JP2560704Y2 - Diesel engine exhaust purification system - Google Patents

Description

[Detailed description of the invention]

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improvement in an exhaust gas purification device for a diesel engine.

[0002]

2. Description of the Related Art In a diesel engine, a particulate filter is interposed in an exhaust passage to purify particulates (carbon fine particles) contained in exhaust gas, and a regeneration heat source supply means is provided upstream of the filter. It is known that a burner device is provided to operate the burner device at the time of regeneration of the filter to burn the particulates collected by the filter.

[0003] As a conventional exhaust purification apparatus for a diesel engine, Japanese Utility Model Laid-Open No. 3-19418 and Japanese Utility Model Laid-Open No. 2-11 are disclosed.
As disclosed in Japanese Patent No. 5908, a diffusion plate is provided on the upstream side of the filter to uniformly guide the combustion gas sent from the burner device to the filter, and the filter locally rises above its heat-resistant temperature. To prevent erosion and the like from occurring.

[0004]

However, in such a conventional exhaust gas purifying apparatus for a diesel engine, the filter is provided on the upstream side of the filter during normal operation in which particulates are collected by the filter. The diffusion plate increases the pressure loss. When the pressure loss is large, the fuel efficiency is deteriorated and the engine life is shortened.

The present invention has been made in view of the above problems, and has as its object to provide a structure suitable for an exhaust gas purifying apparatus having a diffusion plate on the upstream side of a filter.

[0006]

SUMMARY OF THE INVENTION According to the present invention, exhaust gas purification is provided in which a filter for a particulate trap is interposed in the exhaust passage of a diesel engine, and a burner device for burning the particulates collected in the filter is provided. In the apparatus, a diffusion plate having an opening is provided upstream of the filter, and a normally open temperature sensing valve for detecting the temperature of the combustion gas during regeneration and closing the opening is attached to the diffusion plate.

[0007]

In the normal operation, the temperature sensing valve opens the opening of the shielding plate to reduce the pressure loss applied to the flow of the exhaust gas.

During regeneration of the filter, the temperature sensing valve closes the opening of the shielding plate, guides the combustion gas sent from the burner device to a predetermined portion of the filter, makes the temperature distribution of the filter uniform, and causes the filter to locally reach its heat-resistant temperature. In addition to preventing the filter from rising above the melting point and reducing the regeneration time of the filter.

[0009]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described below with reference to the accompanying drawings.

As shown in FIG. 1, a filter 2 for collecting particulates is provided in an exhaust passage 1 of a diesel engine, and a burner device 3 for burning the particulates collected by the filter 2 is provided upstream of the filter. Can be

The exhaust passage 1 is provided with a bypass passage 4 for bypassing the filter 2 and exhausting the exhaust gas. Exhaust shutters 5 and 6 for opening and closing the inlet of the filter 2 and the inlet of the bypass passage 4 are provided.

The exhaust shutters 5, 6 close the bypass passage 4 and open the upstream side of the filter 2 during normal operation by the control unit 13 while the filter 2 is closed.
Open the bypass passage 4 and regenerate the filter 2
Is closed and the burner device 3 is operated. The control unit 13 detects whether the operation time of the engine has passed a predetermined time or whether the differential pressure across the filter 2 exceeds a predetermined value, determines the clogged state of the filter 2, and regenerates the filter 2. It is supposed to do.

The burner device 3 has a combustion chamber 7 which opens toward the center inlet of the filter 2 at a position slightly away from the flow of exhaust gas to the filter 2, and a nozzle which injects fuel from the fuel control valve 15 into the combustion chamber 7. 9, an air pump 10 that supplies air to the combustion chamber 7, and an ignition electrode 11 that ignites a mixture of fuel injected from the nozzle 9 and air from the air pump 10 in the combustion chamber 7. In the figure, reference numeral 8 denotes an inner cylinder in which a number of holes surrounding the tip of the injection nozzle 9 and the ignition electrode 11 are formed on the outer periphery.

The operation of the motor 12 of the air pump 10 is controlled by a control unit 13 via a motor rotation adjuster 14. The control unit 13 is driven together with the fuel control valve 15 of the injection nozzle 9 and the ignition electrode 11 at the time of regeneration of the filter 2 so as to control the residual air in the combustion gas of the burner device 3 to an appropriate amount required for particulate combustion. Has become.

With this configuration, during normal operation of the exhaust gas from the engine, the exhaust shutters 5 and 6 are connected to the bypass passage 4.
Is closed and the exhaust gas is guided to the filter 2, and the filter 2 collects particulates contained in the exhaust gas. When the control unit 13 determines that the trapped amount reaches the predetermined value, the control unit 13 opens the bypass passage 4 through the exhaust shutters 5 and 6 to open the filter 2.
The flow of exhaust gas to the filter 2 is cut off, the burner device 3 is operated, and the combustion gas is applied to the filter 2 to burn the particulates collected by the filter 2.

A disk-shaped diffusion plate 2 is provided upstream of the filter 2.
1 is provided. The diffusion plate 21 is configured to uniformly guide the combustion gas from the burner device 3 from the outer peripheral portion of the filter 2 to the filter 2.

One opening 22 is formed in the center of the diffusion plate 21 in a circular shape, and a temperature sensing valve 23 for opening and closing the opening 22 is provided.

The temperature sensing valve 23 includes a disc-shaped valve 24,
Hinge 25 made of shape memory alloy for opening and closing valve 24
Having.

As shown in FIG. 2, when the shape memory alloy hinge 25 is heated to 700 to 900 ° C. by the combustion gas from the burner device 3 during regeneration of the filter 2, the valve 2
4 is bonded to the diffusion plate 21 and the opening 22 is closed. On the other hand, during normal operation in which particulates are collected, the valve 24 is separated from the diffusion plate 21 when the temperature becomes 600 ° C. or less due to engine exhaust gas. And the opening 22 is opened.

Next, the operation will be described.

During normal operation in which particulates are collected by the filter 2, the temperature sensing valve 23 opens the opening 22 of the shielding plate 21 to reduce the pressure loss applied to the flow of exhaust gas.

During regeneration of the filter 2, the temperature sensing valve 23
Closes the opening 22 of the shielding plate 21, guides the combustion gas sent from the burner device 3 to a predetermined portion of the filter 2 through the diffusion plate 21, and makes the temperature distribution of the filter 2 uniform. It is possible to avoid a rise in the temperature beyond the heat-resistant temperature and melting, thereby shortening the regeneration time of the filter 2.

Next, in another embodiment shown in FIG. 3, seven openings 32 are formed in one diffusion plate 31, and each of the openings 32 is formed.
Is provided with a temperature sensing valve 33 that opens and closes.

Each temperature sensing valve 33 includes a disc-shaped valve 34.
And a hinge 35 made of a shape memory alloy for opening and closing the valve 34.

In this case, the sum of the opening areas of the openings 32 can be increased to further reduce the pressure loss applied to the flow of the exhaust gas during normal operation.

[0026]

As described above, according to the present invention, a filter for a particulate trap is interposed in the exhaust passage of a diesel engine, and a burner device for burning the particulates collected by the filter is provided. In the purification device, a diffusion plate having an opening is provided upstream of the filter, and a normally open temperature sensing valve for detecting the temperature of the combustion gas during regeneration and closing the opening is attached to the diffusion plate. Thus, it is possible to prevent the filter from being damaged during regeneration, prevent an increase in pressure loss during normal operation, and reduce the regeneration time of the filter.

[Brief description of the drawings]

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

FIG. 2 is a principle diagram showing the operation of the temperature sensing valve.

FIG. 3 is a front view of a diffusion plate and a temperature sensing valve showing another embodiment.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Exhaust passage 2 Filter 3 Burner device 21 Diffusion plate 22 Opening 23 Temperature sensing valve

Claims (1)

(57) [Scope of request for utility model registration] 1. An exhaust gas purifying apparatus in which a filter for a particulate trap is interposed in the exhaust passage of a diesel engine and a burner device is provided for burning the particulates collected by the filter. An exhaust gas purification device for a diesel engine, wherein a diffusion plate having an opening is provided on the first diffusion plate, and a normally open temperature sensing valve for detecting the temperature of combustion gas during regeneration and closing the opening is attached to the diffusion plate.