JPS6196128A - Method of controlling intake of diesel engine with supercharger provided with intercooler - Google Patents

Abstract

PURPOSE:To prevent an intercooler from intake cooling due to a heat exchanger and burning quality from degradation due to overcooling of intake by changing over an intake path even in warming up an engine when deceleration running is continuously carried out. CONSTITUTION:Intake introduced from an air cleaner 6 is pressurized by a supercharger 4 and introduced into an intake manifold 2 through a heat exchanger 7 of inter cooler and an intake path 8. In tie intake path 8 is provided a bypass path 9 for bypassing the heat exchanger 7 and both paths 8, 9 are changed over by a change-over valve 10. Then, the respective signals of an intake temperature sensor 14, rotational frequency sensor 15 and accelerator position sensor 16b are supplied to the input of a control computer 13. And when deceleration running is continuously carried out over a predetermined time determined by intake temperature, and actuator 12 is driven to change over the change-over valve 10 and pass intake through the bypass path 9 without passing through the heat each anger 7 for preventing the intake from overcooling.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an intake air control method for preventing excessive cooling of intake air in a supercharged diesel engine equipped with an intercooler.

[Conventional technology]

Conventionally, in order to prevent the intake air from being excessively cooled, the intake air was not allowed to pass through the heat exchanger of the intercooler during the warm-up period, and the intake passage was passed through the +l+71 alternative bypass passage. A device for preventing cooling of intake air has been proposed in Japanese Utility Model Application No. 57-53028. The purpose of the above rereading is to perform a good warm-up operation, and the intake passage is switched only depending on whether the Ennon is in a warm-up state or a cooling state. However, even if the diesel engine is warmed up, when deceleration operation is performed continuously for a long time, such as during long descents, the wall temperature of the combustion chamber decreases, and especially during deceleration operation, fuel cut occurs. In a diesel engine, if deceleration operation is performed continuously for a long period of time, the wall temperature of the combustion chamber will drop significantly.

Therefore, if light load operation or idling operation is performed immediately after continuous deceleration operation for a long time,
As the wall temperature of the combustion chamber decreases, the combustion condition of the diesel engine deteriorates, resulting in incomplete combustion due to misfire! There is a risk that unburned components such as HC and Co in the IP air will increase and white smoke will be generated.

Furthermore, in a diesel engine equipped with an intercooler, since an intake air cooling effect is added, the wall temperature of the combustion chamber further decreases during deceleration operation, which tends to lead to the deterioration of the combustion state as described above. ! There is.

[Problem that the invention seeks to solve, α]

The present invention aims to eliminate the above-mentioned problems,
Even when the engine is warmed up, if the engine is continuously operated at a reduced speed, the intake passage is switched to prevent the intake air from being cooled by the intercooler's heat exchanger. Provided is an intake air control method for a supercharged diesel engine equipped with an intercooler that prevents a decrease in combustibility, an increase in unburned components in the air, and the generation of white smoke. The purpose is to

[Means for solving problems]

Therefore, in the present invention, in addition to an intake passage from the supercharger to the engine via the intercooler heat exchanger, there is also a bypass passage from the supercharger to the ennon directly without going through the heat exchanger. The intake air control method for a diesel engine is provided with a switching valve that switches between the intake passage and the bypass passage, and the intake air Provided is an intake control method for a supercharged diesel engine equipped with an intercooler, characterized in that the switching valve is controlled so that the switching valve passes through the bypass passage.

〔Example〕

Embodiments of the present invention will be specifically described with reference to the drawings. FIG. 1 schematically shows the configuration of a diesel engine to which the present invention is applied. The tasel engine includes an intake manifold 2, an exhaust manifold 3, a supercharger 4, and an exhaust pipe 5. In addition to the intake passage 8 where the intake air introduced from the air cleaner 6 is pressurized to the supercharger 4 and guided to the intake manifold 2 via the heat exchanger 7 of the intercooler, there is also a bypass passage that does not pass through the heat exchanger 7. 9, the intake passage 8 and the bypass passage 9.
It is equipped with a switching valve 10 that switches between the two.

The switching valve 10 is coupled to an actuator 12 by a link 11. Actuator 12 consists of a linear solenoid and is controlled by control computer 13. The control computer 13 includes a signal (T) from an intake air temperature sensor 14 attached to the air cleaner 6, a signal (N) from a rotational speed sensor 15 that detects the rotational speed of the engine 1, and an accelerator pedal 2 that detects the operating position of the accelerator. The signal <a> of the sensor 16 is input. Control computer 13
determines whether or not the diesel engine is in deceleration operation based on the above input signal, and drives the actuator 12 if deceleration operation has been performed continuously for a predetermined time period determined by the intake air temperature. Then, the switching valve 10 is changed to fJJ, so that the intake air does not pass through the heat exchanger 7 and instead passes through the bypass passage 9.
to prevent overcooling of the intake air.

The actual processing within the control computer 13 that executes the above control idea will be explained according to the 70-chart in the t52 diagram.

The 70-chart shown in FIG. 2 is an intake control routine for switching the intake passage, and this routine starts when a 6-interrupt process 200 is started, which is executed at regular intervals, for example, every 0.2 seconds. , at step 201,
It is checked whether or not the warm-up operation has been completed. If the warm-up operation has been completed, the process proceeds to step 202; if not, the process proceeds to step 207.

Step 202 is executed when the warm-up operation is completed.

Diesel engine 1 has deceleration luck 11! A determination is made as to whether the Deceleration operation is determined by engine rotation WL
N and the amount of depression a of the accelerator pedal, and when the 7xel pneumatic sensor 16 detects that the accelerator pedal is released and the rotation speed of the diesel engine 1 is above a predetermined value, the rotation is determined. When it is detected by the multi-sensor 15, it is determined that deceleration operation is in progress, and in this case, the process proceeds to step 203. On the other hand, when the above-mentioned discrimination conditions are not satisfied, that is, in normal operation other than deceleration operation, the process proceeds to step 208.

Step 203 is executed during deceleration operation, and in this step 203, the count value C of the deceleration operation time counter is
is counted up by one. During deceleration operation, step 203 is always executed for each interrupt process at a fixed time interval, so the count value C corresponds to the deceleration operation time. After step 203, the process proceeds to step 204.

In step 204, the temperature (T) detected by the intake temperature sensor 14 is read.In step 205, a limit count value aSε is calculated from the detected intake temperature (T). The limit count value C3lET corresponds to the permissible duration of continuous operation during deceleration operation while taking in air via the heat exchanger 7 of the intercooler. This corresponds to the time until switching, and the limit count value C''SET and intake fiT have a relationship as shown in FIG.

The limit count value C3ET is calculated by searching the data m recorded in the storage element from the intake air temperature T and performing an interpolation calculation.

Next, in step 206, it is determined whether the deceleration operation time count value C is greater than the limit count value C3ET. When C≧C3ET, the deceleration operation is continued for longer than the allowable duration time, so
Proceed to step 207, and in step 207, drive the 7 cutter 12 to switch off the IF or 10 to 6 bypass passages 1
Switch to 139. When C≧C3ET is not satisfied, the deceleration operation time is within the allowable joint aunmatsu time, so step 209
Then, the switching valve 10 is switched to the intake passage via the heat exchanger 7.

During normal operation other than deceleration operation, the process proceeds to step 208. In step 208, the count value C of the deceleration time counter is reset to 0, and then the process proceeds to step 209.
The switching valve 10 is switched to the normal intake passage via the heat exchanger 7, and the interrupt processing routine is ended.

As described above, the interrupt processing routine based on the t'70-chart is executed at regular intervals, so that if deceleration operation continues for a predetermined period of time or more, the intake passage is switched to the bypass passage 9, and the intake air is The heat exchanger 7 prevents supercooling.

Do not suddenly switch the intake passage during deceleration operation,
The intake passage is switched only when the engine has been operated at deceleration continuously for a predetermined period of time calculated from the intake air temperature.
Since the switching frequency of the switching valve 10 can be kept to a minimum and there is no frequent switching of the intake passage during operation, switching of the intake passage becomes practical.

In the above-mentioned large embodiment, since the intake air temperature is detected at the position of the E-cleaner before supercharging, the intake air temperature fluctuates slowly and has the advantage of being easy to control.

By setting the intake air temperature detection position after the turbocharger and further after the intercooler heat exchanger and detecting the feed temperature after supercharging, the above permissible continuation is achieved until the intake passage is switched during deceleration operation. The time can be set to an allowable duration that corresponds more accurately to the wall temperature drop of the combustion chamber of the engine.

When the intercooler is a water-cooled intercooler, the intake air temperature is not directly detected, but the cooling water temperature of the water-cooled heat exchanger is detected, and 'I1 is calculated from the intake air temperature at the intake manifold estimated from the cooling water temperature. ．． It is possible to calculate the above-mentioned allowable continuation time during high-speed operation and switch the intake passage. Although this method can estimate the intake air temperature at the intake manifold with some degree of accuracy, the fluctuations in the detected coolant temperature are relatively slow, so the advantage is that temperature detection is relatively easy and control is easy. be.

In the embodiments and other methods described above, the intake passage is completely switched. However, the opening degree of the switching valve may be continuously controlled based on the above-mentioned intake air temperature and am time of deceleration operation. It goes without saying that it is possible.

〔Effect of the invention〕

As described above, the present invention prevents the intake air from being cooled by the heat exchanger of the intercooler even if the ennon is warmed up and is continuously operated at deceleration. It has the excellent effect of preventing a decrease in the temperature of the combustion chamber wall surface due to cooling, preventing deterioration of combustibility, and preventing an increase in unburned components in iI# gas or generation of white smoke.

[Brief explanation of the drawing]

The drawing shows an embodiment of the invention, 11'! Figure 1 is an overall configuration diagram, Figure 2 is a 70-chart explaining the construction J, tt
Figure S3 is a characteristic diagram of intake air temperature and limit count value. 1...Diesel engine, 4...t4 feed R, 6...
... Air cleaner, 7... Heat exchanger, 9... Bypass il path, 10... aV valve, 12... Actuator, 13... Control computer, 14... @ temperature sensor, 15... ...Recovery number sensor, 16...Accelerator bossion sensor. 1st mouth 2nd figure

Claims (1)

[Scope of Claims] 1. In addition to an intake passage from the supercharger to the engine via the heat exchanger of the intercooler, a bypass passage from the supercharger to the engine directly without passing through the heat exchanger is provided. and a switching valve for switching between the intake passage and the bypass passage, the method comprising: a switching valve for switching between the intake passage and the bypass passage; An intake air control method for a supercharged diesel engine equipped with an intercooler, characterized in that the switching valve is controlled so that intake air passes through the bypass passage. 2. The intake air control method for a supercharged diesel engine equipped with an intercooler according to claim 1, wherein the intake air temperature is an intake air temperature before supercharging. 3. The intake air control method for a supercharged diesel engine equipped with an intercooler according to claim 1, wherein the intake air temperature is an intake air temperature after supercharging. 4 The heat exchanger of the intercooler is a water-cooled heat exchanger, and the intake air temperature is an intake air temperature calculated from the cooling water temperature of the water-cooled heat exchanger. An intake air control method for a supercharged diesel engine equipped with an intercooler according to item 1.