JPS6364627B2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention is applicable as a measure for purifying exhaust gas from automobiles, etc.
This invention relates to an intake throttle device for a diesel engine equipped with an EGR device, which allows the intake of a diesel engine equipped with an EGR device to be throttled.

[Conventional technology]

In recent years, in order to purify the exhaust gas of automobiles equipped with diesel engines, a pipe 5 having an EGR valve 4 is installed between the exhaust pipe 2 and intake pipe 3 of the engine 1, as shown in FIG. , an EGR rate control valve 6 is provided in the intake pipe 3, and by throttling the EGR rate control valve 6, a part of the exhaust gas E is returned to the intake air A, thereby reducing nitrogen oxide NOx in the exhaust gas E. The device is in use.

On the other hand, in order to reduce vibration and noise during idling, attempts have been made to adopt an intake throttle device, but this intake throttle only reduces intake negative pressure.
It is experimentally known that no effect occurs unless the temperature is 100 mmHg or higher. Here, the EGR shown in Figure 1
If the EGR rate control valve 6 is also operated to the throttle side in order to throttle the intake air during idling in an engine equipped with a device, the EGR rate will become excessive and the engine will stop at a negative intake pressure of only about 30 mmHg. This causes the problem of storage.

Therefore, various means for adjusting exhaust gas recirculation have been proposed. For example, an EGR that opens downstream of the intake throttle valve linked to the accelerator pedal.
There is an invention disclosed in Japanese Patent Publication No. 54-29651 in which an automatic valve is provided at the reflux port to automatically adjust the reflux amount.
This prior art automatically stops exhaust gas recirculation when the intake negative pressure is small, but it has the disadvantage that it cannot prevent the amount of recirculation from becoming excessive when the intake negative pressure is large. be.

As another prior art, a throttle valve provided in the intake pipe closes the open end of the exhaust gas recirculation pipe when the valve is fully opened.
There is an invention disclosed in Japanese Unexamined Patent Publication No. 1488/1988 in which the EGR control valve 6 and EGR control valve 6 are used as a common valve. However, with this prior art, it is not possible to finely adjust the amount of exhaust gas recirculation, and furthermore, it is not possible to prevent the amount of recirculation from becoming excessive when the intake air is throttled.

Another prior art that integrates an intake throttle valve and an exhaust gas recirculation amount control valve in the same manner as the prior art described above includes a throttle valve provided in the intake pipe with a valve that opens and closes the exhaust gas recirculation port that opens in the intake pipe. Japanese Patent Publication No. 54-17092 and Japanese Patent Application Laid-open No. 17092/1983, in which the opening degree of the recirculation port is adjusted by the opening degree of the throttle valve.
There is an invention in Publication No. -5445. However, although these prior art technologies can always keep the ratio of recirculation amount to intake air amount constant, they do not have a function to control intake negative pressure to a constant level, so increasing intake negative pressure may cause engine operation to become unstable. Since it becomes stable, there are drawbacks such as the fact that the noise reduction effect of intake throttle cannot be expected.

As another example, a throttle valve, an exhaust gas recirculation amount control valve, and an exhaust pipe back pressure control valve are linked to the accelerator pedal, and at the same time, the combustion amount is determined by measuring the intake air amount using a pressure receiving plate installed in the intake pipe or a hot wire. There is an invention disclosed in Japanese Unexamined Patent Application Publication No. 13730/1983 which is designed to adjust. However, this prior art has the drawback that, in addition to requiring a large-scale device, it cannot prevent the recirculation amount from becoming excessive when the intake air is throttled.

Therefore, there is a prior art technique that uses a power chamber driven by the intake velocity when passing through an intake throttle valve to adjust the amount of exhaust gas recirculation. For example, the invention disclosed in Japanese Patent Application Laid-Open No. 54-118920 includes an exhaust gas back pressure regulating valve that is operated by the differential pressure between the upstream intake negative pressure of the intake throttle valve and the exhaust pressure in the exhaust pipe, and The exhaust gas recirculation amount is controlled by adjusting the opening degree of the intake air amount control valve by the negative pressure generated in the bench lily pipe in which an interlocking intake throttle valve is provided in parallel. In addition, another prior art, JP-A-54-71233
In the invention disclosed in the publication, only the reflux amount is adjusted by the negative pressure generated in the bench lily tube.

However, these prior art techniques have drawbacks as a driving pressure source for the recirculation flow control valve because the output pressure and flow rate of the ventilator tube do not have a linear relationship, and the output pressure at idle is small. The drawback is that it is impossible to prevent the reflux amount from becoming excessive.

Therefore, the output was increased by controlling the vacuum tank and the power chamber operating at atmospheric pressure using the power chamber that guided the differential pressure generated between the two bench lily tubes to the air chambers on both sides of the diaphragm valve to the vacuum tank and the power chamber that led to atmospheric pressure. Tokukai Akira
There is an invention disclosed in Publication No. 53-86926. However, since this prior art uses a bench lily tube like the prior art, for the reasons mentioned above, sufficient operational stability during idling cannot be obtained, and furthermore, when the intake air is throttled, the recirculation amount becomes excessive. The disadvantage is that it cannot be prevented.

As another prior art, when idling
There is an invention disclosed in Japanese Unexamined Patent Publication No. 55-54660 that actively performs EGR to reduce vibration and noise.
However, this prior art simply throttles the intake air during idling, and does not have a function to control the intake negative pressure to a constant value, so increasing the EGR rate prevents the engine from becoming unstable due to fluctuations in the intake negative pressure. The problem is that it cannot be done.

As a prior art technique for stabilizing this intake negative pressure, a pressure regulating valve is installed to detect the intake pressure on the downstream side of the intake throttle valve and output a control pressure to the throttle valve to keep the negative pressure constant, and the exhaust pressure and cooling water temperature are low. In 1982, the output pressure was sometimes not transmitted to the throttle valve, and the intake pressure was kept constant during idling without throttling the intake air when starting the diesel engine.
There is an idea in Publication No. 49024. However, when EGR is used in conjunction with a diesel engine to which this prior art is applied, if the exhaust gas recirculates downstream of the intake throttle valve, the flow rate becomes excessive and the engine stops, and if the exhaust gas recirculates upstream of the throttle valve, the recirculation amount decreases. There may be a problem that sufficient EGR effect cannot be obtained due to insufficient amount.

[The problem that the idea aims to solve]

The present invention was made in view of the above problems, and an object of the present invention is to provide an intake throttle device for a diesel engine equipped with an EGR device, which can stabilize intake negative pressure during idling in the diesel engine equipped with an EGR device. It is said that

[Means for Solving the Problems] The configuration of the intake throttle device for a diesel engine with an EGR device according to the present invention to achieve the above object includes an intake throttle valve that releases a throttle whose operating pressure is atmospheric pressure, and A pressure regulating valve that detects the downstream intake pressure and outputs a driving pressure to keep the pressure constant, and a pneumatically operated
An EGR valve is provided, and the switching valve between atmospheric pressure and the driving pressure switches the operating pressure of the throttle valve to the driving pressure during idling and to atmospheric pressure during normal times, and uses the switching pressure to control the operation of the EGR valve during idling. It is characterized in that the reflux amount is sometimes reduced or made zero.

When implementing the present invention, a conventional EGR control valve can be installed as is, or the intake throttle valve can also be used as an EGR control valve.
In other words, during normal engine operation other than idling,
In the former case, the pressure regulating valve may be configured to control the EGR valve, and in the latter case, the pressure regulating valve may be configured to control the throttle valve and the EGR valve simultaneously.

The throttle amount of the EGR valve during idling may be determined depending on whether or not the exhaust gas components of the engine used require EGR during idling.

The switching valve is normally operated by a relay controlled by the following switch. For example, this switch is a switch that is turned on when the accelerator pedal is in the idling position, a switch that is turned on when the transmission is in neutral, a switch that is turned on when the coolant temperature is above a certain value, and a switch that is turned on when the coolant temperature is above a certain value. However, at high altitudes, there is an atmospheric pressure switch that is turned off.

〔Example〕

An embodiment in which the present invention is applied to an automobile equipped with a diesel engine will be described below with reference to FIGS. 2 to 4. Please refer to Figures 2 to 4.
The same drawer number is used in each of the embodiments up to the figure.

First, in the first embodiment of the present invention shown in FIG. 2, the intake pipe 3 is equipped with an intake throttle valve 8 that is opened and closed by a power chamber 7.
The spring S of this power chamber 7 is connected to the vacuum control valve 10 and the vacuum pump (VP) which constitute the pressure regulating valve from the port B of the solenoid valve 9 which constitutes the switching valve to the port A.
11, vacuum control valve 1
0's spring side S communicates with the intake pipe 3, and an atmosphere opening port a is provided on the valve side thereof.

Furthermore, in the illustrated state, port C of the solenoid valve 9
The spring side S of the EGR valve 4 communicates with the pipe line in which the air release port a and the port D communicate with each other, and the EGR valve 4 is connected to the exhaust pipe 2 and the intake pipe 3 by opening and closing the pipe. each conduit 5 of
a, 5b are communicated or blocked.

Next, 12 in Figure 2 is the diesel engine 1
The key switch 13 is a switch that is turned on when the engine 1 is in the idle position, the accelerator switch 14 is a transmission neutral switch that is turned on when the engine 1 is in the neutral position, 15 is a water temperature switch that is turned on when the engine 1 is warmed up, and 16 is a switch that is turned on when the engine 1 is in the idle position. , is an atmospheric pressure switch that turns on at a certain pressure or higher, and is a mechanism that cuts off the intake throttle device when the car is at high altitude. This is a relay that turns on.

Therefore, when the switches 12 to 16 shown in FIG. The intake throttle valve 8 is operated via the
The intake air can be throttled to increase the intake negative pressure to 100 mmHg or more when the engine 1 is idling.On the other hand, when the relay 1 is off, ports A and D of the solenoid valve 9 communicate with each other. Port B and port C (atmosphere release port a) are communicated, and the EGR valve 4 is opened by the pachyume pump (VP) 11.
Only the EGR function functions, and the function of the intake throttle valve 8 is cut off.

That is, when engine 1 is warm, such as when it is idling,
The EGR is cut off to throttle the intake air, and at other times the intake throttle is cut off and only the EGR function is performed.

Embodiment 2 of the present invention shown in FIG. 3 is an example in which the function of the EGR control valve 6 of the conventional example shown in FIG. is the same as in Fig. 2, but the solenoid valve 9 is connected from port B to port A or port C.
It is sufficient to switch to either (atmosphere release port a),
The illustrated state is when the relay 17 is on, and when the relay 17 is off, port B and port C (atmosphere release port a) are connected.

Also, the EGR valve 4' is different from the one shown in Fig. 2, in that the spring side S of the power chamber 7 and the spring side S of the EGR valve 4' communicate with each other, and the opening and closing of the EGR valve 4' causes the exhaust pipe 2 and the intake pipe to When the intake throttle valve 8 is operated, the opening of the EGR valve 4' is also closed to a certain value, and the EGR is used to connect or cut off the pipes 5a and 5b to the intake pipe 3. It has the function of restricting the flow rate of recirculated exhaust gas E to prevent the EGR rate from becoming excessive, and controlling the intake negative pressure to a constant value of 100 mmHg or more. Note that a small orifice 18 is provided inside the EGR valve 4'.

〔Effect of the invention〕

As explained above, the intake throttle device for a diesel engine with an EGR device of the present invention includes an intake throttle valve that releases the throttle when the operating pressure is atmospheric pressure, and an intake throttle valve that detects the downstream intake pressure and keeps the pressure constant. Equipped with a pressure regulating valve that outputs driving pressure and a pneumatically operated EGR valve,
The switching valve between atmospheric pressure and the driving pressure switches the operating pressure of the throttle valve to the driving pressure during idling and to atmospheric pressure during normal times, and uses the switching pressure to operate the EGR valve to throttle the recirculation amount when idling. Since this configuration is configured to set the value to zero, the following effects can be obtained.

In other words, a switching valve is provided that switches the operating pressure between atmospheric pressure and driving pressure using control during idling and control during other normal engine operation, and an intake throttle valve.
By switching the EGR valve and the EGR valve at the same time, it is possible to control the amount of EGR required during idling and to maintain a constant intake pipe internal pressure. It is possible to maintain stable operating conditions during idling.

[Brief explanation of drawings]

Figure 1 is a schematic system diagram of a diesel engine equipped with a conventional EGR device, and Figures 2 and 3 are EGR of the present invention.
Each embodiment of a schematic system diagram of an intake throttle device for a diesel engine with the device is shown, and FIG. 2 is the first embodiment, and FIG. 3 is the second embodiment. 1...engine, 2...exhaust pipe, 3...intake pipe,
4, 4'...EGR valve, 6...EGR rate control valve, 7...Power chamber for intake throttle valve, 8...
Intake throttle valve, 9... Solenoid valve (switching valve), 10
...vacuum control valve (pressure regulating valve),
17...Relay.

Claims (1)

[Claims] 1. An intake throttle valve that opens the throttle when the operating pressure is atmospheric pressure, a pressure regulating valve that detects the downstream intake pressure and outputs a driving pressure to keep the pressure constant, and a pneumatically operated EGR valve, The switching valve between atmospheric pressure and the driving pressure switches the operating pressure of the throttle valve to the driving pressure during idling and to atmospheric pressure during normal times, and uses the switching pressure to operate the EGR valve to throttle the recirculation amount when idling. This is an intake throttle device for a diesel engine equipped with an EGR device configured to reduce the temperature to zero.