JPH06137156A - Supercharge pressure controller of internal combustion engine - Google Patents

Abstract

PURPOSE:To suppress decrease in operational performance of an engine and surely protect an engine from excessive supercharge regardless of distillation characteristic of fuel. CONSTITUTION:Characteristic of fuel supplied to a combustion chamber is detected by a fuel characteristic detection means 5, and distillation characteristic of the fuel is judged by a distillation characteristic judgement means 58 based on information from this fuel characteristic detection means 55, and supercharge pressure regulation means 31, 41 are controlled by a supercharge pressure correction means 59 based on the information from the distillation characteristic judgement means 58, and then the highest supercharge pressure is corrected to an appropriate value for the distillation characteristic of the fuel.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a supercharging pressure control device for an internal combustion engine, and more particularly to a supercharging pressure control device capable of supercharging control in consideration of fuel distillation characteristics.

[0002]

2. Description of the Related Art Supercharging pressure control is performed according to the properties of fuel,
A device with improved engine driving performance is disclosed in Japanese Patent Application Laid-Open No. 2-118.
No. 23 publication. In this device, duty control is performed on the opening of the pressure control valve according to the property (octane number) of the fuel supplied to the combustion chamber to obtain a supercharging pressure suitable for the property of the fuel, thus improving operating performance. I am trying to

[0003]

However, in an engine equipped with a supercharger, there is a problem that drivability is markedly different depending on the distillation characteristics of the fuel supplied to the combustion chamber. For example, in the case of fuel with a low boiling point (heavy fuel), the amount of fuel adhering to the wall surface of the intake port increases,
The air-fuel ratio (A / F) during each cycle is greatly disturbed. Therefore, the output performance when the throttle valve is fully opened is also deteriorated due to unstable combustion, and the transient response when the throttle valve is rapidly opened is also decreased.

In the case of a fuel (light fuel) having a large amount of low boiling point, since it has a good evaporation property, the amount adhering to the wall surface of the intake port is small, and the disturbance of the air-fuel ratio between cycles is small, so that stable combustion can be obtained. However, when the supercharging pressure is the same as that of heavy fuel, the supercharging state occurs, and the durability of the engine due to overpower and overresponse becomes a problem.

In the supercharging pressure control device of the above-mentioned Japanese Patent Laid-Open No. 2-11823, since the supercharging pressure is controlled independently of the distillation characteristic of the fuel, various fuels having different distillation characteristics are used. In this case, the above-mentioned problem occurs. Therefore, even when using various fuels with different distillation characteristics,
Supercharging pressure control that suppresses deterioration of operating performance and protects the engine from supercharging is desired.

The present invention focuses on the above-mentioned problems and suppresses the deterioration of the operating performance of the engine regardless of the distillation characteristics of the fuel, and furthermore, it is possible to reliably protect the engine from supercharging. An object of the present invention is to provide a pressure control device.

[0007]

A supercharging pressure control apparatus for an internal combustion engine according to the present invention for achieving the above object includes a supercharger for supercharging intake air supplied to a combustion chamber, and the supercharger. A supercharging pressure adjusting means for adjusting the maximum supercharging pressure of the intake air, a fuel property detecting means for detecting a property of fuel supplied to the combustion chamber, and a fuel property detecting means for detecting the property of the fuel based on information from the fuel property detecting means Distillation characteristic determining means for determining the distillation characteristic, and controlling the opening of the supercharging pressure adjusting means based on the information from the distillation characteristic determining means, the maximum supercharging pressure to a value suitable for the distillation characteristic of the fuel. And a supercharging pressure compensating means for compensating.

[0008]

In the supercharging pressure control device for the internal combustion engine thus configured, the property of the fuel supplied to the combustion chamber is detected by the fuel property detecting means, and the information from the fuel property detecting means is detected by the distillation characteristic determining means. Based on the above, the distillation characteristic of the fuel, that is, whether it is a light fuel or a heavy fuel is determined. When the distillation characteristic of the fuel is determined by the distillation characteristic determining means,
The supercharging pressure adjusting means controls the supercharging pressure adjusting means, so that the maximum supercharging pressure is corrected to a value which is most suitable for the distillation characteristic of the fuel.

Therefore, in the case of heavy fuel having a low low boiling point, the maximum boost pressure is corrected so as to be high.
Combustion is stabilized, and engine output drop and transient response drop due to air-fuel ratio disturbance are prevented. Also,
In the case of a light fuel having a large amount of low boiling point, the maximum supercharging pressure is corrected to be low, so that the engine can be reliably protected from the supercharging.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT A preferred embodiment of a boost pressure control device for an internal combustion engine according to the present invention will be described below with reference to the drawings.

FIGS. 1 to 4 show an embodiment of the present invention, particularly when applied to a 6-cylinder engine mounted on a vehicle. In FIG. 3, 1 is an engine body, 2 is a surge tank, and 3 is an exhaust manifold. Exhaust manifold 3 has no exhaust interference # 1- #
The cylinders are grouped into two groups of three-cylinder group and # 4 to # 6 cylinder group, and the collecting parts are communicated by a communication passage 3a. Reference numerals 7 and 8 denote a main turbocharger and a sub turbocharger arranged in parallel with each other. The turbines 7a and 8a of the turbochargers 7 and 8 are connected to the collecting portion of the exhaust manifold 3, and the compressors 7b and 8b are connected to the surge tank 2 via the intercooler 6 and the throttle valve 4.

The main turbocharger 7 is operated from the low intake air amount region to the high intake air amount region, and the sub turbocharger 8 is stopped in the low intake air amount region. In order to enable both the turbochargers 7 and 8 to operate and stop, the exhaust switching valve 1 is provided downstream of the turbine 8a of the auxiliary turbocharger 8.
7, an intake switching valve 18 is provided downstream of the compressor 8b. When both the intake and exhaust switching valves 18 and 17 are open, both turbochargers 7 and 8 are operated. The downstream side of the turbine 8a of the sub turbocharger 8 and the downstream side of the turbine 7a of the main turbocharger 7 can communicate with each other via an exhaust bypass passage 40. The exhaust bypass passage 40 is provided with an exhaust bypass valve 41 that opens and closes the exhaust bypass passage 40. Exhaust bypass valve 41
Are opened and closed by a diaphragm actuator 42.

A check valve 12 is provided in a bypass passage communicating between the upstream side and the downstream side of the intake switching valve 18, and when the intake switching valve 18 is closed, the compressor outlet pressure on the side of the auxiliary turbocharger 8 is the main turbo. When it becomes larger than the charger 7 side, air can flow from the upstream side to the downstream side. In the figure, 14 indicates an intake passage on the compressor outlet side, and 15 indicates an intake passage on the compressor inlet side.

The intake passage 15 is connected to an air cleaner 23 via an air flow meter 24. The front pipe 20 forming the exhaust passage is connected to the exhaust muffler via the exhaust gas catalyst 21. The intake switching valve 18 is opened and closed by the actuator 11, and the exhaust switching valve 17 is opened and closed by the diaphragm actuator 16. The waste gate valve 31 is adapted to be opened and closed by the actuator 9.

A pressure storage tank (positive pressure tank) 51 is connected to the intake passage between the compressor downstream of both turbochargers 7 and 8 and the intercooler 6, as shown in FIG. The accumulator tank 51 is provided with a check valve 51a for accumulating only positive pressure.

The actuators 9, 11, 16, 42 are
It is activated by the introduction of supercharging pressure. Each actuator 9, 11, 16, 42 has an accumulator tank 5
In order to selectively switch the supercharging pressure from 1 and the atmospheric pressure from the downstream of the air flow meter 24, the first, fourth, fifth and sixth solenoid valves 25, 28, 32, 44 are connected. ing. Switching of each solenoid valve 25, 28, 32, 44 is performed according to a command from the engine control computer 29.

When the first solenoid valve 25 is turned on, the intake switching valve 1
Actuating the actuator 11 so that 8 is fully opened,
When OFF, the actuator 11 is operated so that the intake switching valve 18 is fully closed. When the fourth solenoid valve 28 is turned on, the actuator 16 is operated so as to fully open the exhaust gas switching valve 17, and when it is turned off, the actuator 16 is operated so as to fully close the exhaust gas switching valve 17.

The fifth solenoid valve 32, which introduces atmospheric pressure into the actuator 42 that operates the exhaust bypass valve 41, is
Duty control is performed instead of N and OFF control. Similarly, the sixth solenoid valve 44, which guides the negative pressure to the actuator 9 that operates the wastegate valve 31, is turned on and off.
The duty is controlled instead of the control. As is well known, the duty control is to control the energization time by the duty value, and the average current is variably controlled in an analog manner by digitally changing the ratio of energization and non-energization.

The opening degree of the exhaust bypass valve 41 is changed by changing the bleed amount (leak amount) of the supercharged air introduced into the diaphragm chamber of the actuator 42 to the atmosphere by the duty control of the fifth solenoid valve 32. It is possible. The opening of the waste gate valve 31 can be changed by changing the bleed amount (leak amount) of the supercharged air introduced into the diaphragm chamber of the actuator 9 to the atmosphere by duty control of the sixth solenoid valve 44. ing.

When only one main turbocharger 7 is supercharged, the maximum supercharging pressure is adjusted by controlling the opening degree of the exhaust bypass valve 41. When two turbochargers in which both the main turbocharger 7 and the sub-turbocharger 8 are supercharged, the maximum supercharging pressure is adjusted by controlling the opening of the wastegate valve 31. The maximum supercharging pressure by the exhaust bypass valve 41 and the maximum supercharging pressure by the waste gate valve 31 are set to the same value.

FIG. 3 shows a system diagram of the engine centering on the evaporated fuel control device. In the figure, 61 indicates a fuel tank mounted on the vehicle. The evaporated fuel generated in the fuel tank 61 is guided to the charcoal canister 63 via the passage 62. As is well known, the charcoal canister 63 is an adsorption container for evaporated fuel containing activated carbon, and the evaporated fuel from the fuel tank 61 is temporarily adsorbed on the activated carbon of the charcoal canister 63. The charcoal canister 63 is connected to two purge passages, a main purge passage 64 and a sub purge passage 65.

The downstream end of the sub-purge passage 65 is connected upstream of the compressor 7b of the main turbocharger 7. The downstream end of the main purge passage 64 has two passages 64.
It is branched into a and 64b. One passage 64a is connected to the downstream side of the throttle valve 4, and the other passage 64b is connected.
Is connected upstream of the throttle valve 4. A purging electromagnetic valve 70 is provided in the middle of one passage 64a, and a check valve 71 is provided in the other passage 64b. The purge solenoid valve 70 has a function of controlling the purge amount of the evaporated fuel flowing through the main purge passage 64 by changing the duty ratio by the engine control computer 29.

A fuel temperature sensor 56 for detecting the temperature of the fuel F in the fuel tank 61 is attached to the fuel tank 61. Fuel tank 61 and charcoal canister 63
A paper flow rate sensor 57 that detects the flow rate of the evaporated fuel F ₁ is provided in the passage 62 that connects to and. The signals from the fuel temperature sensor 56 and the vapor flow rate sensor 57 are
It is input to the engine control computer 29. Fuel temperature sensor 56 and vapor flow rate sensor 57
Is the fuel F supplied to the combustion chamber 1a, as shown in FIG.
The fuel property detecting means 55 for detecting the property of is formed.

As shown in FIG. 3, the engine body 1 has an exhaust gas recirculation device (hereinafter simply referred to as “EGR device”) 81.
Is provided. The EGR device 81 includes an exhaust gas recirculation passage (EGR passage) provided between the exhaust system and the intake system.
82 is provided. The EGR passage 82 is for taking out a part of the exhaust gas from the exhaust system and recirculating it to the intake system, that is, recirculating it. As shown in FIG. 3, the EGR passage 8
The second outlet is connected to the exhaust port of the # 6 cylinder.
A part of the exhaust gas taken out from the exhaust port of the # 6 cylinder is recirculated to the surge tank 2 through the EGR passage 82.

An EGR valve 84 is provided in the middle of the EGR passage 82.
Is provided. The exhaust pressure chamber of the EGR valve modulator 91 and the constant pressure chamber of the EGR valve 84 are communicated with each other via the exhaust pressure passage 93, and the exhaust pressure applied to the constant pressure chamber acts on the exhaust pressure chamber. The EGR valve modulator 91 uses the EG
The introduction of atmospheric pressure to the negative pressure port is throttled in proportion to the exhaust pressure applied to the R valve 84, whereby the operating pressure applied to the diaphragm chamber of the EGR valve 84 is increased and adjusted. .

The negative pressure port of the EGR valve modulator 91 can communicate with the inside of the surge tank 2 located downstream of the throttle valve 4 via the negative pressure passage 89. In the negative pressure passage 89, a check valve 100 and a vacuum switching valve (VSV) 98 composed of a two-way solenoid valve are provided in series. Check valve 100 is a 2-way VSV
It is arranged closer to the negative pressure introducing port of the surge tank 2 than 98. The check valve 100 has a function of allowing only the flow of intake air flowing into the surge tank 2.

The VSV 98, which is a two-way solenoid valve, is duty-controlled by a command signal from the engine control computer 29 to obtain an opening amount according to the duty ratio. In the state where the VSV 98 is opened by the duty control, the negative pressure in the surge tank 2 passes through the negative pressure port of the EGR valve modulator 91 and becomes EG.
It acts on the diaphragm chamber of the R valve 84 to open the EGR valve 84.

Engine control computer 29
Is electrically connected to various operating condition detection sensors of the engine, and signals from the various sensors are input. The engine operating condition detection sensor includes an intake pipe pressure sensor 30, a throttle opening sensor 5, an air flow meter 24 as an intake air amount measuring sensor, an engine speed sensor 50, and an oxygen sensor 19. The engine control computer 29 includes a central processor unit (CPU) for performing calculations, a read-only memory (ROM) that is a read-only memory, a random access memory (RAM) for temporary storage, and an input / output interface (I
/ O interface) and an A / D converter for converting analog signals from various sensors into digital quantities.

As shown in FIG. 1, the engine control computer 29 is provided with a distillation characteristic judging means 58. Signals from the fuel temperature sensor 56 and the vapor flow rate sensor 57, which constitute the fuel property detection means 55, are input to the distillation characteristic determination means 58. The distillation characteristic judging means 58 is composed of a program stored in the engine control computer 29.

The distillation characteristic discriminating means 58 has a function of discriminating the distillation characteristic of the fuel F supplied from the fuel tank 61 based on signals from the fuel temperature sensor 56 and the vapor flow rate sensor 57 constituting the fuel property detecting means 55. Have That is, the distillation characteristic determining means 58 determines whether the fuel is a heavy fuel having a low boiling point, a light fuel having a high boiling point, or an intermediate fuel between the heavy fuel and the light fuel. ing.

When the temperature of the fuel F in the fuel tank 61 detected by the fuel temperature sensor 56 is low and the flow rate of the evaporated fuel F ₁ detected by the vapor flow rate sensor 57 is large, the distillation characteristic determining means 58 is used. Is a light fuel, and conversely, when the temperature of the fuel F is high and the flow rate of the evaporated fuel F ₁ is small, it is determined to be a heavy fuel.

The determination result of the distillation characteristic determination means 58 is input to the supercharging pressure correction means 59. The supercharging pressure correction means 59 is the engine control computer 2
9 is stored in the program. The supercharging pressure correction unit 59 has a function of correcting the maximum supercharging pressure based on the information from the distillation characteristic determining unit 58.

The supercharging pressure correcting means 59 is an exhaust bypass valve 41 as a supercharging pressure adjusting means when one turbocharger is used.
The maximum supercharging pressure is controlled by controlling the opening of the wastegate valve 31 as the supercharging pressure adjusting means when the two turbochargers are used to control the maximum supercharging pressure. ing.

The supercharging pressure correcting means 59 sets the supercharging pressure to Ymm when the determination result of the distillation characteristic determining means 58 is heavy fuel.
The maximum supercharging pressure is XmmHg (for example, 50 mm) when the judgment result of the distillation characteristic judging means 58 is light fuel.
It is designed to be reduced to 0 mmHg). When the determination result of the distillation characteristic determination unit 58 is the fuel located between the heavy fuel and the light fuel, the supercharging pressure correction unit 59 controls the maximum supercharging pressure to be ZmmHg (for example, 550 mmHg).

Next, the operation of this embodiment will be described. In the high intake air amount region, both the intake switching valve 18 and the exhaust switching valve 17 are opened and the intake bypass valve 10 is closed. As a result, the two turbochargers 7 and 8 are driven, a sufficient amount of supercharged air is obtained, and the output is improved.
In the low speed range and at the time of high load, both the intake switching valve 18 and the exhaust switching valve 17 are closed and the intake bypass valve 33 is opened. This drives only the main turbocharger 7. The reason why one turbocharger is used in the low intake air amount region is that the one turbocharger supercharging characteristic is superior to the two turbocharger supercharging characteristic in the low intake air amount region. By using one turbocharger, the boost pressure and the rise of torque are accelerated, and the response is prompt.

When shifting from the low intake air amount region to the high intake air amount region, that is, when switching from one turbocharger operation to two turbocharger operation, the intake switching valve 18
By controlling the exhaust bypass valve 41 to a small opening by duty control while the exhaust switching valve 17 is closed, the running speed of the auxiliary turbocharger 8 is increased and switching of the turbocharger is made smoother (shock during switching). Can be made smaller).

FIG. 2 shows a processing procedure of supercharging pressure control in the engine control computer 29. The control process is started in step 101 of FIG.
6 is detected. That is, in step 102, the temperature of the fuel F in the fuel tank 61 is detected by the fuel temperature sensor 56, and the flow rate of the evaporated fuel F ₁ flowing into the charcoal canister 63 is detected by the vapor flow rate sensor 57.

When the property of the fuel is detected in step 102, the process proceeds to step 103, and the distillation characteristic determining means 58 determines the distillation characteristic of the fuel F in the fuel tank 61. In step 103, it is first determined whether the fuel in the fuel tank 61 is a light fuel. If it is determined that the fuel is light fuel, the process proceeds to step 104,
It is determined whether or not it is a supercharging condition. When it is determined in step 104 that the supercharging condition is satisfied, step 10
5, the maximum boost pressure is Xm by the boost pressure correction means 59.
Set to mHg. When it is determined in step 104 that the supercharging condition is not satisfied, the process proceeds to step 111,
To return.

When it is judged in step 103 that the fuel is not a light fuel, the routine proceeds to step 106, where the distillation characteristic judging means 58 judges whether or not the fuel F in the fuel tank 61 is a heavy fuel. Here, when it is determined that the fuel F is the heavy fuel, the routine proceeds to step 107, where it is determined whether or not the supercharging condition is satisfied. In step 107,
When it is determined that the supercharging condition is satisfied, the routine proceeds to step 108, where the supercharging pressure correction means 59 sets the maximum supercharging pressure to YmmH.
set to g. When it is determined in step 107 that the supercharging condition is not satisfied, the process proceeds to step 111 and returns.

In step 106, when it is judged by the distillation characteristic judging means 58 that the fuel is not a heavy fuel, the routine proceeds to step 109, where it is judged whether or not it is a supercharging condition. If it is determined that the supercharging condition is satisfied, step 1
10, the maximum supercharging pressure is Zm by the supercharging correction means 59.
Set to mHg. When it is determined in step 109 that the supercharging condition is not satisfied, the process proceeds to step 111,
To return.

When the maximum boost pressure suitable for the distillation characteristic is set by the boost pressure correction means 59, in the case of the two turbocharger, the sixth solenoid valve 44 is controlled by the duty ratio according to the set pressure. The opening degree of the West Gale valve 31 is feedback-controlled so as to match the set maximum boost pressure. In the case of the single turbocharger, the fifth solenoid valve 32 is controlled by the duty ratio according to the set pressure instead of the sixth solenoid valve 44, and the opening degree of the exhaust bypass valve 41 is set to the maximum excess. Feedback control is performed to match the supply pressure.

In this way, when it is determined that the fuel F in the fuel tank 61 supplied to the combustion chamber 1a is a light fuel having a large amount of low boiling point, the maximum supercharging pressure is XmmHg (500
mmHg), so the supercharging state is resolved,
The durability of the engine can be improved, and shocks due to pre-ignition and supercharging can be prevented.
When it is determined that the fuel F in the fuel tank 61 is a heavy fuel with a low boiling point, the maximum boost pressure is YmmHg.
Since it is increased to (600 mmHg), combustion is stabilized, and output and response can be improved.

In this embodiment, the fuel property detecting means 55 including the fuel temperature sensor 56 and the vapor flow rate sensor 57 is used as the means for detecting the property of the fuel F, but the evaporated fuel F ₁ generated from the fuel tank 61 is used. It is also possible to adopt a configuration that uses a method of detecting the pressure of the above, a method of detecting the internal pressure of the fuel tank 61, an air-fuel ratio learning value method, or the like.

Further, in the present embodiment, the case where it is applied to the two-stage twin turbo engine has been described, but the present invention is not limited to this, and can be applied to an engine having one supercharger.

[0045]

According to the present invention, the following effects can be obtained.

(1) The property of the fuel supplied to the combustion chamber is detected by the fuel property detecting means, the distillation characteristic of the fuel is judged by the distillation characteristic judging means on the basis of the information from the fuel property detecting means, and the distillation characteristic is determined. The supercharging pressure adjusting means is controlled by the supercharging pressure compensating means based on the information from the discriminating means, so that the maximum supercharging pressure is corrected to a value suitable for the distillation characteristics of the fuel. In the case of fuel, the maximum supercharging pressure can be increased, and in the case of light fuel having many low boiling points, the maximum supercharging pressure can be reduced.

(2) Therefore, in the case of heavy fuel, even if the air-fuel ratio is disturbed by the adherence of fuel to the wall surface of the intake port,
Combustion can be stabilized by increasing the boost pressure, and output reduction and transient response reduction can be prevented. Further, in the case of light fuel, overpower due to supercharging is eliminated, and the durability of the engine can be improved.

(3) Since the excessive response due to overcharging is eliminated, it is possible to suppress the occurrence of shock due to acceleration / deceleration, and it is possible to improve the durability reliability of drive system parts other than the engine by alleviating the shock. it can.

[Brief description of drawings]

FIG. 1 is a block diagram of a boost pressure control device for an internal combustion engine according to an embodiment of the present invention.

FIG. 2 is a flow chart showing a processing procedure of supercharging pressure control by the apparatus of FIG.

3 is a schematic configuration diagram of an internal combustion engine in which the apparatus of FIG. 1 is used.

4 is a system diagram showing a piping connection relationship between each valve and an actuator used for supercharging pressure control in the internal combustion engine of FIG.

[Explanation of symbols]

1 Engine Main Body 1a Combustion Chamber 7 Main Turbocharger 8 Sub Turbocharger 31 Wastegate Valve as Supercharging Pressure Adjusting Means 41 Exhaust Bypass Valve as Supercharging Pressure Adjusting Means 55 Fuel Property Detecting Means 56 Fuel Temperature Sensor 57 Vapor Flow Rate Sensor 58 Distillation characteristic determination means 59 Supercharging pressure correction means F fuel F ₁ evaporated fuel

Claims (1)

[Claims] 1. A supercharger for supercharging intake air supplied to a combustion chamber, supercharging pressure adjusting means for adjusting a maximum supercharging pressure of intake air by the supercharger, and fuel supplied to the combustion chamber. Fuel property detection means for detecting the property of the fuel, distillation characteristic determination means for determining the distillation characteristic of the fuel based on the information from the fuel property detection means, and supercharging based on the information from the distillation characteristic determination means. A supercharging pressure control device for an internal combustion engine, comprising: a supercharging pressure correction unit that controls the pressure adjusting unit to correct the maximum supercharging pressure to a value suitable for the distillation characteristic of the fuel.