JPH05187236A - Control device for intercooler of diesel engine with exhaust turbosupercharger - Google Patents

Abstract

PURPOSE:To increase an output in a high load operation area and a high rota tion operation area and to improve the emission of exhaust gas in a low load and a low rotation operation area, in the case of a diesel engine. CONSTITUTION:In a diesel engine provided with an exhaust turbosupercharger formed such that an air-cooled or a water-cooled intercooler 12 is arranged in a supercharge tubular passage 11 from an exhaust turbosupercharger 6, an opening/closing valve 15 is located in an air introduction duct 13 to the intercooler 12 or a cooling water tubular passage. The opening/closing valve 15 is approximately fully opened in other operation area than low load and low rotation areas and opened and closed in such a way that temperature is adjusted to a value at which, in a low load and low rotation operation area, the temperature of intake air causes the decrease of both discharge amount of NOX and discharge amount of particulates.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention controls the cooling by the intercooler when cooling the supercharged air from the exhaust turbocharger with an intercooler in a diesel engine equipped with the exhaust turbocharger. It is related to the device.

[0002]

2. Description of the Related Art In general, the temperature of supercharged air compressed in an exhaust turbocharger is high, so that the charging efficiency of an internal combustion engine is reduced by the increase in temperature. Therefore, in order to prevent a decrease in charging efficiency due to this temperature rise, an intercooler is provided in the middle of the supercharging pipe line from the exhaust turbocharger to each cylinder of the internal combustion engine, and the supercooling is performed by this intercooler. It is well known that the air is cooled.

Further, conventionally, in an internal combustion engine having an exhaust turbocharger, as described in, for example, Japanese Utility Model Publication No. 62-20127, the exhaust turbocharger is connected to each cylinder of the internal combustion engine. In the supercharging pipeline to reach, by providing a bypass pipeline for the intercooler, in a low load and low rotation operating range of the internal combustion engine, and when the atmospheric temperature is low, the supercharging air from the exhaust turbocharger, By controlling so as to pass through the bypass pipe line, in a low load and low rotation operation range where the intake air amount is small, without reducing the charging efficiency in the high load operation range where the intake air amount is high and the high rotation operation range. It is configured to prevent supercooling of supercharged air.

[0004]

However, this control is
This is a simple ON-OFF control, and the temperature of the supercharged air that is taken into each cylinder of the internal combustion engine will vary considerably, as it rises and falls.
When this control is applied to a diesel engine, when the temperature of the supercharged air taken into each cylinder of the diesel engine is high, the combustion temperature in each cylinder becomes high, so the amount of NOx emission in the exhaust gas increases. Will be
Further, when the temperature of the supercharged air taken into each cylinder is low, the combustion temperature in each cylinder becomes low, so that the emission amount of particulates such as soot and the like in the exhaust gas increases. There is a problem that the emission decreases in the operating range of low load and low rotation.

According to the present invention, in a diesel engine, when the temperature of the intake air to each cylinder is low, the amount of particulates in the exhaust gas increases, and when the temperature of the intake air is high, the emission of NOx in the exhaust gas is high. Due to the relationship that the amount increases, the exhaust gas emission, the NOx emission amount, and the particulate emission amount can both be reduced at the temperature of the intake air (this state is called an optimum exhaust emission state). It is a technical subject to solve the above problem by utilizing this fact, paying attention to the existence of temperature.

[0006]

In order to achieve this technical object, the present invention comprises an air-cooled or water-cooled intercooler in the supercharging pipe line from the exhaust turbocharger to each cylinder. In a diesel engine with an exhaust turbocharger, an opening / closing valve is provided in the air introduction duct to the intercooler or the cooling water pipeline, while the opening / closing valve is set to approximately full open in an operating range other than low load and low rotation to reduce the load. And a control means for opening and closing so that the temperature of the intake air is a temperature at which both the discharge amount of NOx and the discharge amount of particulates can be reduced in the low rotation speed operation range.

[0007]

In this configuration, in an operating range other than low load and low rotation, the on-off valve provided in the air introducing duct to the intercooler or the cooling water introducing pipe is opened almost completely, so that the exhaust gas is exhausted. Since the supercharged air from the turbocharger can be sufficiently cooled, the efficiency of filling the diesel engine with air in the operating range other than low load and low rotation, that is, in the high load operating range and high rotational speed operating range. Can be improved.

On the other hand, in the low load and low rotation operating range, the temperature of the intake air to each cylinder is changed by the opening / closing operation of the opening / closing valve provided in the air introducing duct to the intercooler or the cooling water introducing pipe. Since the temperature is controlled so that both the NOx emission amount and the particulate emission amount can be reduced, the low load and low rotation operation range can be set to the optimum exhaust emission state.

Therefore, according to the present invention, it is possible to increase the output in the high load operating range and the high rotating speed operating range of the diesel engine, but to reduce the exhaust gas emission in the low load and low rotating speed operating range. It has the effect of being able to greatly improve.

[0010]

Embodiments of the present invention will now be described with reference to the drawings. In the figure, reference numeral 1 indicates a diesel engine including a plurality of cylinders, and the diesel engine 1 includes an intake manifold 2 for each cylinder and an exhaust manifold 3 for each cylinder.
It has and. Reference numeral 4 denotes a fuel injection pump for the diesel engine 1, and the fuel injection pump 4
Is equipped with an accelerator lever (not shown) for increasing or decreasing the fuel injection amount.

Reference numeral 6 denotes an exhaust turbocharger, which comprises an exhaust turbine 7 connected to the exhaust manifold 3 and a blower compressor 8 directly connected to the exhaust turbine 7. An intake line 10 from the air cleaner 9 is connected to the suction side of the blower compressor 8, and a supercharging line 11 to the intake manifold 2 is connected to the discharge side of the blower compressor 8. Has been done.

An air-cooling type intercooler 12 is provided in the middle of the supercharging pipe 11, and the intercooler 1 is provided.
A butterfly type on-off valve 15 which is opened and closed by an actuator 14 is provided in the air introduction duct 13 to the air conditioner 2. On the other hand, reference numeral 16 indicates a control circuit for the on-off valve 15, and the control circuit 16 detects the number of revolutions from the rotation sensor 17 for the diesel engine 1 and the rotation angle sensor 18 for the accelerator lever of the fuel injection pump 4. 2 and the intake air temperature from the temperature sensor 19 with respect to the intake air on the downstream side of the intercooler 12 in the supercharging pipe 11, the opening / closing valve 15 is operated as shown in the flowchart of FIG. It opens and closes via 14.

That is, in step S ₁ , the rotation speed N of the diesel engine 1, the rotation angle T of the accelerator lever 5, and the temperature (intake air temperature) t of the intake air to each cylinder t.
Then, in step S ₂ , the rotational speed N is compared with the medium speed Na corresponding to about 40% of the maximum rotational speed in the diesel engine 1, and the N is N
When it has not reached a, in step S ₃ , the rotation angle T of the accelerator lever is compared with the medium load rotation angle To corresponding to about 35% of the maximum rotation angle of the accelerator lever.

When N is equal to or greater than No, and T
When it is above To, that is, when the high-speed operation range and the high load range, the process proceeds to step S _4, to the opening operation of the on-off valve 15 to the fully opened. Meanwhile, the N is less than No, and, when T is less than To, that is, when the operation range of low load and low rotation, the process proceeds from step S ₃ to step S _5, where the intake air temperature t , If the intake air temperature t is not equal to the set temperature to, the process proceeds to the next step S ₆ , and if the intake air temperature t is lower than the set temperature to, the step S _{In 7} , the opening / closing valve 15 is closed by an appropriate angle θ to reduce the cooling performance in the intercooler 12 and raise the intake temperature t, while the intake temperature t is increased in step S ₆ . when not lower than the set temperature to, that is, when the intake air temperature t is higher than the set temperature to, in step S _8, by opening operation of the on-off valve 15 by appropriate angle theta, The cooling performance in the intercooler 12 is improved to lower the intake air temperature t, and when the intake air temperature t is equal to the set temperature to in step S ₅ , the open / close valve 15 is opened in step S ₉ .
The opening / closing valve 1
5 is opened and closed so that the intake temperature t becomes equal to the set temperature to.

In this configuration, the on-off valve 15 provided in the air introduction duct 13 to the intercooler 12 is fully opened in the operating range other than the low load and the low rotation, that is, in the high load operating range and the high rotation operating range. As a result, the supercharged air from the blower compressor 8 in the exhaust turbocharger 6 is
Since the cooling can be sufficiently performed, the efficiency of filling the diesel engine 1 with air can be improved in the high load operation range and the high rotation operation range.

In the low load and low speed operation range, the intake air temperature t for the diesel engine 1 can be controlled so as to reach the set temperature to as described above. By setting the temperature so that both the emission amount of NOx in the exhaust gas and the emission amount of particulates such as soot and smoke in the exhaust gas can be reduced,
The operation range of low load and low rotation can be set to the optimum exhaust emission state.

Although the above embodiment shows the case where the air-cooling type intercooler 12 is used, the present invention is not limited to this, and in the case of a water-cooling type intercooler, a cooling water pipe line for the intercooler is provided. It suffices to provide an on-off valve in the above, and to configure this on-off valve to open and close in the same manner as the above-mentioned embodiment.

[Brief description of drawings]

FIG. 1 is a diagram showing an embodiment of the present invention.

FIG. 2 is a diagram showing a flowchart of control.

[Explanation of symbols]

 1 Diesel Engine 2 Intake Manifold 3 Exhaust Manifold 4 Fuel Injection Pump 6 Exhaust Turbocharger 7 Exhaust Turbine 8 Blower Compressor 11 Supercharging Pipeline 12 Intercooler 13 Air Inlet Duct 14 Actuator 15 Open / Close Valve 16 Control Circuit 17 Rotation Sensor 18 Rotation angle sensor 19 Temperature sensor

Claims (1)

[Claims] 1. A diesel engine with an exhaust turbocharger, comprising an air-cooled or water-cooled intercooler in a supercharging pipe from the exhaust turbocharger to each cylinder. While an on-off valve is provided in the introduction duct or the cooling water pipeline, the on-off valve is almost fully opened in the operating range other than low load and low rotation, and the intake air temperature is NOx emission in the low load and low rotation operating range. A control device for an intercooler in a diesel engine with an exhaust turbocharger, which is provided with control means for opening and closing so that both the amount and the discharge amount of particulates can be reduced.