JPH0310011B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a fail-safe device for an intercooler in a supercharged internal combustion engine having an intercooler.

[Conventional technology]

In a supercharged internal combustion engine such as a turbocharger or a supercharger, intake air is sent to the engine in a compressed state, so its temperature tends to increase. As the temperature increases, the air density decreases, the filling efficiency decreases, and the supercharging effect decreases. Therefore, an intercooler is installed downstream of the supercharger to lower the temperature of the intake air entering the engine.

If the intercooler is a water-cooled type, its cooling capacity will become insufficient due to a drop in the water level. In this case, the temperature of the intake air increases, making knocking more likely to occur. In other words, the ignition timing is set to be the optimum ignition timing when the intake air temperature is low enough for the intercooler to operate normally. Therefore, if the water level of the intercooler falls for some reason, the temperature of the intake air will increase compared to during normal operation, and the ignition timing will be over-advanced relative to the optimum timing, resulting in knocking. Therefore, Utsukai 58-73938
In order to provide a failsafe for the intercooler, the system detects the temperature difference between the intake air at the entrance and exit of the intercooler, and when this temperature difference becomes small, it is determined that there is an abnormality in the intercooler, and the amount of fuel injection is increased as a countermeasure against knocking. I'm going. That is, the aim is to lower the combustion temperature by increasing the amount of fuel injected, thereby suppressing knocking.

[Problem to be solved by the invention]

Conventional technology detects the difference in intake air temperature between the entrance and exit of the intercooler for fail-safe purposes. It is not an indicator. for example,
If the engine is started again with high residual heat after it has been stopped, or if the engine is idling after running under a high load, the engine compartment may become extremely hot or the intercooler may not have enough cooling water. Even if there is, the temperature difference between the entrance and exit of the intercooler will be considerably smaller than when the room temperature in the engine compartment is normal. This results in an erroneous determination that there is insufficient cooling water even though there is sufficient cooling water in the intercooler.

In addition, if there is an abnormality in the intercooler, conventional technology takes countermeasures by increasing the amount of fuel injection.
If you try to suppress knocking by simply increasing the fuel injection amount, you will not be able to suppress knocking unless you increase the amount by a large amount to the misfire limit. Therefore, instead of increasing the fuel injection amount, retarding the ignition timing may be considered as a normal means of suppressing knocking. However, in order to obtain an effective knocking suppressing effect, the retardation amount must be large, and in this case, there is a problem that the amount of unburned fuel in the exhaust system becomes large and the exhaust temperature increases due to afterburning.

An object of the present invention is to accurately control the engine while accurately knowing the presence or absence of cooling water in a water-cooled intercooler.

[Means to solve the problem]

According to this invention, as shown in FIG. 1, in an internal combustion engine with a supercharger A in which a water-cooled intercooler C is installed in an intake pipe B of the engine, a cooling water amount detection means for detecting a decrease in the amount of intercooler cooling water is provided. D; ignition timing retard means E for retarding the ignition timing by a predetermined amount when a decrease in the amount of intercooler cooling water is detected by the cooling water amount detection means D; and the predetermined amount is increased as the engine speed increases. An intercooler fail-safe device is provided, which includes: a retard amount setting means F for setting; and a means G for increasing the fuel injection amount as the retard amount increases according to the retard amount of ignition timing.

[Effect]

Cooling water amount detection means D detects a decrease in the amount of intercooler cooling water.

The ignition timing retardation means E retards the ignition timing by a predetermined amount when the cooling water amount detection means D detects a decrease in the amount of intercooler cooling water. The retard amount setting means F sets the predetermined amount to be larger as the engine speed is higher.

The fuel injection amount increasing means G increases the fuel injection amount according to the amount of retardation of the ignition timing, and the larger the retardation amount is.

〔Example〕

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

First, in Fig. 2, 1 is the main body of the internal combustion engine, 2
4 is a supercharger that uses the flow velocity of exhaust gas to turn a turbine 2a provided in an exhaust flow path 3a and supercharges intake air by a compressor 2b provided in an intake flow path 3b; 4 is a supercharger that cools the intake air; This is an intercooler that serves as an intake air cooling means. The intercooler 4 is a water-cooled type, and the compressor 2b of the supercharger 2
A heat exchange pipe 4a located in the intake passage 3b downstream of
, a condenser 4b located at the front of the vehicle where it is easily exposed to wind, and a cooling water circulation pump 4c.
The cooling water from the condenser 4b is transferred to the heat exchanger 4a.
It consists of a pipe 4d that introduces the cooling water from the heat exchanger 4a to the condenser 4b, and a pipe 4e that introduces the cooling water from the heat exchanger 4a to the condenser 4b. Reference numeral 6 represents a well-known waste gate valve that is provided in a bypass passage 8 that bypasses the turbine 2a and adjusts the supercharging pressure, and 10 represents an actuator that drives the waste gate valve 6 in accordance with the pressure in the intake passage 3b downstream of the compressor 2b. ing. Further, 12 is an igniter that generates high voltage in response to a control signal from the electronic control circuit 14, 16 is a distributor that distributes the high voltage to each cylinder of the gasoline engine 1 in synchronization with the crank angle, and 17 is a fuel distributor. The injection valves 18 each represent a spark plug that is attached to each cylinder head 20 and generates an electric spark to ignite the air-fuel mixture. Further, 21 is attached to the distributor 16, and the rotor 16a
In cooperation with the upper permanent magnet piece 16b, for example, 30°C
This is a rotation speed sensor that detects the rotation speed of the engine 1 by generating a pulse every time. Furthermore, 22 is the rotor 16
For example, 720°C in cooperation with the permanent magnet piece 16c of a.
This is a crank angle sensor that generates a pulse every A to discriminate between cylinders. 26 is an air flow meter that detects the flow rate of intake air. Further, 28 is a throttle sensor that detects the opening degree of the throttle valve 29. In this embodiment, a water level sensor 30 is used as a sensor for detecting the cooling capacity of the intercooler 4.
is provided to generate a signal corresponding to the level of cooling water in the heat exchanger 4a of the intercooler 4.

Next, the internal configuration of the electronic control circuit 14 will be explained. As shown in the figure, the electronic control circuit 14 includes a well-known 4-bit to 8-bit CPU 40, a memory 42 consisting of ROM and RAM, an input port 46, an output port 50, and an address data bus 51. The engine 1's ignition timing and fuel supply amount, as well as the water pump 4, are determined by inputting the rotational speed or the cooling capacity of the intercooler 4 according to the program described below, and according to the data or the calculation results based on the data.
It is configured to control c.

A non-volatile area (ROM) of the memory 42 stores a program for controlling the present invention. The contents of the program will be explained below using a flowchart. FIG. 3 shows a routine for determining a decrease in the cooling capacity of the intercooler and for controlling the operation of the intercooler, which is a time interrupt routine that is executed every fixed period of time, for example, every 25 milliseconds. First, in step 100, it is determined whether or not the intercooler cooling capacity has decreased. In this embodiment, when the water level is below a predetermined value based on the signal from the water level sensor 30, it is determined that the cooling capacity of the intercooler 4 has decreased. If Yes, proceed to 102 and set the fail flag FAIL to 1 (set); if No, proceed to 104 and set the fail flag FAIL to 0 (reset). From 104 when intercooler 4 is operating normally.
Proceeding to 106, it is determined whether or not the intercooler 4 is operating. For example, when it is determined based on the signal from the throttle sensor 28 that the accelerator pedal is being depressed, this is an intercooler operating condition. 106
If Yes, proceed to 108 and an operation command for the water pump 4c is issued from the output port 50.
c rotates. If the answer is No in 106, the process advances to 86 and the water pump 4c is stopped. When intercooler 4 malfunctions, it goes from 102 to 112 and after the abnormality is displayed, it goes to 110.
A command to stop the water pump 4c is issued.

FIG. 4 shows the ignition timing control routine.
This routine is a crank angle interrupt routine that enters execution at a predetermined crank angle of a particular point to be controlled. The crank angle at which to start execution of ignition control can be obtained by the crank angle signal every 30°C from the rotation speed sensor 21 and the crank angle signal every 720°C from the cylinder discrimination sensor 22. . First, at step 200, the load or its representative value, the intake air amount -
The basic ignition timing _θBASE is calculated by the combination of the rotational speed ratio Q/N and the rotational speed N. That is, as is well known, in the memory 42 there is a map of basic ignition timing θ _BASE combinations for the combinations of the intake air amount-rotational speed ratio Q/N and the rotational speed N, and the air flow meter 26
From the intake air amount Q and the rotational speed N actually measured by the rotational speed sensor 21, θ _BASE is calculated using a map.

In 202, intercooler 4 fail flag
It is determined whether FAIL is 1 or not. intercooler 4
When is normal (F=0), the process branches to No and proceeds to 204, where the ignition timing retardation correction amount Δθ is set to 0.

When intercooler 4 is abnormal, FAIL=1.
The determination in 202 is Yes, and the process proceeds to 206, where calculation of the ignition timing retardation correction amount Δθ at the time of failure is executed.
That is, as shown in Fig. 6, the correction is set so that the retardation amount becomes larger as the rotation speed increases with respect to the rotation speed N or the intake air amount - rotation speed Q/N ratio, and this relationship is representative. A map is stored in the memory 42, and the ignition timing retardation correction amount Δθ is calculated for the rotation speed N or the intake air amount-rotation speed ratio Q/N actually measured by the rotation speed sensor 21 and the air flow meter 26.

After calculating the ignition timing retard correction amount Δθ, in step 208, the ignition timing θ is determined as the basic ignition timing θ _BASE minus the correction amount Δθ and other correction amounts γ, which are not related to the present invention and will not be described. . At 210, an ignition signal is applied to the igniter 12 from the output port 50 so that it is ignited at the calculated ignition timing θ.

FIG. 5 shows a fuel injection routine, which is a crank angle interrupt routine that is executed every 360°C in the case of simultaneous injection, or at a predetermined crank angle of that cylinder in the case of individual cylinder injection. 300 shows the calculation of the basic injection amount τ _BASE . As is well known, the amount of intake air
τ _BASE is calculated by multiplying the rotation speed ratio Q/N by a predetermined coefficient K. In step 302, it is determined whether the fail flag FAIL is 1 or not. When intercooler 4 is normal (FAIL=0), it is judged as No,
In step 304, the failure correction coefficient K of the fuel injection amount is set to 1.0. When the intercooler 4 is abnormal, FAIL=1, 302 returns Yes, and the process proceeds to 306, where a map calculation of the correction coefficient K is performed. As shown in FIG. 7, the memory 42 has a map of the fuel injection amount increase correction coefficient K for the ignition timing retard correction amount Δθ at that time, and the ignition timing calculated at step 206 in FIG. The fuel increase correction coefficient K is calculated so that its value increases as the timing retardation correction amount Δθ increases. That is, in a region where the amount of retardation is large, the exhaust temperature tends to increase, so increasing the amount of fuel injection eliminates the increase in the exhaust temperature.

After calculating the correction coefficient K, the process moves to step 308, where the fuel injection time is calculated according to τ=τ _BASE ×K×α+β. Here, α is another correction coefficient whose explanation will be omitted since it is not directly related to this invention, and β is the correction amount. Next, at 310, a fuel injection signal is applied to the fuel injection valve 17 from the output port 50 so as to obtain the fuel injection amount τ thus calculated.

Furthermore, in the embodiment, the fuel injection amount increase correction coefficient K at the time of failure is corrected by the map according to the ignition timing retardation amount Δθ, but it is It is also possible to calculate a map.

Although the embodiments have shown a turbocharger type supercharger, the present invention is equally applicable to an intercooler for a mechanical type supercharger.

〔effect〕

By detecting the amount of cooling water in the intercooler, abnormalities in the intercooler can be accurately determined and appropriate fail-safe control can be performed.

In addition, by increasing the ignition timing retard amount as the engine speed increases when a fail is detected, and increasing the amount as the retard amount increases, it is possible to effectively suppress knocking during a fail while increasing the exhaust temperature. It is also possible to prevent this.

[Brief explanation of the drawing]

FIG. 1 is a configuration diagram of this invention. FIG. 2 is a configuration diagram of an embodiment. Figures 3 to 5 are flowcharts. Figure 6 is a map of the ignition timing retard correction amount. FIG. 7 is a map of fuel injection timing correction coefficients. 2...supercharger, 4...intercooler, 12...
...Igniter, 14...Control circuit, 16...Distributor, 17...Fuel injection valve, 18...
Spark plug, 30...water level sensor.

Claims (1)

[Scope of Claims] 1. In a supercharged internal combustion engine in which a water-cooled intercooler is installed in the intake pipe of the engine, there is provided a cooling water amount detection means for detecting a decrease in the amount of intercooler cooling water; an ignition timing retard means for retarding the ignition timing by a predetermined amount when a decrease in the amount of cooling water is detected; a retard amount setting means for setting the predetermined amount to be larger as the engine speed is higher; An intercooler failsafe device comprising: means for increasing the amount of fuel injection as the amount of retardation increases according to the amount of angle.