JPS6040729A - Suction air pressure controller for supercharged internal-combustion engine - Google Patents

Abstract

PURPOSE:To boost supercharging pressure at highland, by controlling a waste gate valve, which is installed alongside in a bypass passage bypassing a turbine of a supercharger, with absolute pressure in a suction pipe, while keeping the waste gate valve closed till the absolute pressure goes up beyond the specified value. CONSTITUTION:During engine driving, first of all, a suction absolute pressure signal Pm out of a suction pressure sensor 3 is taken into a control unit and compared with a first specified value, for example, 1,050mm.Hg at a first comparator device, and when Pm>=1,050mm.Hg is the case, an actuator 9 is made into an ON state by means of a first selector device, while a waste gate valve 8 is controlled in accordance with the suction absolute pressure. On the other hand, when it is of Pm>=1,050mm.Hg, the suction absolute pressure Pm is compared with a second specified value 1,000mm.Hg at a second comparator device, and when Pm<1,000mm.Hg is the case, the actuator 9 is made into an OFF state by means of a second selector device whereby the waste gate valve 8 is kept up in closure. With this constitution, the supercharging pressure at highland is boosted up and thereby dravability at the high land is well improved.

Description

DETAILED DESCRIPTION OF THE INVENTION Technical Field The present invention relates to an intake air pressure (supercharging pressure) control device for a supercharged internal combustion engine. Note that internal combustion engines include both gasoline engines and diesel engines.

Conventional technology In general, in a supercharged internal combustion engine, intake air is forcibly pressurized using the flow energy of exhaust gas and sent into the combustion chamber of the engine, but the supercharging pressure is set at a set value. A wastegate valve is provided in order to prevent the supercharging pressure from exceeding the maximum pressure and to improve the start-up characteristics of the supercharging pressure. This Westgelt valve operates according to the pressure difference between boost pressure and atmospheric pressure. That is,
When the pressure difference between the All exhaust gas passes through the turbocharger turbine.

However, in the conventional type described above, when the atmospheric pressure decreases, the pressure difference reaches a predetermined value even if the boost pressure is low, the wastegate valve is opened, and the boost pressure reaches the set value. It becomes. In particular, in diesel engines, when the intake pressure decreases, the fuel injection amount also decreases, so there is a problem in that drivability at high altitudes is significantly decreased.

Purpose of the Invention The purpose of the present invention is to solve the problems of the conventional type described above.
The wastegate valve is controlled by the intake pipe absolute pressure, and by keeping the wastegate valve closed until this absolute pressure exceeds a predetermined value, the boost pressure at high altitudes can be increased, making it possible to operate at high altitudes. It is about improving sexuality.

Structure of the Invention The structure of the present invention for achieving the above object is shown in FIG. In FIG. 1, a supercharged internal combustion engine to which the present invention is applied has a turbine 7a which is rotated by the engine's air gas. A blower 7b that sends exhaust gas into the combustion chamber, a wastegate valve 8 that bypasses the turbine,
Then, the intake absolute pressure associated with the actuator that operates the wastegate valve 8 is detected according to the pressure difference between the pressure of the pressurized intake air and the atmospheric pressure. The first comparison means compares the intake absolute pressure with a first predetermined value, and the second comparison means compares the intake absolute pressure with a second predetermined value.

At this time, the second predetermined value is set to be larger than the first predetermined value. As a result, when the intake absolute pressure becomes equal to or lower than the first predetermined value, the first 7' actuator switching means switches the actuator 9 from the on state to the off state; When the predetermined value is exceeded, the second actuator switching means switches the actuator 9 from the off state to the on state.

Example The present invention will be described in detail with reference to the drawings from FIG. 2 onwards.

FIG. 2 is an overall schematic diagram showing an embodiment of the intake air pressure control device for a supercharged internal combustion engine according to the present invention. In FIG. 2, an intake manifold 2 of an engine body 1 is provided with an intake pressure sensor 3 for detecting the absolute pressure of intake air, and this intake pressure sensor 3 generates an analog voltage signal in accordance with the absolute pressure.

4 is an intake pipe, 5 is an exhaust manifold, and 6 is an exhaust pipe.

Reference numeral 7 denotes a supercharger, which is composed of a turbine 7a rotated by exhaust gas discharged from the exhaust pipe 6, and a blower 7b mounted coaxially with the turbine 7a.

The wastegate valve 8 is provided to prevent the intake air pressure (supercharging pressure) from exceeding a set value and to improve the rising characteristics of the supercharging pressure. Reference numeral 9 denotes an actuator for the wastegate valve 8, which has a structure shown in FIG. That is, the waste gate valve 8 begins to open at F=F, -)-F.

However, F is the supercharging pressure in the first diaphragm chamber 91, F is the combined force of the diaphragm 92 and the spring 93,
□ F is the pressure inside the second diaphragm chamber 94, that is, the atmospheric pressure, when the following relationship is satisfied. Therefore, when the atmospheric pressure F decreases during high-altitude operation, the wastegate valve 8 begins to open at a small boost pressure F, but this is prevented in the present invention.

In order to prevent the above-mentioned reduction in supercharging pressure F, a three-way solenoid valve 11 is provided in the middle of an air passage 10 that connects the intake pipe 4 and the actuator 9.

When the solenoid valve 11 is turned on, an air passage is formed as shown by the arrow 11L, and conversely, when the solenoid valve 11 is turned off, an air passage is formed as shown by the arrow 11b. When the solenoid valve 11 is turned off, the pressure F in the first diaphragm chamber 91 of the actuator 9 becomes atmospheric pressure F, so the actuator 9 is turned off and the wastegate valve 8 opens. There isn't. In the present invention, when the supercharging pressure is low, the solenoid valve 11 is turned off and the actuator 9 is turned off, thereby preventing the supercharging pressure from decreasing at high altitudes.

The control circuit 12 controls the above-mentioned three-way solenoid valve 11 using an analog signal from the intake pressure sensor 3, and is implemented as a microcomputer, for example. Of course, this microcomputer also performs other controls such as fuel injection amount control and fuel injection timing control.

Next, the operation of the control circuit shown in FIG. 2 will be explained with reference to the flowchart shown in FIG. The interrupt step 401 starts at a predetermined time or every predetermined crank angle. In step 402, the intake pressure sensor 3 also takes in the absolute pressure Pm,
Next, in step 403, Pm≧1050 mHf
'l' (l) indicates whether or not.

If it is determined in step 403 that P ≧1050 If, then in step 404 it is determined whether the flag FL is 10". Here, the flag FL (-6i") indicates that the three-way solenoid valve 11 is on. state, that is, the actuator 9 is in the on state.

Therefore, if it is determined in step 404 that FL='
If it is determined that it is "O", flag FL is set in step 405, and then, in step 406, the three-way solenoid valve 11 is turned on to turn on the actuator 9.In other words, the actuator 9 is controlled by the pressure in the intake pipe 4. Therefore, it will be controlled 1.

When it is determined in step 403 that P<1050tanHf, the process proceeds to step 407, where it is determined whether flag FL="1".Flag FL="11"
If so, proceed to step 408 and Pm≦1000H2
Determine whether or not.

When it is determined in step 408 that Pm≦1000 asthma Hf, the flag FL is lowered in step 409, and then
In step 410, the three-way solenoid valve 405 is turned off to turn off the actuator 9.

On the other hand, if the determination result is negative at steps 407 and 408, the routine proceeds to step 411 and this routine ends. tb, in this case the operation of the actuator 9 is kept in the OFF state.

FIG. 5 is a characteristic diagram showing the operation according to the routine of FIG. That is, when the absolute pressure Pm of the intake pressure sensor 3 increases, the flag FL changes from '0' to '1' for the first time when Pm = 1 (150aHf), and therefore the operation of the actuator 9 changes to A. ) state to the on state. Conversely, when the absolute pressure Pm of the intake pressure sensor 3 decreases, the flag FL changes from '1' to '0#' for the first time when n1 = 10001 mHf, and therefore, The operation of the actuator 9 switches from the on state to the off state. Then, 1000ffllllHf(P (1050 gates H
In the range of f, the flag FL is held in its previous state, and therefore in the state before the line of motion of the actuator 9.

Such hysteresis operation is useful for preventing hunting of the actuator 9.

In addition, the above-mentioned 1. The second predetermined value is 1001000.
It goes without saying that the values of f, 1050 mnHf can be other values.

DETAILED DESCRIPTION OF THE INVENTION As described in detail, according to the present invention, the supercharging pressure at high altitudes can be increased and hunting operation can also be prevented, which is useful for improving drivability.

[Brief explanation of drawings]

Fig. 1 is an overall block diagram for explaining the present invention in detail, Fig. 2 is an overall schematic diagram showing an embodiment of the intake air pressure control device for a supercharged internal combustion engine according to the present invention, and Fig. 3 is an overall block diagram for explaining the present invention in detail. 2 is a detailed diagram of the actuator 9, FIG. 4 is a flowchart for explaining the operation of the control circuit 10 in FIG. 2, and FIG.
The figure is a diagram showing the operating characteristics according to the flowchart of FIG. 4. Engine body 3: Intake pressure sensor 7: Supercharger 7a: Turbine 7b Ni blower 8: Waste gate valve 9 Near actuator unique 11: Three-way solenoid valve 12: Control circuit. Patent applicant Toyota Motor Corporation Patent agent Akira Aoki Patent attorney Kazuyuki Nishidate Patent attorney Akira Yamaguchi Patent attorney Masaya Nishiyama Figure 3 91

Claims (1)

[Claims] 1. A turbine rotated by the exhaust gas of the internal combustion engine; a blower that rotates with the rotation of the turbine to pressurize intake air and send it into the combustion chamber of the engine; a wastegate valve that allows the exhaust gas to bypass the turbine; In the internal combustion engine with a supercharger, the engine includes an actuator that operates the wastegate valve according to a pressure difference between the pressure of the pressurized intake air and atmospheric pressure; absolute pressure detection means, first comparison means for comparing the intake absolute pressure with a first predetermined value, and second comparison means for comparing the intake absolute pressure with a second predetermined value greater than the first predetermined value. , a first actuator switching means for switching the actuator from an on state to an off state when the intake absolute pressure becomes equal to or less than the first predetermined value, and the intake absolute pressure is set to the 1d:) pJr.
An intake air pressure control device for an internal combustion engine with a supercharger, characterized in that a second seven-actuator switching means is provided for switching the actuator from an off state to an on state when the pressure exceeds a predetermined value.