JPH03294613A - Exhaust emission control device for engine - Google Patents

Abstract

PURPOSE:To effectively reduce white smoke emitted in idling territory by providing a control means to actuate a main and a subsidiary opening/closing valves at detecting operation of an engine in idling territory. CONSTITUTION:The upper stream part and the lower stream part of a main opening/closing valve 4 provided on the exhaust passage 3 of an engine 1 are connected together through a bypass passage 5, and a trap 6 for collecting white smoke is provided on the bypass passage 5. A rotation sensor 9 to detect rotating speed of the engine 1 and a temperature sensor 10 to detect temperature of the engine are connected to a controller 8. When the engine 1 is operated in the idling territory, the main valve 4 is opened and subsidiary opening/closing valve is closed by a command from the controller 8. In this way, while restraining clogging of the trap due to particulate component in exhaust gas, white smoke emitted in the idling territory can be effectively reduced.

Description

[Detailed Description of the Invention] <Industrial Application Field> The present invention relates to an engine exhaust treatment device, and more specifically,
The present invention relates to a device that can reduce white smoke emitted during warm-up operations.

<Prior Art> For example, in a diesel engine, white smoke may be emitted immediately after the engine is started. This kind of white smoke is
This is often seen during engine warm-up, and as unburned fuel is discharged as is, improvements have been desired from the perspective of air pollution and environmental purification.

In this way, in order to reduce the white smoke emitted during engine warm-up, conventional methods have been used, such as Japanese Patent Application Laid-Open No. 61-6190.
As seen in Publication No. 7, etc., it was considered effective to provide an exhaust purification catalyst in a part of the exhaust passage.

However, when an exhaust purification catalyst is installed in the exhaust passage, the desired purpose can be achieved in the region where the temperature of the exhaust gas is high enough and the catalyst is activated, but when the catalyst is There was a problem in that it was not particularly effective against white smoke emitted when the temperature was not high enough.

<Problem to be solved by the invention> The present invention has been made in view of the above circumstances.
The object of the present invention is to provide an exhaust treatment device that can effectively collect white smoke emitted from an idle area or the like.

<Means for Solving the Problems> In order to achieve the above object, the present invention connects the upstream and downstream sides of the main on-off valve provided in the exhaust passage of the engine via a bypass passage, and uses the bypass passage to trap white smoke. A trap is set up for collection. Further, an auxiliary on-off valve is provided in the bypass passage upstream of the trap, and a detection means for detecting the operating state of the engine is provided, and based on the output of this detection means, it is detected that the engine is being operated in an idle region. The main feature is that a control means is provided that sometimes causes the main on-off valve to close and the auxiliary on-off valve to open.

<Operation> In the engine exhaust treatment device configured as described above, when the engine is operated in a normal range other than the idle range, the main on-off valve is opened and the auxiliary on-off valve is opened by a command from the control means. Closed. Therefore, in this state, the exhaust gas from the engine does not pass through the bypass passage, so that clogging of the white smoke trap provided in the bypass passage is avoided.

On the other hand, when the engine is operated in an idle region, the main on-off valve is closed and the auxiliary on-off valve is opened based on a command from the control means. Then, the exhaust gas from the engine is discharged through the bypass passage, and the white smoke is collected by a trap provided in the bypass passage, so that no white smoke is released into the atmosphere.

Also, if the main on-off valve is closed and the auxiliary on-off valve is opened only in the idle range where the engine temperature is lower than a predetermined value,
Exhaust air is not supplied to the bypass passage without the possibility of white smoke being discharged. Therefore, even if particulate components such as carbon are contained in the exhaust gas, deterioration (clogging, etc.) of the trap can be suppressed. In addition, by setting the passage resistance of the bypass passage equipped with a white smoke collection trap to be greater than the passage resistance of the exhaust passage, the back pressure in the idle region is increased even when the auxiliary on-off valve is fully open, and combustion is maintained. This can improve warm-up and prevent the generation of white smoke. Furthermore,
If the auxiliary on-off valve is closed when the exhaust brake is activated, the main on-off valve can also be used as the exhaust brake valve to form an exhaust brake system.

<Example> Examples of the present invention will be described in detail below based on the drawings.

FIG. 1 is a schematic diagram showing an embodiment of an engine exhaust treatment device according to the present invention, in which a main opening/closing valve 4 is provided in an exhaust passage 3 leading from an exhaust manifold 2 of an engine 1 to a muffler (not shown). Further, a bypass passage 5 is provided to connect the upstream and downstream sides of the main on-off valve 4, and a trap 6 for collecting white smoke is provided in the bypass passage 5.

The trap 6 separates and collects unburned fuel components contained in the exhaust gas, and is constructed by filling the bypass passage 5 with, for example, SUS wire mesh or ceramic fiber. An auxiliary on-off valve 7 is provided in the bypass passage 5 upstream of the trap 6, and the main on-off valve 4 and the auxiliary on-off valve 7 are connected to an output terminal of a controller 8.

Further, a rotation sensor 9 detects the rotation speed of the engine 1, and a temperature sensor 1 detects the temperature of the engine 1 (cooling water).
0 etc. to the input terminal of the controller 8, the engine 1 is operated in a region (idle region) where the rotational speed of the engine 1 is lower than, for example, 750 rpm, and the temperature of the engine 1 is set to a predetermined value (for example, 50° C.). Only when it is determined that the temperature is lower than that, the main on-off valve 4 is closed and the auxiliary on-off valve 7 is opened in response to a command (signal) from the controller 8.

In the engine exhaust treatment device configured as described above, when the engine 1 is operated, the rotational speed and temperature (cooling water temperature) at that time are supplied to the controller 8 from the rotation sensor 9 and the temperature sensor IO.

When the engine speed supplied in this way is higher than a predetermined value and when the temperature is higher than a predetermined value, the main opening/closing valve 4 is held in the open state based on a command from the controller 8, and the secondary opening/closing valve is held open. Valve 7 is maintained closed.

Therefore, since the exhaust gas from the engine 1 is supplied to the muffler (not shown) without passing through the bypass passage 5, even if particulate components such as carbon are contained in the exhaust gas,
Since this particulate component is not collected in the trap 6, clogging of the trap 6 is avoided.

On the other hand, when the rotational speed of the engine 1 is lower than a predetermined value and the temperature is lower than a predetermined value, the main on-off valve 4 is closed and the auxiliary on-off valve 7 is opened according to a command from the controller 8. Then, the exhaust from the engine 1 flows into the bypass passage 5.
In order to be supplied to a muffler (not shown) via the trap 6, unburned fuel components contained in the exhaust gas are collected and separated by the trap 6, and only the exhaust gas that does not contain unburned fuel components is supplied to the muffler. Therefore, the exhaust gas released into the atmosphere does not contain unburned fuel components, and the emission of white smoke is prevented.

That is, the rotation speed of the engine 1 is lower than the predetermined value, and
Only when the temperature of the engine 1 is lower than a predetermined value (when there is a possibility of white smoke being emitted), the exhaust gas is guided to the muffler via the bypass passage 5 to prevent white smoke from being emitted. Exhaust gas is not supplied to the trap 6 during operation in a normal rotation range where there is no possibility of exhaustion and during operation in a warm-up state. For this reason, even if the exhaust gas contains fine particles of carbon, it is possible to suppress clogging of the trap 6 due to these fine particles.

FIG. 2 shows another embodiment of the exhaust treatment device according to the present invention. In this embodiment, by making the passage resistance of the bypass passage 5 larger than the passage resistance of the exhaust passage 3,
The back pressure when the main on-off valve 4 is closed and the auxiliary on-off valve 7 is opened can be made higher than the back pressure when the main on-off valve 4 is opened. For this reason, in this embodiment, the back pressure in the idle region can be actively increased, and the combustion temperature can be raised by increasing the residual gas, which accelerates warm-up and generates white smoke. is suppressed.

In addition, in the embodiment shown in FIG.
A valve 13 is interposed between the vacuum tank 12 and a diaphragm 14 provided as an actuator for the auxiliary on-off valve 7, and a valve 15 is interposed between the vacuum tank 12 and the valve 13.15 and the power source 16 are not shown. A limit switch 17 that is closed when the fuel lever provided on the fuel injection pump is in the idle position, a white smoke switch 18 that is manually opened and closed, and a white smoke switch 18 that is closed when the rotation speed of the engine 1 is lower than a predetermined value. When the white smoke switch 18 is closed, the fuel lever is in the idle position, and the rotational speed of the engine 1 is lower than a predetermined value. The main on-off valve 4 is closed and the auxiliary on-off valve 7 is opened only during this period.

Further, an exhaust brake switch 20 which is manually controlled to open and close is connected in parallel to a series circuit of a white smoke switch 18 and a control switch 19, which constitute a part of the circuit for energizing the valve 13 on the main opening/closing valve 4 side. . Therefore, white smoke switch 1
Even if at least one of the control switch 8 or the control switch 19 is opened and the sub-opening/closing valve 7 is held closed, if the exhaust brake switch 20 is closed, the main opening/closing of the paddy will continue if the fuel lever is in the idle position. Valve 4 is operated to close. Therefore, in this embodiment, the main opening/closing valve 4 can be opened and closed in the same manner as a conventional exhaust brake valve. Even if the white smoke switch 18 is closed, if the rotation speed of the engine 1 is higher than a predetermined value, the control switch 19 is held open to prevent the auxiliary on-off valve 7 from opening, and the rotation of the engine 1 is maintained. When the number becomes lower than a predetermined value and the control switch 19 is closed, the auxiliary on-off valve 7 is opened to prevent the back pressure from increasing more than necessary. White smoke emitted in the idle area can be reduced without any damage.

That is, in the embodiment shown in FIG. 2, the main on-off valve 4 can be closed when white smoke is discharged and the exhaust brake is activated, and the auxiliary on-off valve 7 can be closed when the exhaust brake is activated. Therefore, a decrease in exhaust braking force due to the provision of the bypass passage 5 is prevented.

<Effects of the Invention> As is clear from the above description, according to the present invention, exhaust gas is supplied to the trap only when the engine is operating in the idle range, and is not led to the trap in other operating ranges. Therefore, it is possible to effectively reduce the amount of white smoke emitted in the idle region where the temperature of the exhaust gas is low while suppressing clogging of the trap due to particulate components in the exhaust gas.

[Brief explanation of drawings]

FIG. 1 is a schematic block diagram showing one embodiment of the present invention, and FIG. 2 is a schematic block diagram of main parts showing another embodiment of the present invention.

Claims (3)

[Claims] (1) A main on-off valve provided in the exhaust passage of the engine, a bypass passage connecting the upstream and downstream of the main on-off passage, a trap for collecting white smoke provided in the bypass passage, and a trap provided upstream of the trap. A secondary on-off valve provided in the bypass passage, a detection means for detecting the operating state of the engine, and the main on-off valve is closed when it is detected that the engine is being operated in an idle region based on the output of the detection means. An exhaust gas treatment device for an engine, comprising control means for operating a valve and opening the sub-opening/closing valve. (2) The engine according to claim 1, wherein the control means operates to close the main on-off valve and open the auxiliary on-off valve when the engine is operating in an idling region where the temperature of the engine is lower than a predetermined value. Exhaust treatment equipment. (3) The engine exhaust treatment device according to claim 1 or 2, wherein the control means closes the auxiliary on-off valve when the exhaust brake is activated when the engine speed is higher than a predetermined value.