JPH0424093Y2 - - Google Patents

Description

[Detailed description of the invention] [Field of industrial application] The present invention relates to an exhaust gas purification device for a diesel engine, and more specifically, to a back pressure measuring device for an exhaust back pressure measuring device for a diesel exhaust solid particulate collection device in which a filter can be regenerated. Regarding pressure port structure.

[Conventional technology]

BACKGROUND OF THE INVENTION Exhaust gas purification devices that purify diesel exhaust gas by collecting solid particulate emissions such as exhaust black particles contained in the exhaust gas of diesel engines are well known. Such a purification device usually consists of a trap using a heat-resistant porous filter made of ceramic or the like.
An example of a conventional exhaust solid particulate collector system will be described with reference to FIG. 8. 1 is a diesel engine, 2 is an exhaust manifold, 3 and 4 are exhaust pipes, and 5 is a collector. Housing 6 of collector 5
A monolithic filter 7 is stored inside.
Solid particulates in diesel exhaust gas can be collected mainly by the principle of collision collection.

If the solid particles collected during use of the collector accumulate in the filter, the filter will become clogged, increasing ventilation resistance and reducing the collection efficiency, so the filter must be regenerated at an appropriate time or periodically. Must be. Since the solid particulates in diesel exhaust are mainly composed of carbon and are therefore flammable, the filter can be regenerated by igniting some of the solid particulates that have accumulated in the filter and causing the fire to spread and blow over the entire area of the filter. Is possible. In the conventional example shown in FIG. 8, an electric heater 8 is provided in contact with or in close proximity to the upstream end face of the filter 7, and a control circuit 9 closes a relay 10 at an appropriate time to energize the heater 8 for a certain period of time. By heating the filter, the solid particles in the filter are ignited. In order to determine when to regenerate this filter, in the conventional example described above, a back pressure detection port 11 is bored in the exhaust pipe 3, and the back pressure is guided to a back pressure sensor 13 through a back pressure transmission pipe 12. The back pressure value is converted into a current value using a piezoelectric resistance element or a strain gauge, and this is sent to the control circuit 9.
The playback time is detected by comparing it with the set value. Generally, an introduction cap for taking in exhaust back pressure is attached to the detection port, and a back pressure transmission pipe is connected to this cap.

In this method of determining the filter regeneration timing by detecting the back pressure of exhaust gas, the structure of the back pressure introduction cap that is attached to the back pressure detection port bored in the exhaust pipe is extremely important. That is, during long-term use, solid particles and corrosive condensed components in the exhaust gas may act on the resistance element of the back pressure sensor, deteriorating the performance of the element. In addition, solid particulates and condensate also adhere to the inner walls of detection ports and back pressure transmission pipes, and if the amount of adhesion increases, the ports and pipes will eventually become clogged, making it difficult for the back pressure sensor to detect accurate pressure. This is because the reliability of the back pressure sensor is significantly impaired. Therefore, on the one hand, the back pressure introduction cap must be able to transmit exhaust gas pressure smoothly, and on the other hand, it must be able to completely block out solid particles and condensable components in the exhaust gas. .

In order to filter exhaust particulates in the exhaust gas and introduce only clean exhaust gas into the detection port, the particulates are filtered with a honeycomb filter, and the particulates adhering to the honeycomb filter are incinerated by heating with an electric heater. A back pressure introducing structure for regenerating a honeycomb filter is disclosed in Japanese Utility Model Application Publication No. 163617/1983.

In the back pressure introduction part structure disclosed in the above publication, the terminal of the lead wire connected to the heater may break or come off from the welded part with the back pressure transmission pipe due to the influence of engine vibration. In order to solve this problem, the present applicant proposed an improved back pressure port structure (see Utility Model Application No. 37467/1983).

The back pressure port structure of the above-mentioned Utility Application No. 61-37467 is as follows:
As shown in FIGS. 9 and 10, there is a cap part 15 that faces into the exhaust gas and constitutes an exhaust gas introduction passage for introducing the exhaust gas, and a cap part 15 that holds the cap part and directs the exhaust gas introduced from the cap part to the outside. It has a hollow housing 17 equipped with an outer tube 16 for guiding, and a heater 18 provided in an exhaust passage connecting the base portion 15 and the outer tube 16 to burn and remove attached exhaust particulates, and the heater 18 is connected to an external power source. The heater terminal 18a connected to the outer tube 16 is connected to a pipe 20 fixedly held within the outer tube 16 via a ceramic spacer 19.

[Problem that the invention attempts to solve]

In the back pressure port structure of Utility Application No. 1983-37467 proposed by the present applicant, one terminal of the heater 18 is grounded to the body of the back pressure port.
The other positive terminal has a structure that is shared with a rear pipe 20 for connection to a pressure introduction rubber pipe (not shown) to the back pressure detection sensor. Therefore, the positive terminal is exposed to the outside and there is a risk of it being shot due to contact with other parts.

In addition, the overall length of the back pressure port becomes longer than necessary due to the extraction part of the lead wire 21, resulting in an increase in weight and
This leads to an increase in costs and also increases the number of problems such as damage due to vibration.

[Means for solving problems]

In order to solve the above problems, the present invention includes an exhaust gas introduction pipe that opens into the exhaust gas passage, a heater that is installed in the introduction pipe to burn particulates in the exhaust gas, and a heater to exhaust the exhaust gas from the introduction pipe. A rear pipe leading to a back pressure detection sensor and a connecting pipe connecting the rear pipe and the back pressure detection sensor are provided, the rear pipe and the heater are connected by a lead wire, and the lead wire is connected to an external power source. In the back pressure port structure of the exhaust gas back pressure measuring device, a lead wire is fixed along the inner wall of the connecting pipe, the connecting pipe is fitted to the rear pipe, and the lead wire on the inner wall of the connecting pipe is connected to the outside. A back pressure port structure is provided for connection to a power source.

〔Example〕

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 shows the entire embodiment of the present invention. In the same figure, reference numeral 30 is an exhaust gas passage of the engine, and a housing 3 with a flange or screw structure is shown.
A back pressure port is attached to the exhaust gas passage 30 by 1. A hollow base 32 is inserted into the lower part of the housing 31, and the lower end of the base 32 is exposed to the exhaust gas flowing through the exhaust gas passage 30. A hollow ceramic heater 33 is fixedly attached within the housing 31 to burn and remove exhaust particulates in the exhaust gas passing through the hollow ceramic heater 33.

The heater 33 is joined to the holding fitting 34 by an appropriate method, and the heater ground is grounded to the holding fitting 34 at this point. A positive lead wire 35 is connected near the tip of the heater 33. An insulating holder 36 made of ceramic or the like is placed above the holding fitting 34, a rear pipe 37 is assembled above the insulating holder 36, and a positive terminal 35 of the heater is joined to one end of the rear pipe 37 by spot welding 38 or the like.

Next, the rear cover 39 is arranged outside the insulating holder 36 and assembled into the housing 31 together with the base 32. A talc 40 for airtightness and a ring 41 are interposed between the housing 31 and the rear cover 39, and the housing The housing 31, the base 32, and the rear cover 39 are integrated by curling the upper end of the housing 31. Finally, the rubber 42 is fitted to the outside of the rear pipe 37, and the upper end of the rear cover 39 is caulked to fix the rear pipe 37 and maintain its airtightness.

A pressure introducing rubber pipe 50 for introducing exhaust gas back pressure to the back pressure detection sensor is fitted in an airtight manner on the outside of this rear pipe 37.

Referring to FIGS. 2 and 3, a lead wire 52 is fixed to the inner wall of the main body 51 of the pressure introduction rubber pipe 50 along its axial direction.

The pressure introduction rubber pipe 50 is manufactured as shown in FIG.

A cylindrical center shaft 53 having a partially flat surface 53a
The metal wire that will become the lead wire 52 is placed on the flat surface 53a.
An outer mold 54 having a cylindrical shape as a whole is placed on top of the
cover with At this time, a mold release agent is applied to the outer periphery of the center shaft 53 and the inner periphery of the outer mold 54, respectively. After the rubber is poured and sufficiently hardened, the inner shaft 53 and outer mold 54 are pulled out to obtain the rubber pipe 50 shown in FIG. 2. In order to improve contact with the rubber pipe body 51, the lead wire 52 preferably has a flat portion rather than a cylindrical shape, and may have two or more lead wires. Furthermore, the lead wire 52 may be attached in a spiral manner. Rubber pipe 50 made in this way
is fitted onto the outer periphery of the rear pipe 37 shown in FIG. 1, and becomes a rubber pipe with a built-in positive terminal.

As shown in FIG. 5, a joint 55 for taking out the lead wire 52 is provided in the middle of the rubber pipe 50, and a voltage is applied to the heater 33 through the joint 55.

The structure of the joint 55, as shown in FIG.
A lead wire 58 and a connector 59 are connected to the terminal. From this joint 55 onwards is a normal rubber pipe 6.
0 to connect to a pressure sensor (not shown).

Since the present embodiment has the above-described configuration, the positive terminal for the heater 33 is not exposed to the outside, and contact with other parts is avoided, thereby eliminating the risk of shooting. In addition, there is no need for a structure for taking out lead wires, and the overall length can be shortened, making it more resistant to vibration. Furthermore, the reliability is improved because the lead wires do not come off.

FIG. 6 shows a structure for preventing the pressure introduction rubber pipe 50 from coming off and contact failure. Before caulking the rear cover 39 at the back pressure port shown in FIG. 1, the rubber pipe 50 is fitted and connected to the rear pipe 37. Then, cover the upper end of the rear cover 39 and the lower end of the rubber pipe 50 with the protective cover 61,
The lower end and upper end of this protective cover 61 are caulked 6.
Apply 2,63. The lower end caulking 62 is performed at the same position as the caulking part of the rear cover 39 shown in FIG.
The caulking 63 at the upper end is the lead wire 5 of the rubber pipe 50
By doing this from above 2, poor contact between the rear pipe 37 and the lead wire 52 can be prevented.

FIG. 7 shows an example of the connection between the positive terminal of the heater and the back pressure detection sensor, in which the positive terminal of the heater is taken out from the back pressure sensor body. The back pressure sensor main body 70 is provided with a back pressure introduction port 71, but since this introduction port 71 is generally made of metal, it is not preferable to directly connect the heater terminal. Therefore, a metal port 73 is provided via an insulating resin port 72, and these are connected to the resin 7
4, and the ports 72 and 73 are fixed. At this time, it is convenient to attach a lead wire 75 to the metal port 73 in advance and take it out together with the lead wire for the back pressure sensor. In addition, G in the same figure
is the ground, V _IN is the sensor drive voltage, and V _OUT is the sensor output.

[Effect of idea]

According to the present invention, since the positive terminal for the heater is not exposed, contact with other parts is avoided, and there is no risk of it being thrown out.

Further, a structure for taking out the lead wire is not required, and the overall length of the back pressure port can be shortened. Therefore, it is resistant to vibrations, and problems such as lead wires coming off do not occur. Furthermore, the overall weight is reduced, and the number of component parts is reduced, resulting in cost reduction.

Furthermore, when mounted on a vehicle, there is no particular need to protect the lead wires, making installation on the vehicle easy.

[Brief explanation of the drawing]

Fig. 1 is a vertical cross-sectional view of the entire embodiment of the present invention;
The figure is an enlarged longitudinal sectional front view of the pressure introduction rubber pipe in the embodiment same as above, Fig. 3 is a cross-sectional plan view of the same, Fig. 4 is an explanatory view showing the manufacturing method of the same rubber pipe, and Fig. 5 is a joint for lead wire extraction from the same rubber pipe. FIG. 6 is a vertical cross-sectional view showing an example of the joint between the same rubber pipe and the rear pipe, FIG. 7 is a vertical cross-sectional view showing an example of the connection between the heater positive terminal and the back pressure detection sensor, FIG. 8 is a conceptual diagram of an exhaust solid particulate collection device, FIG. 9 is an enlarged vertical sectional view of the main part of a conventional back pressure port, and FIG. 10 is a front view showing the entire back pressure port. 5... Collector, 11... Back pressure detection port, 13
... Back pressure sensor, 15 ... Base part, 16 ... Outer tube, 17 ... Hollow housing, 18 ... Heater,
20... Pipe, 21... Lead wire, 30... Exhaust passage, 31... Housing, 32... Base, 3
3...Heater, 35...Lead wire, 37...Rear pipe, 39...Rear cover, 50...Pressure introduction rubber pipe, 52...Lead wire, 55...Joint,
60...Rubber pipe, 61...Protective cover, 70
... Back pressure sensor body, 71 ... Back pressure introduction port,
75... Lead wire.

Claims (1)

[Scope of utility model registration request] An exhaust gas introduction pipe opening into an exhaust gas passage, a heater installed in the introduction pipe to burn particulates in the exhaust gas, a rear pipe that guides the exhaust gas from the introduction pipe to an exhaust back pressure detection sensor, and the rear pipe. A back pressure of an exhaust gas back pressure measuring device, comprising a connecting pipe connecting the back pressure detection sensor, the rear pipe and the heater being connected by a lead wire, and the lead wire being connected to an external power source. In the port structure, a lead wire is fixed along the inner wall of the connecting pipe, the connecting pipe is fitted to the rear pipe, and the lead wire on the inner wall of the connecting pipe is connected to an external power source.