JPS6335154Y2 - - Google Patents

Description

[Detailed description of the invention] (Field of industrial application) The present invention relates to an exhaust purification device for automobile diesel engines, and in particular, the particulate components in the exhaust are collected by a filter member, and the particulates collected by the filter member are This invention relates to an improvement in a device for removing components by combustion.

(Prior Art) Generally, particulate matter is mixed into the exhaust gas of a diesel engine, which is generated when part of the fuel decomposes due to the high temperature during the combustion process and part of the carbon is liberated, and this particulate matter is discharged as black smoke in the exhaust gas. For this reason, as part of the exhaust gas purification measures for diesel engines, an exhaust gas purification device has already been developed in which a breathable filter member made of ceramics or the like in a honeycomb shape is disposed in the exhaust passage of the engine, and the particulate matter mixed into the exhaust gas is collected by the filter member while the exhaust gas passes through the filter member.

When an engine is operated for a long period of time in an exhaust purification device equipped with such a filter member, the filter member becomes clogged due to the accumulation of particulate components, which increases the back pressure of the engine and causes a decrease in output. There is a problem.

Therefore, as disclosed in Japanese Patent Application Laid-Open No. 55-131518, an electric heating element made of nichrome wire or the like is attached to the filter member, and the electric heating element is energized periodically or when clogging occurs. It has been proposed to burn the particulate components deposited on the filter member and eliminate clogging of the filter member.

However, in this prior example, it is preferable to apply a high voltage of 24 V to increase the amount of heat generated in order to cause the electric heating element to burn the particulate components in a short time, but various electrical components are used in automobiles. However, there was a problem in that making all of these electrical components 24V specifications would unnecessarily increase the cost of the electrical components. Therefore, the electric heating element may include, for example,
Powered by 24V power supply voltage, other electrical components are connected to normal
It is preferable to energize with a power supply voltage of 12V.

(Purpose of the invention) The purpose of the invention is to apply a high voltage to the electric heating element that burns and removes particulate components deposited on the filter member to achieve rapid heating, while applying normal voltage to other electrical components. An object of the present invention is to provide an exhaust purification device for a diesel engine that can perform the following steps.

(Structure of the invention) The exhaust gas purification device for a diesel engine according to the invention has the following structure. In other words, in a diesel engine exhaust purification device that uses an electric heating element to burn and remove particulate components collected in a filter member disposed in the exhaust passage of the engine, multiple power sources are selectively connected in series and parallel. an operation control device is provided to output an energization signal to the electric heating element, and the plurality of power supplies are connected in series by the energization control device in response to the operation control signal of the operation control device. A power supply voltage connected in series is applied to the electric heating element.

(Embodiments) <First Embodiment> A first embodiment of the present invention will be described with reference to FIGS. 1 to 3. A filter accommodating portion 2 is formed in the exhaust passage 1 of the diesel engine shown in FIG. It has an internal volume of . A filter member 3 that collects particulate components made of carbon in the exhaust gas is housed in the filter housing part 2, and this filter member 3 is made of highly breathable porous ceramic called cordierite. It is formed into a honeycomb shape having a large number of small holes 3a and 3b passing through it in the axial direction. The upstream open ends of the small holes 3a of the filter member 3 are closed with blind plugs 4, and the downstream open ends of the remaining small holes 3b are closed with blind plugs 4. Exhaust gas flowing from the upstream side flows into the small hole 3b whose downstream open end is closed and the upstream side is open, and after particulate components are collected by the partition wall 3c, the upstream open end is closed and the downstream side is open. It is designed to be discharged to the downstream side of the exhaust passage 1 through the small hole 3a.
Further, at the upstream end of the filter member 3, a heater 5, which is an electric heating element, is inserted through the blind plug 4 and into the small hole 3a. The heater 5 is made of nichrome wire, for example, and is energized to heat and burn particulate components deposited on the filter member 3 to remove them.

A bypass passage 6 is connected to the exhaust passage 1, which bypasses the filter member 3 and communicates the upstream side and the downstream side of the filter member 3. A bypass control valve 7 is inserted in the middle of this bypass passage 6, and this bypass control valve 7 controls the bypass passage 6.
It is designed to control opening and closing. One end of a pressure guide pipe 8 is connected to the bypass control valve 7 , and the other end of the pressure pipe 8 is connected to a vacuum pump 9 . In addition, a three-way valve 10 is located in the middle of the impulse pipe 8.
is inserted, and by switching the three-way valve 10, the negative pressure acting on the bypass control valve 7 is adjusted to open and close the bypass control valve 7. One end of a secondary air passage 11 is connected to the upstream side of the filter member 3 of the exhaust passage 1, and an air pump 12 is connected to the other end of the secondary air passage 11.
is connected to the secondary air passage 11, and an on-off valve 13 is inserted in the middle of the secondary air passage 11.

A temperature sensor A14 is inserted into the filter housing part 2 on the downstream side of the filter member 3 of the filter housing part 2, and a temperature sensor B15 is inserted into the filter housing part 2 on the upstream side of the filter member 3. . The temperature sensor A14 is the filter member 3
The temperature of the exhaust gas on the downstream side is measured to detect whether or not the particulate components deposited on the partition wall 3c are being burned by the heater 5. The temperature sensor B15 measures the temperature of the exhaust gas on the upstream side of the filter member 3 to detect the temperature of the filter member 3 heated by the heater 5.

In the figure, reference numerals 16a and 16b are on-vehicle batteries serving as power sources, each having a voltage of 12V.
The negative electrode side of this battery 16a is grounded to the body of the automobile, and the positive electrode side is connected via a key switch 17 to various electrical components 18 installed in the automobile. In addition, the positive terminal side of the battery 16b is connected to the battery 16 through the OFF terminal of the relay A19.
It is connected to the positive electrode side of a, and on the other hand, the battery 16
The negative electrode side of B is connected to the negative electrode side of battery 16a via the OFF terminal of relay B20. The ON terminal of the relay A19 is connected to the heater 5 via the relay C21, and the ON terminal of the relay B20 is connected to the heater 5 via the relay C21.
The terminal is connected to the positive electrode side of the battery 16a.

These relay A19, relay B20, relay C
21 is energized to turn on and off; relay C21 is wired to be energized by actuation control device 22; relay A19 and relay B20 are wired to be energized by energization control device 23. ing.

The operation control device 22 includes a clogging sensor 24.
A clogging detection signal of the filter member 3 is inputted from the clogging sensor 24, and the clogging sensor 24 integrates the amount of fuel consumption and outputs a clogging detection signal when the amount of fuel consumption reaches a set value, for example. It is. The detection signals of the temperature sensor A14 and temperature sensor B15 are input to the operation control device 22, and the operation control device 22 energizes the relay C21 when the filter member 3 is clogged based on these three input signals. A signal, that is, an excitation current is outputted, and an operation control signal is outputted to the energization control device 23, and the three-way valve 10 is switched to open the bypass control valve 7, so that the temperature of the heater 5 reaches the level of the particulate component (carbon). Self-combustion temperature T ₁ (approximately 600
℃), a drive signal is output to the air pump 12 to supply secondary air from the secondary air passage 11 to supply oxygen consumed by combustion of the particulate components, and the detection signal of the temperature sensor A14 reaches a predetermined level. When the level exceeds the level and continues for a predetermined time, combustion of the particulate components is completed and the clogging state is eliminated, the excitation current of the relay C21 is cut off.

An operation control signal from the operation control device 22 and a detection signal from the temperature sensor B15 are input to the energization control device 23, and the energization control device 23 determines whether the filter member 3 is clogged or not. The temperature of member 3 is within the heat resistance limit T ₀ (approximately
When the temperature is below 900°C, the relays A19 and B20 are energized and turned ON, and when the temperature of the filter member 3 reaches the heat resistance limit _T0 over time, the relay B20 is turned OFF. .

The operation of the apparatus of the first embodiment configured as described above will be explained with reference to FIGS. 2 and 3. First, in step 25 of FIG. 2, the entire apparatus is initialized, and then in step 26, the detection signal of the clogging sensor 24 is inputted to the operation control device 22. Next, in step 27, it is determined whether or not there is a clogging condition, and if it is not a clogging condition, the process returns to step 26, and if it is a clogging condition, the process proceeds to step 28 and step 32. In this step 28, the operation control device 22 and the energization control device 23 control the relays A19, B20, and C21.
At the same time, the three-way valve 10 is operated to open the bypass control valve 7. Therefore, the batteries 16a and 16b are switched from parallel connection to series connection, and a 24V power supply voltage is applied to the heater 5, which rapidly heats it up, while relay A19 is turned on.
Since it operates, the 12V power supply voltage is applied to the 12V specification electrical component 18 only from the battery 16a. Further, a predetermined amount of exhaust gas is bypassed through the bypass passage 6 without passing through the filter member 3, thereby preventing the exhaust gas from delaying the temperature rise of the heater 5. Such step 28 proceeds to step 29, where the detection signal of the temperature sensor B15 is input to the energization control device 23, and the process proceeds to step 30. In this step 30, the energization control device 23 determines whether the detected temperature T of the filter member 3 is equal to or higher than the heat resistance limit _T0 , and when T≧ _T0 ... is established, the process proceeds to step 31, and the equation is If this is not true, the process returns to step 29.
Then, in step 31, the energization control device 23 turns off only the relay B20, and applies a power supply voltage of 12V to the heater 5 only from the battery 16b. Therefore, as shown in Fig. 3, the temperature T of the filter member 3 rises rapidly since the power supply voltage of 24V is applied at the beginning of energization, and when it reaches the heat resistance limit _T0 , the power supply voltage increases to 12V in time. Because of this switching, the temperature T of the filter member 3 will drop gradually.

At step 32, the detection signal from the temperature sensor B15 is input to the operation control device 22, and the process proceeds to step 33. In this step 33, the filter member 3
It is determined whether the temperature T has reached the self-combustion temperature T ₁ of the particulate component, and if T≧T ₁ . Then, in step 34, the operation control device 22 sends a drive signal to the air pump 12 to drive the air pump 12 to supply secondary air from the secondary air passage 11 into the exhaust gas to replenish oxygen consumed by combustion of particulate components. do. Step 34 and step 31 proceed to step 35, where the detection signal of temperature sensor A14 is input to the operation control device 22, and the process proceeds to step 36. In this step 36, the operation control device 22 controls the filter member 3.
When the exhaust gas temperature downstream of the filter member 3 reaches a predetermined temperature or higher and continues for a predetermined period of time, it is determined that the combustion removal of particulate components has been completed, and the process proceeds to step 37. However, if the clogging has not been cleared, proceed to step 3.
Cycle to 5. Then, in step 37, the operation control device 22 turns off the relay C21 to cut off the power supply to the heater 5, switches the three-way valve 10 to close the bypass passage 6, and stops the air pump 12 to supply secondary air. Stop supply. Further, the operation control device 22 cuts off the operation control signal of the energization control device 23, and the energization control device 23 turns off the relay A9.
Normal battery 16a, 16b with OFF operation
A power supply voltage of 12V is applied to the electrical component 18 while the two are connected in parallel.

The device of the first embodiment described above can provide the following effects. First, the filter member 3 becomes clogged and the heater 5 heats the filter member 3. At the initial stage of energization, a power supply voltage of 24V is applied to the heater 5, while a power supply voltage of 12V is applied to the electrical component 18. . Therefore, the heater 5 is the filter member 3
In addition to rapidly heating the battery and burning off accumulated particulate components in a short period of time, the electrical components 18 are powered by inexpensive 12V
Specifications can be used to reduce costs.

Next, when the filter member 3 is heated to the heat resistance limit T ₀ by the energization control device 23, the relay B20
Since the filter member 3 is turned off and the power supply voltage is switched to 12V, the filter member 3 will not be heated above T ₀ and the service life of the filter member 3 can be extended.

When the temperature of the filter member 3 reaches the self-combustion temperature _T1 of the particulate component, the secondary air passage 1
Since the secondary air is supplied from the first air source, oxygen consumed in the combustion of the particulate components can be replenished, and the particulate components can be burned and removed in a shorter time.

<Second Embodiment> A second embodiment of the present invention will be described with reference to FIGS. 4 to 6. In FIGS. 4 to 6, parts similar to those in the first embodiment are designated by the same reference numerals.

As shown in FIG. 4, this second embodiment device controls the temperature by turning on and off electricity to the heater 5, with the batteries 16a and 16b always connected in series when the heater 5 is in operation. Control is performed by a central control unit (hereinafter referred to as CPU) 38 which also serves as an operation control device and an energization control device. This CPU 38 includes a clogging sensor 24, a temperature sensor A14, and a temperature sensor B1.
Each detection signal from 5 is input, and the CPU 38 controls relay A19 and relay B based on these input signals.
20, the relay C21 is turned ON and OFF, and a bypass passage opening/closing signal 38a and an energization amount control signal 38b are output. A variable resistor 39 is inserted between the relay C21 and the heater 5, and the relay D39 controls the temperature of the heater 5 by turning on and off the current to the heater 5. At signal 38b
It is controlled ON and OFF.

The operation of the apparatus of the second embodiment configured as described above will be explained with reference to FIGS. 5 and 6. At step 40 in FIG. 5, the CPU 38 is initialized, and the process proceeds to step 41. In this step 41, the detection signal of the clogging sensor 24 is sent to the CPU.
38. Then, in step 42, the CPU 38 determines whether or not there is a clogging condition, and if the clogging condition occurs, the process proceeds to step 43, and if the clogging condition does not occur, the process returns to step 41. At step 43, the CPU 38 turns on relay C21 and proceeds to step 44. This step 44
Then CPU38 turns on relay A19 and relay B20.
Operate and connect batteries 16a and 16b in series.
A power supply voltage of 24V is applied to the heater 5. At this time, the relay D39 is set to ON operation.
Next, in step 45, the CPU 38 outputs the bypass passage opening/closing signal 38a to open the bypass passage 6, and the process proceeds to step 46. This step 46
Then, the detection signal from the temperature sensor B15 is input to the CPU 38, and the process proceeds to step 47. In this step 47, the CPU 38 determines whether the temperature T of the filter member 3 is equal to the heat resistance limit T ₀ or not, and if T=T ₀ . Proceed to. In step 49, the CPU 38 outputs the energization amount control signal 38b to the relay D39, and repeats energization and deactivation of the heater 5 to prevent the temperature T of the filter member 3 from exceeding the heat resistance limit _T0 .
is maintained at approximately T ₀ . Therefore, as shown in FIG. 6, the temperature of the filter member 3 rises rapidly in the initial stage of energization, and after the time it reaches T ₀ , the temperature T is maintained at approximately T ₀ so as not to exceed T ₀ . It turns out.

In step 48, the temperature sensor A is connected to the CPU 38.
14 detection signals are input, and the process proceeds to step 50. In step 50, the CPU 38 determines whether or not the clogging has been cleared. If the clogging has been cleared, the process proceeds to step 51, and if the clogging has not been cleared, the process returns to step 48. Then, in step 51, the CPU 38 sends relay A19, relay B20,
Turn off relay C21 and bypass passage 6
to close and return to the normal state.

The apparatus of the second embodiment described above can provide the following effects in addition to the effects obtained in the first embodiment. That is, the temperature T of the filter member 3 is T ₀
Since the temperature T is maintained at approximately T ₀ so as not to exceed T 0 after reaching T ₀ , the time required to burn and remove the particulate components can be further shortened.

Note that the present invention is not limited to the above-mentioned embodiments; for example, the clogging sensor 24 is not limited to determining the clogging state based on fuel consumption, but also uses distance traveled, engine operating time, and resistance value of the filter member. It can also be determined by detecting changes in engine back pressure, etc. Also, it is possible to determine whether the clogging has cleared or not.
Not limited to the detected temperature of temperature sensor A14, but also the heat resistance limit
The determination may be made based on the elapsed time after reaching T ₀ .

(Effect of the invention) As explained above, according to the invention, the operation control device controls the energization of the electric heating element that burns and removes the particulate components deposited on the filter member, and the operation control signal from the operation control device controls the energization of the electric heating element. The power supply voltage applied to the electric heating element is switched using the energization control device, which connects multiple power supplies in series and applies high voltage to the electric heating element. can perform rapid heating, and can apply normal voltage to other electrical components. Therefore, the present invention has great effects, such as being able to provide a diesel engine exhaust purification device that can reduce costs by using ordinary inexpensive electrical components.

[Brief explanation of the drawing]

Figures 1 to 3 are diagrams showing a first embodiment of the present invention, in which Figure 1 is a configuration diagram of the entire device, Figure 2 is a flowchart showing the operation of the device, and Figure 3 is a diagram showing temperature changes in the filter member. FIGS. 4 to 6 are diagrams showing the second embodiment of the present invention, and FIG. 4 is a configuration diagram,
FIG. 5 is a flowchart showing the operation of the device, and FIG. 6 is a characteristic diagram showing temperature changes in the filter member. 1...Exhaust passage, 3...Filter member, 5...
Heater (electric heating element), 12...Battery (power supply), 14...Temperature sensor A, 15...Temperature sensor B, 18...Electrical components, 19...Relay A, 20
... Relay B, 21 ... Relay C, 22 ... Operation control device, 23 ... Current supply control device, 24 ... Clogging sensor, 38 ... Central control unit, 39 ... Relay D.

Claims (1)

[Scope of utility model registration request] In an exhaust purification device for a diesel engine, a filter member for collecting particulate components in the exhaust gas is disposed in the exhaust passage of the engine, and an electric heating element is provided for burning and removing the particulate components collected by the filter member. A plurality of power supplies that can be selectively connected in series and parallel, an operation control device that outputs an energization signal to the electric heating element, and the plurality of power supplies are connected in series in accordance with the operation control signal of the operation control device. An exhaust gas purification device for a diesel engine, comprising: an energization control device that applies a power supply voltage to the electric heating element.