JPS6145051B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an exhaust recirculation control device for a diesel engine, and more particularly to an exhaust recirculation control device for a diesel engine equipped with an intake throttle device for reducing engine idle noise and vibration. It is.

Exhaust gas recirculation devices, also known as EGR devices, extract exhaust gas from the engine's exhaust system and recirculate it to the intake system to suppress the production of nitrogen oxides (NOX). It is used in many engines.

However, few EGR devices are still in practical use for diesel engines. One reason for this is that when the engine is idling, there is almost no difference in pressure between intake and exhaust air, making it difficult to control the EGR device.

On the other hand, the intake throttle device is, for example,
As provided by the applicant in No. 117441, etc., an intake throttle valve is provided in the intake system of a diesel engine, and this valve is closed during idling to restrict the intake air into the combustion chamber, thereby reducing the flow of air within one cycle. The purpose is to reduce torque fluctuations and reduce vibration and noise.

With this intake throttle device, if the intake air is throttled too much, combustion will become unstable and hydrocarbon components in the exhaust gas will increase. For this reason, the negative pressure downstream of the throttle valve is extracted, and this feeds back to actuate a transducer to adjust the negative pressure acting on the power motor for actuating the intake throttle valve; There is also one in which the intake pipe negative pressure is kept constant.

Also, Japanese Patent Application Laid-open No. 141826/1983 and Utility Model Application No. 54-
Publication No. 37723 describes an exhaust gas recirculation control device for a diesel engine that is equipped with an intake throttle device similar to the above-mentioned intake throttle device, but since the intake throttle valve (air control valve) operates in the entire engine load range, The intake air is throttled even in operating ranges other than idling, which may reduce the engine's intake efficiency and output.

The present invention focuses on the fact that a certain negative pressure is generated downstream of the intake throttle valve in the intake pipe during idling of a diesel engine equipped with the above-mentioned intake throttle device with a feedback mechanism.
Regarding the exhaust gas recirculation control device, which was conceived to be used to control EGR equipment, its purpose is to:
An exhaust gas recirculation control device that enables exhaust gas recirculation during idling, which was conventionally impossible, and does not restrict the intake air even in operating ranges other than idling, so there is no risk of reducing the engine's intake efficiency and output. It is not intended to be provided.

The gist of the present invention to achieve the above object is to provide an intake throttle device with a feedback mechanism that throttles the intake air to a constant negative pressure by an intake throttle valve disposed in the intake pipe only when idling, and a rotation sensor that throttles the intake air to a constant negative pressure only when idling. and an EGR device that detects the engine load and rotation speed using a fuel pump position switch, connects the negative pressure source higher than the negative pressure, and operates the EGR valve, and connects the diaphragm chamber of the EGR valve to the intake throttle valve. It is located in the exhaust recirculation control device of the diesel engine connected downstream.

To explain in detail one embodiment of the present invention shown below, in FIG. 1, 1 is a diesel engine, 2 is its intake pipe, 3 is its exhaust pipe, and EGR
It includes a device 4 and an intake throttle device 6.

The EGR device 4 is located between an extraction pipe 41 connected to the exhaust pipe 3 and a return pipe 42 connected to the intake pipe 2.
An EGR valve 43 is provided, and when negative pressure is introduced into the diaphragm chamber 44 from a vacuum tank 8 via a delay valve 45 and a control valve 46, the needle 47 is pulled up and the extraction pipe 41 and a return pipe 42 are communicated with each other so that exhaust gas recirculation can be achieved.

The intake throttle device 6 includes an intake throttle valve 61 disposed in the intake pipe 2, connects the throttle valve 61 and a power motor 62 through a link 63, and has a control valve 65 in its diaphragm chamber 64. The intake throttle valve 61 is configured to close when the negative pressure in the vacuum tank 8 is introduced through the throttle valve 61, and a transformer operated by the intake pipe negative pressure is provided in the intake pipe 2 downstream of the throttle valve 61. It has a deuser 66, which introduces atmospheric air through an attached filter according to the negative pressure, adjusts the negative pressure acting on the diaphragm chamber 64, and feedback-controls the opening degree of the throttle valve 61. Intake pipe negative pressure, e.g. 200mmHg
The structure is such that it can be maintained at a constant value.

For such an intake throttle device 6, the EGR
The device 4 opens the return pipe 42 to the intake pipe 2 downstream of the intake throttle valve 61, and also controls the intake pipe negative pressure in the intake pipe 2 downstream of the intake throttle valve 61 through the check valve 48 and the pipe 49. It is configured such that it can be transmitted to the diaphragm chamber 44.

The control valve 46 and the control valve 65 are valves with similar functions, and when a signal is applied to the coil C, they turn black to black and direct the negative pressure of the barqueum tank 8 to the diaphragm chambers 44 and 64. introduced,
When no voltage is applied, the light becomes white-white, and the atmosphere is communicated with the diaphragm chambers 44 and 64 through the filter F. Application of a signal to this coil C is controlled by a controller 9.

Further, 5 is a rotation sensor attached to the fuel injection pump 51, and 7 is a position switch that detects the opening degree of the fuel lever 52 of the same pump.
Alternatively, a signal from the rotation sensor 5 is input to the controller 9. As shown in FIG. 2, the control valve 65 is turned on to operate the power motor 64 only when the engine speed S is, for example, 800 rpm or less and the fuel lever opening L is in the range of, for example, 0 to 5 degrees. control valve 46
is when the engine speed S is 800 to 1800 rpm and the fuel lever opening L is 5 to 15 degrees.
Opens at 1800 rpm or more and at 15 to 20 degrees.
The controller 9 is set to fully open the EGR valve 43.

Further, in the EGR valve 43, when negative pressure (for example, 400 to 500 mmHg) in the vacuum tank 8 is introduced other than when idling, the needle 47 is fully opened at the maximum lift, and when the EGR valve 43 is idling, the intake throttle device The needle 47 is set so that it is slightly lifted even when a weak negative pressure of about 200 mmHg is applied, such as when the needle 47 is activated.

In the figure, 91 is the battery, and 68 is the intake throttle valve 6.
This is the first stop.

In the exhaust recirculation control device of the present invention having the above configuration, as described above, the intake throttle valve 61 is closed under preset engine operating conditions, and the effect of the intake throttle device 6 is exhibited.
The EGR valve 43 can also be fully opened under various conditions to achieve exhaust gas recirculation, and even during idling, exhaust gas recirculation can be achieved by utilizing the negative pressure in the intake pipe generated by the intake throttle device 6. .

That is, the intake throttle device 6 normally operates during idling, and at this time, the power to the control valve 46 is cut off, and the EGR device 4 does not normally operate. Alternatively, even if the EGR valve 43 is opened, there is no pressure difference between intake and exhaust during idling, so exhaust recirculation will not occur. However, the diaphragm chamber 44 in the present device communicates with the intake pipe 2 downstream of the intake throttle valve 61 via the pipe 49, and the intake throttle device 6 operates as described above to close the throttle valve 61. The opening degree of the valve is determined by the transducer 66.
Since the negative pressure in the intake pipe is maintained constant due to the feedback function of Thus, proper exhaust gas recirculation is achieved.

Of course, by using the intake throttle device 6 in this way,
The EGR device 4 operates only when the engine is idling; under other engine operating conditions, a delay valve 45 or a check valve 48 is provided to prevent inconvenience in the operation of the EGR device 4 and the intake throttle device 6. There is.

When not idling, the rotation sensor 5
Then, in response to a signal from the position switch 7, the control valve 46 is opened via the controller 9 as shown in FIG. 2, and the EGR valve 43 of the EGR device 4 is fully opened, so that more exhaust gas is recirculated.

As described above, according to the present invention, the exhaust gas recirculation control during idling uses the intake pipe negative pressure generated by the operation of the intake throttle device 6 as a power source, and this intake pipe negative pressure is feedback-controlled. Since it is kept constant, there is almost no change in the lift amount of the needle 47, and the pressure difference between the intake and exhaust gases is also approximately constant, making it possible to stabilize the EGR amount.

In addition to the illustrated example of the transducer 66, as a feedback mechanism for keeping the intake pipe negative pressure constant during operation of the intake air throttle device 6, a pressure sensor is disposed inside the intake pipe 2 and its signal is This can also be achieved by processing this in the controller 9 and causing the control valve 65 to control the duty ratio, and is not limited to the above embodiment. In addition to the EGR device 4 which processes and controls signals from the rotation sensor 5 and position switch 7 using the controller 9 as described above, various devices may be used.

As described above, the exhaust recirculation control device for a diesel engine according to the present invention includes an intake throttle device with a feedback mechanism that throttles intake air to a constant negative pressure by an intake throttle valve disposed in the intake pipe only during idling;
An EGR device detects the engine load and rotation speed using a rotation sensor and a fuel pump position switch when not idling, connects to a negative pressure source higher than the negative pressure, and operates an EGR valve.
Since the diaphragm chamber of the EGR valve is connected downstream of the intake throttle valve, the following effects are achieved.

First, since the diaphragm chamber and return pipe of the EGR valve are connected downstream of the intake throttle valve, it is possible to perform constant exhaust gas recirculation even during idle link, where there is almost no pressure difference between intake and exhaust. This has the effect of further suppressing the production of nitrogen oxides.

In addition, since the intake negative pressure generated during idling is smaller than the negative pressure from the negative pressure source, the amount of exhaust recirculation is prevented from becoming excessive, so idling operation, which tends to be unstable due to low engine speed, is It has a stabilizing effect.

Furthermore, when the intake throttle valve is activated, the intake negative pressure downstream of the valve is maintained at a constant value by the action of the feedback mechanism, so the amount of exhaust gas recirculation during idling is maintained at a constant level, making idling motion more stable. effective.

In addition, when the engine is not idling, the load and rotation of the engine are detected and the negative pressure from the negative pressure source is applied to the EGR.
Since it acts on the diaphragm chamber of the valve,
Since the opening amount of the EGR valve is increased compared to when the engine is idling, a larger amount of exhaust gas is recirculated, and nitrogen oxides, which are generated in larger quantities than when the engine is idling, can be effectively suppressed.

Further, since the intake air throttle device according to the present invention does not operate except during idling, the intake efficiency and engine output of the engine do not decrease in operating ranges other than idling.

Furthermore, since the downstream side of the intake throttle valve of the intake pipe is connected to the diaphragm chamber of the EGR valve, and the negative pressure downstream of the valve is simply introduced into the diaphragm chamber, vibrations caused by the intake throttle action of the intake throttle valve can be eliminated. The noise reduction effect is not impaired at all.

[Brief explanation of the drawing]

Figure 1 is a system diagram showing one embodiment of the present invention, Figure 2 is a system diagram showing an embodiment of the present invention.
The figure is a table showing the relationship between engine speed and fuel lever opening. 1; Engine, 2; Intake pipe, 3; Exhaust pipe, 4;
EGR device, 43; EGR valve, 5; rotation sensor, 6; intake throttle device, 61; intake throttle valve, 6
6; transducer, 7; position switch, 8; vacuum tank, 9; controller.

Claims (1)

[Claims] 1. An intake throttle device with a feedback mechanism that throttles the intake air to a constant negative pressure using an intake throttle valve installed in the intake pipe only when idling, and a rotation sensor and fuel pump position switch that reduce engine load and Exhaust recirculation control for a diesel engine, comprising an EGR device that detects rotational speed and connects to a negative pressure source higher than the negative pressure to operate an EGR valve, and connects a diaphragm chamber of the EGR valve downstream of the intake throttle valve. Device.