CN100419228C - A method and device for reducing particulate matter emissions from diesel engines - Google Patents

Abstract

The present invention is a method and device for reducing particulate matter emissions from diesel engines. The method is that the diesel engine exhaust gas containing particulate matter is axially introduced into the inner cavity of a cylindrical filter body composed of a plurality of filter units, and then radially passes through the cylindrical filter body. The particulate matter in the exhaust gas is filtered by the filter body, and then discharged from the exhaust gas outlet pipe; at least one filter unit of the rotatable cylindrical filter body is always in the regeneration chamber, and the other filter units are in the filtering working state; in the microwave Under the action of energy, the exhaust particulate matter deposited on the filter unit in the regeneration chamber is spontaneously ignited and removed to regenerate the filter unit; the cylindrical filter body in the filtering process is properly rotated to synchronize the filter units in turn regeneration. The device of the invention can be continuously regenerated without secondary pollution, and has the characteristics of small filtering resistance of the system, low power of the regenerative energy source, convenient installation and maintenance, compact radial structure, and convenient vehicle layout design.

Description

A method and device for reducing particulate matter emissions from diesel engines

technical field

The invention relates to a method and a device for post-treatment of diesel engine tail gas, which can reduce the discharge of particulate matter in the diesel engine tail gas.

technical background

Particulate matter (PM), which is mainly composed of soot and other substances, exists in the exhaust of diesel engines. These particulate matter are very harmful, so PM emission has become a bottleneck problem restricting the further development of diesel engines.

At present, the relatively mature method of controlling PM emissions from diesel engines is mainly internal purification, that is, through measures such as improving the structural design of the engine, improving fuel quality, optimizing fuel supply characteristics, and rationally organizing combustion to reduce its generation. However, the method of purifying PM inside the engine is approaching its limit, and the industry generally believes that only by combining exhaust post-treatment can the PM emission of diesel engines meet the more stringent regulatory requirements in the future.

In the prior art, there are many post-treatment methods for diesel engine particulate matter exhaust, among which the use of filtration to reduce particulate matter is considered to be one of the most promising methods, but the regeneration of filter facilities in this regeneration method will be a Difficulties to overcome.

The main part of the diesel engine exhaust filtration facility is the particulate filter (or particle trap). It is more common to pass the diesel engine exhaust axially through the filter body; however, as the particles deposited on the filter body increase, the filtration resistance increases. After that, the filter body needs to be regenerated to remove the soot particles deposited on the filter body, so that it can be used again.

When the filter body is regenerated, the current common practice is to discharge the exhaust gas directly into the atmosphere through the bypass valve, or use more than two sets of filter devices to undertake the filtering task and regeneration in turn, so the whole structure is very complicated and the reliability is not high.

For an engine with a larger displacement, in order not to make the filter resistance too large, it is necessary to make the cross-sectional area of the filter body larger, that is, the radial dimension is larger; in this way, the filter body is not easy to be heated evenly during regeneration, and it is easy to Crack and damage the filter body. Moreover, due to the large size of the filter body, the power consumed by the energy source during active regeneration is large, which will also pose a challenge to the vehicle battery and is not conducive to the layout design of the vehicle.

Contents of the invention

The object of the present invention is to propose a method and device for reducing particulate matter emissions from diesel engines, which can be continuously regenerated and have no secondary pollution, and the resistance of system filtration is small. , The power of the regenerative energy source is small, the installation is convenient, the maintenance is convenient, the radial structure is compact, and the layout design of the whole vehicle is convenient.

One of the technical proposals of the present invention is that the method for reducing particulate matter emissions from diesel engines is to introduce the diesel engine exhaust containing particulate matter axially into the inner cavity of a cylindrical filter body composed of a plurality of filter units, and then radially pass through The cylindrical filter body filters the particulate matter in the exhaust gas, and then it is discharged from the exhaust gas outlet pipe; at least one filter unit of the rotatable cylindrical filter body is always in the regeneration chamber, and the other filter units are in the filtering work state; under the action of microwave energy, the particulate matter deposited on the filter unit in the regeneration chamber is spontaneously ignited and removed, so that the filter unit is regenerated; the cylindrical filter body is properly rotated so that each filter unit is successively regenerated .

Further, the velocity of the airflow flowing through the filter unit in the regeneration chamber is controlled to better realize the regeneration.

The second technical solution of the present invention is that the structure of the device for reducing particulate matter emissions from diesel engines is that it has an exhaust gas inlet pipe with one end as an air intake end and the other end as a closed end, and an air flow channel is opened on the pipe wall. An exhaust gas collection cover is provided on the outside, and a cylindrical support with an airflow channel on the cylinder wall is provided between the exhaust gas introduction pipe and the exhaust gas collection cover; at least four identical filter units are installed on the cylindrical support to form a A cylindrical filter body, a partition plate is provided between every two adjacent filter units, there is an annular gap between the cylindrical support and the exhaust gas introduction pipe, the cylindrical filter body and the exhaust gas collection cover There is also an annular gap between them; the end of the exhaust gas collection cover close to the inlet end is provided with a sealing end cover, and the inlet port is located outside the sealing end cover; the end cover at the other end of the exhaust gas collection cover is sealed with the exhaust gas collection cover Connected and rotatable relative to it, the inner side of the end cover at the other end of the exhaust gas collection cover is fixedly connected with the cylindrical bracket and its outer side is connected to the motor synchronously through the connecting shaft; one side is provided with the exhaust gas outlet pipe The other side of the collection cover is equipped with a microwave generator, and a microwave confinement cover corresponding to at least one filter unit is provided between its microwave launch port and the cylindrical filter body. A regenerative flow rate control plate is arranged under the inner surface of the bracket and is installed on the exhaust gas introduction pipe through a connecting rod.

The present invention is further described below.

As shown in Figure 1 and Figure 2, during actual use, the device of the present invention is serially connected to the exhaust system of the diesel engine through the two flanges at the inlet and outlet positions, and the stepping motor and microwave generation source are controlled by the electronic control unit on the vehicle. (ECU) control; after the diesel engine exhaust gas containing PM enters the exhaust gas introduction pipe 2, it flows from the airflow passage 20 on the circumference pipe wall of the exhaust gas introduction pipe 2, the airflow passage 7 on the cylindrical support 6, and the cylindrical filter body 27 successively. Radial outflow; after the exhaust gas comes out from the cylindrical filter body 27, it becomes clean exhaust gas containing less PM, and under the constraint of the outermost exhaust gas collection cover 3, the exhaust gas enters the exhaust gas outlet pipe 21 and is discharged by it; The PM substances in the exhaust gas are deposited on the cylindrical filter body 27 . As the deposition of PM on the filter body increases, the resistance of the filter body increases to a certain extent, and the system starts to regenerate. During regeneration, the microwave generator 5 emits energy, and under the action of the microwave confinement cover 4, all the microwave energy is concentrated on the carbon-containing particulate matter deposited on the regenerated filter unit 19; since the steel wall can effectively shield microwaves, and The filter unit 19 that adopts foamed ceramic material is almost transparent to microwave, so the nearly airtight regeneration zone formed by the dividing plate 26 on both sides of the microwave confinement cover 4, the regeneration flow control plate 9, the cylindrical support 6 and the filter unit 19 The cavity 28 is repeatedly reflected, and finally almost all the energy is absorbed by the particulate matter deposited on the filter unit, so that the particulate matter is heated, heated, and burnt in situ, completing the regeneration of a filter unit.

When the filter unit is regenerated, the air flow passing through the filter body will exchange heat and mass with the filter body frame itself and the particulate matter deposited on the filter body, which will affect the regeneration speed and efficiency of the filter body. The flow control plate 9 controls the airflow velocity flowing through the filter body within an appropriate range; see Figure 2, the tighter the regenerative flow control plate 9 and the cylindrical bracket 6 fit together, the smaller the gap between the two , the smaller the velocity of the airflow flowing through the filter unit in the regeneration chamber during regeneration, on the contrary, the greater the velocity of the airflow flowing through the filter unit during regeneration.

Between said every two filter units 19, there is a dividing plate 26 fixed on the cylindrical support 6, and its effect is: in addition to forming an airtight regeneration cavity 28 with components such as the microwave confinement cover 4 to concentrate the microwave energy Outside, also strengthened the intensity of cylindrical filter body 27, cylindrical support 6.

Once a certain filter unit 19 is regenerated, the stepper motor 15 will drive the cylindrical support 6 through the bracket assembly 14, the transmission shaft 13, the spokes 12, and the end cap 11, and then drive the entire cylindrical filter body 27 to rotate an angle, The angle is equal to 360° divided by the number of filter units 19, so that the next adjacent filter unit is in the regeneration chamber for regeneration; the filter unit that has been regenerated enters the filtering state. By analogy, continuous regeneration of the cylindrical filter body 27 can be realized.

As can be seen from the above, the present invention is a method and device thereof for reducing diesel engine particulate matter emissions, and its beneficial effects include:

1. Since the present invention is a radial filter, the filter resistance can be reduced by increasing the axial length of the filter body, while the general axial filter body can only reduce the filter resistance by increasing the cross-sectional area, that is, increasing the diameter. For automobile design, the radial dimension of the exhaust aftertreatment device is strictly required and is not sensitive to the axial dimension requirement. The present invention can design the radial dimension of the entire device to be smaller by appropriately increasing the length, which is very beneficial to the entire vehicle layout;

2. In the present invention, the ratio of the filter cross-sectional area of the filter body to its volume is large, that is, less filter materials are required for a certain filter area, which saves the cost of valuable filter materials and reduces the system cost;

3. Since the regeneration of the filter body in this device is carried out step by step with a single filter block as the object, rather than at the same time with the entire filter body as the object, the power of the microwave source can be relatively small, and the requirements for the vehicle power supply are relatively low. The vehicle-mounted power supply used is generally available directly, without the need to install a special vehicle-mounted power supply;

4. When the device is regenerated and heated, due to the small volume of the filter unit, the stress generated due to uneven heating is relatively small, so the possibility of cracking and scrapping the filter body is greatly reduced, and the life of the entire filter body is greatly extended;

5. During operation, even if a certain filter unit is damaged, only the damaged filter unit can be replaced, and there is no need to replace the filter body as a whole, so it is convenient for maintenance and saves the use cost;

6. This device can easily realize the continuous regeneration of the filter body, and the regeneration process does not affect other parts of the discharge system, which is convenient for automatic control;

7. The structure is compact and simple, and there is no need like other filtration systems: either set up a regeneration bypass pipe controlled by a solenoid valve, so that regeneration and filtration cannot be performed simultaneously; or set up more than two sets of filtration systems, and regeneration and filtration are performed in turn. Therefore, the present invention reduces the probability of failure;

8. It is easy to realize the matching of microwave and regenerative unit, and there is no need to change the waveguide shape of microwave like other forms of particulate filter devices, so the energy utilization efficiency and regeneration efficiency are high, etc.

Description of drawings

Fig. 1 is a schematic longitudinal section of an embodiment of the device of the present invention;

Fig. 2 is a sectional view along line A-A in Fig. 1 .

In the above attached drawings:

1-flange, 2-exhaust gas inlet pipe, 3-exhaust gas collection cover,

4-Microwave Confinement Cover, 5-Microwave Generator, 6-Cylindrical Bracket,

7-Air flow channel 8-Connecting rod, 9-Regeneration flow rate control board,

10-Fastener, 11-End Cap, 12-Spoke,

13-Heat breaker slot, 14-Bracket assembly, 15-Stepper motor,

16-Arrow indicating the flow direction of diesel engine exhaust containing PM, 17-Sealing end cover,

18-Seal, 19-Filter unit, 20-Breath,

21-Exhaust gas outlet pipe, 22-Arrow indicating the direction of diesel engine exhaust after PM filtering,

23-flange, 24-side seal, 25-fastener,

26-partition plate, 27-cylindrical filter body, 28-regeneration cavity,

29, 30-ring gap, 31-drive shaft.

Detailed ways:

Referring to Fig. 1 and Fig. 2, the structure of a kind of device that realizes the inventive method is that it has one end to be the inlet end and the other end is the tail gas introduction pipe 2 of closed end, and the pipe wall has this tail gas introduction pipe 2 of air passage 20 Exhaust gas collection cover 3 is arranged on the outside, and a cylindrical support 6 with an airflow passage 7 on the cylinder wall is provided between the exhaust gas introduction pipe 2 and the exhaust gas collection cover 3; at least four identical filter units 19 are installed on the circular A cylindrical filter body 27 is formed on the cylindrical support 6, and a partition plate 26 is arranged between every two adjacent filter units 19, and there is an annular gap between the cylindrical support 6 and the exhaust gas introduction pipe 2. 29. There is an annular gap 30 between the cylindrical filter body 27 and the exhaust gas collection cover 3; the end of the exhaust gas collection cover 3 near the inlet end is provided with a sealing end cover 17, and the inlet port is located on the sealing end cover 17 External: the end cover 11 at the other end of the exhaust gas collection cover 3 is sealed and connected with the exhaust gas collection cover 3 and can rotate relatively, the inner side of the end cover 11 at the other end of the exhaust gas collection cover 3 is fixed with the cylindrical support 6 Connected and its outer side is synchronously connected to the rotating shaft of the motor 15; one side is provided with a microwave generator 5 on the other side of the exhaust gas collection cover 3 of the exhaust gas outlet pipe 21, and a microwave generator 5 is installed between the microwave emission port and the cylindrical filter body 27. A microwave confinement cover 4 corresponding to at least one filter unit 19 is provided between them, and a regenerative flow rate control plate 9 is arranged below the inner surface of the cylindrical support 6 corresponding to the microwave confinement cover 4, and it is installed on a connecting rod 8. The tail gas is introduced into the pipe 2.

The inlet port of the exhaust gas introduction pipe 2 is provided with a connecting flange 1 , and the outlet end of the exhaust gas outlet pipe 21 is provided with a connecting flange 23 .

One end of the partition plate 26 arranged between every two adjacent filter units 19 is fixedly connected with the cylindrical support (see FIG. 2 ).

The gap between the regeneration flow rate control plate 9 and the cylindrical support 6 is adjustable (see FIG. 2 ).

As shown in Figure 1, in order to reduce the heat conduction in the exhaust gas, the end cover 11 at the other end of the exhaust gas collection cover 3 is connected with one end of the drive shaft 31 with the spoke 12, and the other end is connected to the rotating shaft of the motor 15 synchronously. Have radial thermal insulation groove 13 on this power transmission shaft 31, so that the temperature of the bearing on the support, stepper motor 15 can not be too high. The stepper motor 15 can be installed on the tail gas outlet pipe 21 with a bracket.

As shown in FIG. 1 , each filter unit 19 can be made into an arc-shaped structure corresponding to the surface of the cylindrical support 6 . Each filter unit 19 can be made of ceramic foam material or related materials.

Claims (6)

1. the device of a reducing diesel engine microparticle matter exhaust, it is characterized in that, it has an end is inlet end and the other end is the tail gas ingress pipe (2) of closed end, this tail gas ingress pipe (2) outside that tube wall has air-flow path (20) is provided with exhaust collection cover (3), is provided with the cylinder-shaped bracket (6) that barrel has vent (7) between described tail gas ingress pipe (2) and the exhaust collection cover (3); At least four identical filter elements (19) are installed in described cylinder-shaped bracket (6) and go up and composition cylindrical shape filter (27), be equipped with demarcation strip (26) between per two adjacent filter elements (19), between described cylinder-shaped bracket (6) and the tail gas ingress pipe (2) annular space (29) is arranged, between described cylindrical shape filter (27) and the exhaust collection cover (3) annular space (30) is arranged; One end of the close described inlet end of exhaust collection cover (3) is provided with end cover (17) and the inlet end port is positioned at sealing end cap (17) outside; The end cap (11) of described exhaust collection cover (3) the other end is tightly connected and can rotates to it with this exhaust collection cover (3), and fixedly connected and its outside connects with the rotating shaft of stepping motor (15) with described cylinder-shaped bracket (6) in the inboard of the end cap (11) of described exhaust collection cover (3) opposite side; The opposite side that one side is provided with the described exhaust collection cover (3) of tail gas delivery line (21) is equipped with microwave oscillator (5), being provided with between its microwave emission port and the cylindrical shape filter (27) can be corresponding to the microwave containment shroud (4) of at least one filter element (19), is provided with regeneration velocity control panel (9) in cylinder-shaped bracket (6) the internal surface below corresponding to described microwave containment shroud (4) and it is installed on the described tail gas ingress pipe (2) with connecting rod (8).

2. according to the device of the described reducing diesel engine microparticle matter exhaust of claim 1, it is characterized in that the inlet end port of described tail gas ingress pipe (2) is provided with flange (1), the outlet end of described tail gas delivery line (21) is provided with flange (23).

3. according to the device of the described reducing diesel engine microparticle matter exhaust of claim 1, it is characterized in that a described end that is located at the dividing plate (26) between per two adjacent filter elements (19) is fixedly connected with described cylinder-shaped bracket.

4. according to the device of the described reducing diesel engine microparticle matter exhaust of claim 1, it is characterized in that the gap between described regeneration velocity control panel (9) and the cylinder-shaped bracket (6) is adjustable.

5. according to the device of the described reducing diesel engine microparticle matter exhaust of claim 1, it is characterized in that, the end cap (11) of described exhaust collection cover (3) opposite side connects with an end of the same transmission shaft of spoke (12) (31), has radially heat dam (13) on the other end this transmission shaft (31) with the rotating shaft connection of stepping motor (15).

6. according to the device of the described reducing diesel engine microparticle matter exhaust of claim 1, it is characterized in that described each filter element (19) is and the corresponding arc-shaped structure in cylinder-shaped bracket (6) surface.

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