns to step 31.

As is clear from the above explanation, in the present invention, the upstream end of the pressure introduction passage 12a, which was conventionally opened between the supercharger 8 and the throttle valve 4 in the intake passage 2, is changed to the downstream side of the throttle valve 4. At the same time, the solenoid control valve 13, which was conventionally fully closed in the non-supercharging region and operated by duty control only in the supercharging region, is opened when the pressure in the intake passage on the downstream side of the throttle valve 4 is lower than atmospheric pressure. By opening when the pressure is low, the constricted portion 14 of the pressure introduction passage 12a is prevented from being clogged.

[Brief explanation of drawings]

FIG. 1 is a schematic diagram showing an embodiment of the control device of the present invention, and FIG. 2 is a flowchart of its control. U... Control circuit, 1... Engine, 2... Intake passage, 3... Exhaust passage, 4... Throttle valve, 6
... Throttle valve opening sensor, 8 ... Supercharger, 9
...Exhaust turbine, 10...Bypass passage, 11
...Pressure responsive valve, 12a...Pressure introduction passage, 12
b... Relief passage, 13... Solenoid control valve, 14
...Aperture section, 15...Control device, 16...Knock sensor.

Claims (1)

[Scope of Claims] 1. A pressure introduction passage for introducing the boost pressure into a pressure-responsive valve that opens and closes the bypass passage of the exhaust turbine in response to the boost pressure of the supercharger, and one end of which is connected to the pressure introduction passage. an exhaust gas comprising: a relief passage connected to the intake passageway and having the other end connected to an intake passageway upstream of the supercharger; a throttle section provided in the pressure introduction passageway; and a control valve provided in the relief passageway. In a turbocharged engine, an upstream end of the pressure introduction passage is opened to an intake passage downstream of a throttle valve located downstream of the supercharger, and a value related to the pressure of the intake passage downstream of the throttle valve is set. and a control means for opening the control valve when it is determined that the pressure in the intake passage on the downstream side of the throttle valve is lower than atmospheric pressure based on the value detected by the detection means. A control device for an engine equipped with an exhaust turbo supercharger.