JPS6319534Y2 - - Google Patents

Description

[Detailed description of the invention] The present invention relates to an exhaust gas purification device for a diesel engine, and more specifically, it uses a physical method to remove carbon particles and similar particulate matter (hereinafter referred to as exhaust particulates or particulate matter) contained in exhaust gas. The present invention relates to a structure of a particulate trap suitable for collecting on a suitable trap material such as a filter element, periodically incinerating the collected exhaust particulates, and regenerating the trap material.

Most of these types of exhaust particles are flammable, such as carbon particles, and diesel particulate trucks collect these flammable particles and incinerate them to regenerate trap material. There are various known types. An electric heater is generally used as a means for burning the collected particulate and regenerating the trap. That is, an electric heater is attached to the front end surface of the trap material, and the heater burns the exhaust particulates adhering to the surface of the trap material, and uses this as a heat source to cause the downstream particulates to self-combust. As a heater, an electric heating source such as a normal nichrome wire is generally wound in a zigzag or concentric pattern. The reason why the heater wire has such a special shape is to allow exhaust gas to pass through, while also heating the entire front end of the trap material to uniformly ignite and burn the exhaust particulates collected by the trap material. This is so that you can get it.

However, in conventional exhaust gas purification devices (particulate traps), the heater is attached to the front end surface of the trap material, that is, the front surface of the trap material, in order to maximize the ignition of exhaust particulates by the heater. The arrangement is such that it comes into contact with exhaust particulates. In other words, the arrangement is such that emphasis is placed on the ignitability of the heater. However, with this arrangement, the entire trap is subject to engine vibrations (the trap container is mounted directly on the exhaust pipe connected to the engine, so it is also subject to engine vibrations), and the heater wire and the front of the trap material are subject to intense rubbing. As a result, both wear out. As a result, the heater wire may eventually break or a large gap may be created between the heater wire and the trap material. A situation had arisen in which the fire could not be ignited.

In view of this, the present invention solves the above-mentioned problems of the prior art by attaching the heater to the trap container with a slight distance from the front end of the trap material, thereby increasing the reliability and durability of the exhaust gas purification device. The aim is to improve the

In addition, in this invention, the power setting of the heater is set higher in advance than when the heater and the trap material are in contact, taking into account the gap between the heater and the trap material, thereby reducing the adverse effect on the ignitability of the heater. Of course, it is important to ensure that this does not occur.

The following description will be made with reference to the accompanying drawings.

1 and 2 show the overall structure of a particulate trap according to the present invention, in which a trap material (filter) 3 and a heater 5 are disposed within a trap container 1. As the trap material 3, known foamed ceramic or similar materials can be used. That is, the trap material 3 has a three-dimensional mesh structure, through which the exhaust gas can flow, and exhaust particulates contained in the exhaust gas can be collected between the meshes.

A trap container 1 is placed in an exhaust pipe 2 of a diesel engine. It is assumed that exhaust gas flows in the direction of the arrow in the figure.

The heater 5 is composed of, for example, six heater wires 8A to 8F arranged substantially concentrically as shown in FIG. 2, but its shape is not limited to that shown in the figure.

According to the present invention, the heater 5 is spaced a predetermined distance G from the upstream end surface (front end surface) of the trap material 3, as shown in an enlarged view in FIG. Since the smaller G is, the less electric power is required to ignite the heater, it is preferable to make it as small as possible without causing contact between the heater 5 and trap material 3 even when subjected to engine vibrations.

A specific structural example of the spacer support member 10 for fixing and holding the heater to the trap container 1 with a predetermined gap G from the front end surface of the trap material 3 is shown in FIGS. 4A and subsequent figures.

The heater 5 is held, for example, by an annular support insulator (ceramic) 11 fixed to the trap container 1 by bolts 18 around its outer periphery, as shown in FIG. The support insulator 11 has, for example, six arms 13 extending radially from the center, and each arm has grooves 19 formed in the number corresponding to the number of heater wires passing through the arms. Inserted (4th
A, 4B). After a heater wire is inserted into each arm 13, a spacer cap insulator (ceramic) 17 is fixed with a heat-resistant inorganic adhesive such as Aron Ceramic (trade name). A groove 21 corresponding to the support insulator 11 is also formed in the spacer cap insulator 17, and both grooves 19 and 21 form a cavity in which a heater wire (for example, 8A) is enclosed. Further, the wall thickness t of the spacer cap insulator 17 substantially guarantees the gap G between the trap material and the heater wire.

5A and 5B show a different embodiment from those shown in FIGS. 4A and 4B. It is deeper than 19. That is, in the embodiment shown in FIGS. 4A and 4B, the space for holding the heater wire is formed by the two opposing grooves 19 and 21, but in FIGS. 5A and 5B, the space for holding the heater wire is formed by the groove 25. formed by chisel. The support rod 29 prevents the heater wire from coming off. For this reason, a longitudinal groove 27 is formed in the support insulator 23 and intersects with the groove 25. The support rod 29 may be, for example, a heat-resistant stainless steel rod 29a inserted into an insulator tube (alumina porcelain tube) 29.
It is sufficient that at least a portion of the insulator tube 29 corresponding to the support insulator 23 is present. The support rod 29 is fixed to the support insulator 23 with an inorganic adhesive or the like. In the case of the embodiment shown in FIGS. 5A and 5B, the support rod 29
The diameter D of the insulator tube 29 provides the gap G. According to this embodiment, since a metal rod is inserted into the center of the support rod, the impact resistance and vibration resistance are stronger than that of the ceramic unit spacer cap insulator shown in FIGS. 4A and 4B.

In the embodiment shown in FIG. 6, the groove 33 formed in the support insulator 31 is in the form of a dovetail groove, into which a presser piece 35 of a corresponding shape (made of alumina porcelain, stainless steel heat-resistant metal, etc.) is fitted. A concave groove 39 into which the heater wire 8A is inserted is formed in the presser sesame 35. In the embodiment shown in FIG. 6, each presser sesame is fitted into the corresponding groove 33 without coming out of the groove 33 due to its dovetail groove shape, so no fixing means is required, but preferably an inorganic adhesive is used. Alternatively, stopper claws (not shown) may be provided on both sides of the groove 33 of the support insulator 31 to prevent the presser sesame 35 from slipping back and forth from the groove 33 to ensure secure fixation. In this example, G
is determined by the wall thickness t' of the presser sesame 35.

In the embodiment shown in FIGS. 7A and 7B, the support insulator is composed of two support insulators 41A and 41B. The grooves 43 and 45 formed in the support insulators 41A and 41B have different inclinations so that the heater wire can be securely inserted into the common bottom of the grooves 43 and 45. In FIGS. 7A and 7B, the groove 45 is a vertical groove, whereas the groove 43 is an inclined groove. Therefore, the heater wire is inserted into these grooves 4.
If it is inserted across 3 and 45, it will no longer be the 7th B.
In the figure, it does not come out to the right. Therefore, if the two support insulators 41, 41B are bonded together in this state, the heater wire can be held immovably. In this embodiment, G is determined by the depth of the grooves 45 and 43.

In the embodiment shown in FIG. 8, the support insulator 51 is formed with a groove 53 having a bottom formed by a rounded curve as shown. The groove 53 has a notch 54, and the heater wire is fitted into the notch 54 in advance while being biased in the direction of arrow A. That is, tension in the direction of arrow A always acts on the heater wire, and as a result, the heater wire does not come out of the notch 54 in the groove 53. Note that it is necessary to take into consideration during assembly that the direction in which the heater wire expands during heating is also in the direction of the arrow. In this embodiment, G is determined by the wall thickness t'' of the top portion of the support insulator 51 forming the groove 53 and the notch 54.

As described above, according to the present invention, by assembling the heater with a predetermined distance from the upstream end face of the trap material using a heat-resistant support member that also serves as a spacer, all of the drawbacks mentioned at the beginning can be eliminated. . Further, according to the present invention, since the heater wire can be easily assembled into the trap container using the support member, the workability of assembling the trap as a whole can be improved.

[Brief explanation of the drawing]

Fig. 1 is a longitudinal sectional view of a particulate trap according to the present invention, Fig. 2 is a view taken along the - line in Fig. 1, Fig. 3 is an enlarged view of the main parts of Fig. 1, Fig. 4A and 4B is a perspective view and a side view showing a first embodiment of the support member according to the present invention, and FIGS. 5A and 5B are views similar to FIGS. 4A and 4B showing a second embodiment of the support member. , FIG. 6 similarly shows the third embodiment, FIGS. 7A and 7B similarly show the fourth embodiment, and FIG. 8 similarly shows the fifth embodiment. 1... Trap container, 3... Trap material, 5...
...Heater, 10...Support member.

Claims (1)

[Scope of utility model registration request] A trap container containing a built-in trap material for collecting exhaust particulates from a diesel engine and a heating element having a heater wire for igniting and burning the exhaust particulates collected by the trap material is installed in the exhaust pipe line of the diesel engine. In the exhaust gas purification device, the heating element is mounted from the upstream end face of the collection material when viewed in the exhaust gas flow direction when exhaust particulates are ignited and burned by a heat-resistant support member having a concave groove into which a heater wire is inserted and held. An exhaust gas purification device for a diesel engine, characterized in that it is installed in a trap container at a predetermined distance.