JPH0212290Y2 - - Google Patents

Description

[Detailed Description of the Invention] <Technical Field> The present invention relates to a mixture control device for a turbocharged engine.

<Prior Art> In a turbocharged engine, the characteristics of fuel efficiency, torque, and exhaust temperature with respect to the mixture ratio of the air-fuel mixture when the accelerator is fully open (maximum intake air amount) are as shown in FIG. That is, the output is maximum at the mixture ratio at point A in the figure, and the engine performance can be maximized.

However, the exhaust temperature tends to increase as the mixture ratio becomes thinner due to the relationship with combustion speed, etc. Therefore, in reality, in order to prevent engine and turbine seizure, exhaust temperature is limited. A
It was necessary to use a location (point B in the diagram) where the mixture ratio was extremely rich compared to point A, and both the output and fuel efficiency were inferior to point A.

However, the increase in exhaust gas temperature actually becomes a problem only when the accelerator is kept fully open for a long time, and for a short time, there is no problem even if the mixture ratio is thinner than the conventional one. In normal use, the fully open accelerator rarely lasts for a long time, and therefore it is extremely unreasonable to fix the mixture ratio at a high concentration when the accelerator is fully open.

In order to solve these problems, there has conventionally been an air-fuel ratio control method as disclosed in Japanese Patent Laid-Open No. 58-28560.

When the exhaust gas temperature is above a predetermined temperature, the fuel injection amount per stroke is increased according to the temperature difference to supply a rich mixture to the engine, and when the exhaust gas temperature is higher than the predetermined temperature. When the temperature is low, the fuel injection amount is reduced according to the temperature difference to supply a lean mixture to the engine.

However, in this case, it is necessary to take the trouble to provide an exhaust gas temperature sensor for detecting the exhaust gas temperature, which is disadvantageous in terms of cost. Moreover, there is a problem in that accurate control cannot be performed unless sufficient responsiveness of the exhaust gas temperature sensor is ensured.

<Purpose of the invention> The present invention was created in view of the conventional problems, and uses a measuring means to measure the time after the full-open accelerator operation is detected by the full-open accelerator operation detection means, and uses this measured time to determine whether the exhaust gas is The objective is to provide a turbocharged engine that significantly improves output and fuel efficiency by predicting changes in gas temperature and controlling the mixture ratio in two stages when the accelerator is fully opened based on the predicted results. do.

<Structure of the invention> Therefore, as shown in FIG. 2, the present invention, in a turbocharged engine, includes a means for detecting full throttle opening, a means for measuring the elapsed time after the start of the operation detection, and a method for measuring with the measuring means. a mixture ratio control means for fully opening the accelerator, which controls the mixture ratio of the air-fuel mixture to be thinner than the mixture ratio limited by the exhaust temperature only at the initial stage of the fully open accelerator operation, and thereafter controls the mixture ratio to the mixture ratio limited by the exhaust temperature. The configuration is as follows.

<Example> Hereinafter, an example of the present invention will be described based on the drawings.

In FIG. 3 showing one embodiment, the ignition coil 1
From engine speed signal N and intake air amount measurement quantity 2
The intake air amount signal Q from N and Q is input to the basic pulse calculation circuit 3, and the basic pulse calculation circuit 3 calculates the basic injection amount Tp from N and Q so that the mixture ratio becomes λ=1.
is calculated, and an injection pulse signal having a pulse width corresponding to the calculated value is output. The full correction circuit 4 is supplied from a switch that detects the fully open position of the accelerator as the fully open accelerator operation detecting means of the present invention, for example, a full switch 5 that detects the fully open position of the throttle valve (an accelerator opening sensor, a boost pressure sensor, etc. may also be used). When a partial load is applied other than when the accelerator is fully open, the injection pulse from the basic pulse calculation circuit 3 is directly outputted to the drive circuit 6, and the drive circuit 6 drives the fuel injection valve 7, so that λ=1. The fuel injection amount is controlled as follows.

On the other hand, when the fully open position of the accelerator is detected by the full switch 5, the full correction circuit 4 uses the built-in counter function as a measuring means of the present invention to obtain a mixture ratio that maximizes the output for a predetermined period of time after the start of detection. Furthermore, after the predetermined time has elapsed, the injection pulse is corrected and outputted so as to obtain a rich mixture ratio limited by the exhaust temperature.

As a result, driving is performed with high output and low fuel consumption in the initial stage when the accelerator is fully open, so acceleration performance can be further improved, especially when the accelerator is fully open for a short time.
Additionally, fuel efficiency can be significantly improved. Furthermore, according to this configuration, the time after full throttle operation is detected by the fully open throttle position detection switch as the fully open throttle operation detection means is measured by the counter function as the measuring means, and the change in exhaust gas temperature is measured based on the measured time. Since the system predicts and controls the air-fuel mixture in the full throttle range in two stages based on the predicted results, there is no need to bother installing an exhaust gas temperature sensor to detect the exhaust gas temperature, which is advantageous in terms of cost. It is.

Moreover, the exhaust gas temperature sensor cannot perform accurate control unless its responsiveness is sufficiently ensured, but since the fully open accelerator is detected and controlled based on input without response delay from a fully open accelerator position detection switch, etc. , it has the advantage of being able to perform reliable control.

FIG. 4 and FIG. 5 show a flow chart and a time chart of the above embodiment, respectively.

<Effects of the invention> As explained above, according to the invention, after the start of full throttle operation, the mixture ratio is controlled to be thinner than the mixture ratio limited by the exhaust temperature for a predetermined period of time, so output and fuel efficiency can be maximized. Furthermore, by controlling the mixture ratio to be limited by the exhaust temperature after a predetermined period of time, excessive rise in exhaust temperature can be suppressed, and seizing of the engine, turbine, etc. can be sufficiently prevented. Effects can be obtained. In particular, the time after full throttle operation is detected by the full throttle operation detection means is measured by the measuring means, the change in exhaust gas temperature is predicted based on the measured time, and based on the predicted result, the mixture temperature in the full throttle range is determined. If the configuration is configured to control the temperature in two stages, there is no need to provide an exhaust gas temperature sensor, which is advantageous in terms of cost.Furthermore, the fully open state of the accelerator can be detected based on input without delay in response from the fully open accelerator operation detection means. The advantage is that reliable control can be carried out.

[Brief explanation of the drawing]

Fig. 1 is a diagram showing the characteristics of fuel efficiency, torque, and exhaust temperature with respect to the mixture ratio of a turbocharged engine, Fig. 2 is a block diagram showing the configuration of the present invention, and Fig. 3 is a diagram showing an embodiment of the present invention. FIG. 4 is a flowchart showing the control flow of the embodiment, and FIG. 5 is a time chart of the embodiment. 1...Ignition coil, 2...Intake air amount measuring device,
3...Basic pulse calculation circuit, 4...Full correction circuit, 5...Full switch, 6...Drive circuit, 7...
...Fuel injection rate.

Claims (1)

[Scope of utility model registration request] means for detecting full throttle operation; means for measuring time after the detecting means detects full throttle operation; and means for restricting the air-fuel mixture by exhaust temperature for a predetermined time after the start of full throttle operation measured by the measuring means. and a mixture ratio control means for fully opening the accelerator, which controls the mixture ratio to a mixture ratio thinner than that of the engine, and after a predetermined time has elapsed, controls the mixture ratio to a mixture ratio limited by the exhaust temperature. Mixture control device.