JPH024768B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a heater for regenerating a filter member by burning and removing particulates collected by a filter member installed in an exhaust gas passage of an internal combustion engine.

In recent years, diesel engines have come to be used as vehicle engines due to their good fuel efficiency, but compared to gasoline engines they emit a larger amount of carbon particles, or smoke, so it is necessary to reduce the amount of smoke emitted. There is a need for an effective particulate purification device.

Conventionally, this type of device has installed a particulate collector equipped with a heat-resistant filter member, such as a filter member made of porous ceramic or metal fiber, in the exhaust system of the engine, and the filter member is used to collect and collect particulates. There are things to collect. However, in this device, as the accumulation of fine particles on the surface of the filter member progresses, the ventilation resistance of the filter member increases, resulting in a decrease in the engine output, and agglomerates of particles begin to fall off the surface of the filter member, causing the function of the filter member to deteriorate. In order to reduce the amount of particles, it is necessary to remove the collected particles from the filter member at appropriate intervals and regenerate the filter member.

It is known that most of the fine particles deposited on the filter member are carbon particles containing fuel components, and can be burned and removed by heating to about 580° C. or higher. The exhaust gas temperature of a diesel engine is considerably lower than that of a gasoline engine, and does not exceed 580°C except when driving at high speeds. Therefore, a method is needed to increase the exhaust gas temperature and burn the particulates collected in the filter member. It is proposed that it be equipped.

That is, an electric heater is provided on the exhaust gas inflow side end face of a filter member that collects particulates, and when a predetermined amount of particulates are attached to and collected on the filter member, the electric heater is heated by applying electricity to cause the particulates to be captured on the filter member. The filter member is regenerated by burning off the collected particles. This regeneration is carried out under the flow of exhaust gas, and the electric power input to the electric heater is required to be 30 to 50 watts/cm ² per end area of the filter.

By the way, in diesel engines with a displacement of about 2000 cc, a filter member with an end face diameter of about 11 cm is usually used in view of particulate collection efficiency, ventilation resistance, etc., and the entire surface of the filter member is heated at once. To reproduce it, a large amount of power of 2.8 to 4.7KW is required based on the above power density. It is impossible to supply such a large amount of power with a normal car battery, so a method is used in which the electric heater installed on the end face of the filter member is divided into multiple parts and each heater is energized in turn. If a large number of heaters are provided in order to reduce the burden on the battery, the number of lead wires and relays that control energization will increase accordingly, making the energization circuit complex and increasing costs.

The present invention has been made with the aim of solving the above-mentioned problems, and is provided with a power supply side relay and a ground side relay, the power supply side conductor is connected to the power supply line through the contact of the power supply side relay, and the ground side conductor is connected to the power supply line through the contact point of the power supply side relay. Connect to the ground wire through the contact of the above earth side relay, connect a heater between the above two conductors so that both ends are not connected to the same conductor, and connect the above power supply side relay contact and the earth side relay. The present invention aims to provide a heater energization circuit that can control energization of a large number of heaters with a small number of relays by sequentially closing different combinations of contacts.

The present invention will be explained below with reference to illustrated embodiments.

FIG. 1 is a configuration diagram of an internal combustion engine exhaust system in which a particulate purification device equipped with a heater according to the present invention is installed in its exhaust gas passage, where E is the internal combustion engine, 4 is its exhaust manifold pipe,
5 is an exhaust pipe, A is a particulate purification device, and the device A is mainly composed of a container 3, a filter member 2 housed therein, and an electric heater 1 joined to the upstream end surface of the member 2. . Here 1
0 is a terminal for power supply.

A differential pressure sensor 6 is attached to the container 3 to detect the differential pressure upstream and downstream of the filter member 2. This differential pressure sensor 6 is connected to a relay 8 via a control device 7, and the electric heater 1 is connected to a relay 8 via a control device 7.
It is connected to the battery 9 via.

As the exhaust gas containing particles passes through the filter member 2, the particles are collected. As the collection progresses, the ventilation resistance of the filter member 2 gradually increases, and the differential pressure increases. When the differential pressure reaches a predetermined value and is detected by the differential pressure sensor 6, the relay 8 is energized by a signal from the control device 7, and the electric heater 1 is energized from the battery 9 via the terminal 10 through its contacts. be done. The electric heater 1 becomes red hot and combustion of particulates adhering to the heater surface and the filter member 2 in contact with the heater 1 begins. When the particulates near the electric heater 1 are combusted, the combustion heat is sent downstream by the exhaust gas flow, and the collected particulates are sequentially combusted and removed downstream.

FIG. 2 schematically shows the regeneration of the filter member, in which an electric heater such as a nichrome wire is sandwiched between the ceramic honeycomb structure 11 and the end face 21 on the exhaust gas inflow side of the filter member 2. 1
is provided. A large number of heaters 1 are actually provided so as to cover the entire end surface, and each heater 1 is held by a honeycomb structure. As shown in the figure, the heater 1 is usually formed into a wave shape to increase the power density per unit area, and when it is energized while exhaust gas is flowing, particulates on the downstream side of the part of the filter member 2 in contact with the heater 1 are burned and purified. (area 2a in the figure),
The area 2b around it is left unpurified.
Therefore, in order to burn the particles in the entire filter member, it is necessary to provide a heater on almost the entire end face of the filter member 2.

FIG. 3 shows the arrangement of conventional heaters. Nine heaters 1a, 1b, 1c,
1d, 1e, 1f, 1g, 1h, and 1j are provided, one end of each heater 1a to 1j is grounded to the container 3, and the other end is connected to a power supply side conductor 92 extending outside the container 3 through the current-carrying terminal 10. It's connected.

FIG. 4 shows a current supply circuit for conventional heaters 1a to 1j. The nine power supply conductors 92 are connected to the power supply line 91 through the contacts of the nine relays 8, respectively. The control device 7 and each relay 8 are connected by a control line 71, and the relays 8 sequentially close their contacts in response to a control signal from the control device 7 that receives a signal from the differential pressure sensor 6 (see Figure 1). and each corresponding heater 1a
1j, power is supplied from the battery 9 to the power supply line 91 and the power supply conductor 92 via the current-carrying terminal 10.

As described above, the conventional heater circuit requires the same number of relays as the electric heaters to be installed, and the number of lead wires increases accordingly, which increases the wiring effort and increases the cost of the device.

Now, FIG. 5 shows the arrangement of the heater of the present invention. Nine heaters 1a, 1b, 1 are provided on the exhaust gas inflow side end surface 21 of the filter member 2 so as to cover the entire end surface.
c, 1d, 1e, 1f, 1g, 1h, and 1j are provided. Also, the power supply side conductors 92a, 92b, 92c
And ground side conducting wires 92d, 92e, and 92f are laid. The heaters 1a to 1j are connected to the same power supply, for example, one end of the heaters 1a, 1d, and 1g is connected to a common power supply conductor 92a, and the other ends of the heaters 1a, 1d, and 1g are connected to different ground conductors 92d, 92e, and 92f, respectively. Side conductor wires 92a, 92
Heater 1a~ whose one end is connected to b, 92c
1j, the other end is a different ground side conductor 92d,
It is connected to 92e and 92f. Each of the above conductive wires 92
a, 92b, 92c, 92d, 92e, and 92f extend outside the container 3 through the current-carrying terminal 10.

FIG. 6 shows an energizing circuit for heaters 1a to 1j of the present invention, in which power supply relays 8a, 8b, 8c and ground relays 8d, 8e, 8f are provided, and the power supply conductors 92a, 92b, 92c are connected to the power supply relays. 8a,
It is connected to a power supply line 91 via contacts 8b and 8c. This power supply line 91 reaches the positive electrode of the battery 9. In addition, the earth side conductors 92d, 92e, 92
f is connected to the ground wire E via the contacts of the ground side relays 8d, 8e, and 8f. This ground wire is grounded. Control lines 71a to 71f are connected to relays 8a, 8b, 8c, 8d, and
It has reached 8e and 8f.

In the heater energizing circuit connected as described above, when the control device 7 receives a signal from the differential pressure sensor 6 (see Figure 1), an output signal is generated through the control lines 71a and 71d, and the relays 8a and 8d are activated. The contact closes. As a result, from the positive terminal of the battery 9, the power supply line 91, the contact of the relay 8a, the power supply side conductor 92a, the heater 1a, the ground side conductor 92d,
Heater 1 is connected to the relay 8d contact and ground wire E route.
A is energized. When the heater 1a is energized for a certain period of time, the output signal of the control line 71a disappears, and the control line 7
An output signal is generated by 1b, and the contacts of relay 8b are newly closed instead of relay 8a. At this time, the contacts of the relay 8d remain closed, and the heater 1b is newly energized instead of the heater 1a. All power supply side relays 8a, 8b, 8c and earth side relays 8d, 8 are sequentially controlled by control signals.
By closing the contacts of combinations e and 8f, the nine heaters 1a to 1j are sequentially energized and heated, and the fine particles collected on the filter member 2 on the downstream side of each heater 1a to 1j are sequentially heated. After combustion and purification, the filter member 2 is regenerated.

By creating such a circuit, the conventional circuit required 9 relays to sequentially energize the 9 heaters, whereas the circuit of the present invention requires 6 relays.
Only one relay is required. Furthermore, even if the number of heaters increases to 12 and 16, according to the circuit of the present invention, there will be 7 and 16 heaters, respectively.
It is sufficient to provide 8 relays.

As explained above, the electric heater energizing circuit of the present invention includes a plurality of power supply conductors connected to a power supply line via a power supply relay contact, and a plurality of ground conductors connected to a ground line through a ground relay contact. Lay the conductors, connect both ends of the heater between the above conductors so that both ends are not connected to the same power supply conductor and the same earth conductor, and make sure that the power supply relay contact and the earth relay contact are different. By sequentially closing them in combination, it is possible to significantly reduce the number of relays needed to sequentially energize a large number of heaters installed in a particulate purification device, resulting in a reduction in wiring man-hours and a significant cost reduction. .

[Brief explanation of drawings]

Figure 1 is a configuration diagram of an exhaust system of an internal combustion engine with a particulate purification device interposed in the middle of the exhaust pipe, and Figure 2 shows a filter partially regenerated by an electric heater installed on the exhaust gas inlet end of the filter member. Figures 3 and 4, which schematically show the members, show conventional heaters. Figure 3 is a layout diagram of the heater provided on the end face of the exhaust gas inflow side of the filter member, and Figure 4 shows the heater. Figures 5 and 6 show the heater of the present invention. Figure 5 is a layout diagram of the heater provided on the end face of the exhaust gas inflow side of the filter member, and Figure 6 is a circuit diagram of the heater. It is a energization circuit diagram. A... Particulate purification device, 1a, 1b, 1c, 1
d, 1e, 1f, 1g, 1h, 1j...electric heater, 2...filter member, 21...exhaust gas inflow side end surface of filter member, 7...control device, 8a,
8b, 8c...Power supply side relay, 8d, 8e, 8f
...Earth side relay, 9...Battery, 91...
Power supply lines, 92a, 92b, 92c...Power supply side conductors, 92d, 92e, 92f...Earth side conductors.

Claims (1)

[Claims] 1. A filter member for collecting particulates in the exhaust gas is provided in the exhaust gas passage of the internal combustion engine, and a plurality of filter members are provided on the exhaust gas inflow side end face of the filter member for burning and purifying the particulates collected by the filter member. In a particulate purification device equipped with an electric heater, a plurality of power supply conductors and a plurality of ground conductors are provided, the power supply conductor is connected to the power supply line via a power supply relay contact, and the ground conductor is connected to the power supply wire through a power supply relay contact. Each electric heater is connected to a ground wire via a relay contact, and both ends of each of the electric heaters are connected between the power supply conductor and the ground conductor, and the other ends of the heaters connected to the same power supply conductor are connected to separate earths. The other ends of the heaters, which are connected to the side conductor and connected to the same ground side conductor, are connected to separate feed side conductors, while the above-mentioned feed side relay contacts and earth side relay contacts are connected to different combinations. 1. An energizing circuit for an electric heater for a particulate purifier, characterized in that a control device is provided for energizing a power feeding side relay and a grounding side relay so as to sequentially close the relay.